Characterization of Selected Drought Tolerance Rice Landraces: A Case in Kerala, India

*Kallingil Gopi Divya*

### **Abstract**

Rice is a staple food of more than half of the world's population. The successful cultivation of rice depends on a variety of climatic and soil conditions. There are lot of factors both biotic and abiotic, which affect the growth and yield of crops. Drought is one of the major abiotic stresses, which leads to drastic decline in the production of rice worldwide. In the present situation of severe climatic change, the scarcity of fresh water is diminishing at an alarming rate. Due to the sensitivity of rice crop and the enormous requirement for optimum yield, drought affects rice when compared to other food crops. Rice germplasm is endowed with scores of varieties and landraces that are reservoirs of genes which is capable of withstanding various abiotic stresses. These landraces can be used to tackle this abiotic stress and can fulfill the increasing demand of food.

**Keywords:** abiotic stress, drought, heat shock protein, landraces, proline

### **1. Introduction**

Human population is exploding day by day. By 2050, the world population is expected to reach the mark of nine billion, and to feed this enormous population, the food production needs to be increased by more than 50% [1]. Rice is agronomical and nutritional, one among the most important staple food satisfying the need of the calorie intake of approximately half of the population. To meet the future demand for food, anticipated from the projected world population increase, there is an urgent need to take all necessary steps to enhance the productivity of rice. The in-depth understanding of plant responses to abiotic stress needs to be achieved as the climate prediction models have demonstrated the increased rate of abiotic factors like drought, floods, salinity, and soaring temperature during the crop growing periods [2, 3]. Of the 470 Mts of worldwide production of rice, 90% is contributed from the Asian countries. The uneven pattern of rainfall has led to a marked decrease in the yield of upland cultivation. The reduction in the amount of fresh water causes serious stress to the crop production since nearly 5000 L/kg of water is required [4].

The staple food for almost two-third of the world's population, the rice is both nutritional and has medicinal values. Rice is a major source of carbohydrates, which are broken down into glucose upon digestion. Thus, it becomes a rich source of energy. The presence of resistant starch adds to its nutritive value. Since, rice lacks

sodium and cholesterol; it is greatly preferred as the staple food. Rice is gluten free and rich in vitamins like thiamine, niacin, iron, and riboflavin. The absence of preservatives and gluten makes it a preferable choice. In addition to the nutritional properties, there are some notable medicinal values for rice. The resistance starch encourages the growth of beneficial bacteria, which helps in keeping the bowel healthy. The high amount of insoluble fiber present in the whole grain is believed to be protective against many varieties of cancer. In addition to being the best food in dysenteric problems, it is also considered to be tonic, fattening, and aphrodisiac [5].

The IRRI 2010 have projected that rice requirement of 496 Mt in 2020 will increase up to 555 Mt in 2035 and will see an overall increase in the future. Global rice production in 2019 has been capped at 512 million tones [6]. Global rice consumption is recorded 494.5 million tons in 2019/20 [7]. Demand for rice is estimated to be 2000 million metric tons by 2030 [8], which has to be answered by immediate promising improvement in rice production in this era of drastic climate change and drought [9]. Of the total worldwide, rice production more than 50% of the area is rainfed and which accounts one quarter of total rice production [10]. World rice production is geographically concentrated in Western and Eastern Asia. Asia is the biggest rice producer, accounting for 90% of the world's production and consumption of rice. Asian farmers still account for 92% of the world's total rice production. Around 280 major rice varieties have been reported from India. There are thousands of strains of rice today, including those grown in wild and thosewhich are cultivated as crop.

Rice is grown under diverse conditions such as irrigated, rainfed lowland and flood prone ecosystems. It is the only crop that is grown in most fragile ecosystems and cultivated in all the agro-climatic zones below sea levels to the hilly areas. In rainfed ecosystems, drought is the major obstacle for rice production. As it is evident, drought seems to be the major obstacle in the rainfed ecosystem and causes severe loss in grain production. Pandey et al. have cited the example of various Indian states like Jharkhand, Orissa, and Chhattisgarh, which faces severe drought that had recorded a yield loss of 40% valued more than \$650 million [11]. Rice production in Kerala is tapering down, yielding just 6.3 lakh tone last year. The state produced only about 15% of its requirement in 2008 compared to 45% in 1956. The work undertaken by the Kerala Agricultural University focusing on the landraces pointed out the fact that Palakkad District contributes around one-third of the total state production [12].

### **2. Drought, the severe abiotic factor affecting rice production**

There are various factors affecting the growth development and yield of agriculture crops which can be classified as biotic and abiotic factors. According to the International Rice Research Institute (IRRI, 1998) projection, over the next two decades, India, Pakistan, the Philippines, and Vietnam will suffer, due to the sharp decrease in per capita water availability. Drought will be the most important abiotic factor which will lead to inter sectorial competition drastically affecting the need of agricultural water [13]. In Asia, approximately 34 million ha of shallow rain-fed lowland rice and 8 million ha of upland rice, totaling approximately one-third of the total Asian rice area are subjected to occasional or frequent drought stress [14]. Continuous drought and fresh-water scarcity has led to the increase of salinity level again giving rise to a new abiotic stress [15]. As paddy crop suffers from water stress at soil water contents even above field capacity drought affects the yield output. Farmers in most rainfed ecosystems, therefore, use the less risky traditional varieties and small amounts of fertilizers which often cause low production.

**29**

*Characterization of Selected Drought Tolerance Rice Landraces: A Case in Kerala, India*

Drought is the stress situation that lowers plant water potential and turgor pressure and alters the execution of normal physiological process. The challenge of drought is even greater for crops such as rice when compared with other crops such as maize and wheat due to its relatively higher water needs [16]. Around 4000 L of water is required for the production of 1 k of rice which is about double the amount needed for other crops [17]. Since rice cultivars have been grown since time memorable under flood irrigation conditions, rice is very sensitive to deficiency in soil water level as compared to many other field crops; the production systems of rice are more sensitive to drought and possess relatively weak resistances [18]. The water deficit arising with the drought can be classified as the – severe water deficit: available soil moisture 40–50%; moderate water deficit: available soil moisture 50–60%;

Sarvestani et al. has reported that as a result of reduced water level in the soil, the plant root stem uptakes reduced water leading to the yellowing of leaves due to the reduction in chlorophyll content [19]. The first noticeable response in respect to drought is the rolling of leaves which can help in reducing the internal water level [20]. Henderson et al. has also reported that leaf tip drying is also observed in drought affected plants [21]. The rice genotypes that possess high leaf rolling ability can produce high yield in comparison to other genotypes [22]. Bosco et al. have sustained the fact that the decrease in yield is a result of decrease in plant height, reduction in leaf area, and tillering ability [23]. Root characteristics, leaf temperature, flowering time, panicle exertion, maturity time, and spikelet fertility also affect the crop production [24]. An additional factor occurring due to drought stress resulting in yield reduction is the closure of stomata causing a sharp decrease in carbon dioxide intake directly reducing the photosynthesis rate [25]. The duration and severity of water scarcity determines the rate of reduction of life cycle and the extent of grain filling [26].

Erratic rainfall distribution is the most limiting factor of growing upland rice in India. Identification of relevant physiological stress tolerance mechanism and the genetic improvement of drought tolerance in crop plants need great attention [27]. Traditional varieties, wild relatives, native species, and modern cultivars together represent the wide genetic resources of the agriculture cops which form the basis of global food security. Genetic diversity provided farmers, plant physiologists, plant breeders, and biotechnologists with options to develop, through the natural selection, breeding and genetic manipulation, new crops, that are resistant to pests,

Landraces are generally called as the native varieties. They harbor a great genetic potential for crop improvement. As these are not subjected to subtle selection over many decades, they are endowed with tremendous genetic variability. This heterozygosity aids in the adaptation of landraces to wide agro-ecological niches and also possess unmatched qualitative traits and medicinal properties. This rich variability of complex quantitative traits still remains unexploited. Rice cultivation in the Kerala state of India situated in the southern Western Ghats dates back to 3000 B.C. [28]. There is immense genetic diversity in the germplasm of both wild and cultivated rice. The landraces present in the state are named according to morphological features, seed color, specific uses, growing conditions, etc. South Asian region is considered as the primary center [29], and Jeypore tract of Orissa is considered as the secondary center of rice and its wild relatives [30] in addition to the humid tropical coastal and mid-lands of Kerala with innumerable wild relative together

diseases, and adapted to changing environments (abiotic stress) [10].

*DOI: http://dx.doi.org/10.5772/intechopen.93396*

mild water deficit: available soil moisture 60–70%.

**3. Drought tolerance in rice landraces**

with more than 600 landraces [31].

### *Characterization of Selected Drought Tolerance Rice Landraces: A Case in Kerala, India DOI: http://dx.doi.org/10.5772/intechopen.93396*

Drought is the stress situation that lowers plant water potential and turgor pressure and alters the execution of normal physiological process. The challenge of drought is even greater for crops such as rice when compared with other crops such as maize and wheat due to its relatively higher water needs [16]. Around 4000 L of water is required for the production of 1 k of rice which is about double the amount needed for other crops [17]. Since rice cultivars have been grown since time memorable under flood irrigation conditions, rice is very sensitive to deficiency in soil water level as compared to many other field crops; the production systems of rice are more sensitive to drought and possess relatively weak resistances [18]. The water deficit arising with the drought can be classified as the – severe water deficit: available soil moisture 40–50%; moderate water deficit: available soil moisture 50–60%; mild water deficit: available soil moisture 60–70%.

Sarvestani et al. has reported that as a result of reduced water level in the soil, the plant root stem uptakes reduced water leading to the yellowing of leaves due to the reduction in chlorophyll content [19]. The first noticeable response in respect to drought is the rolling of leaves which can help in reducing the internal water level [20]. Henderson et al. has also reported that leaf tip drying is also observed in drought affected plants [21]. The rice genotypes that possess high leaf rolling ability can produce high yield in comparison to other genotypes [22]. Bosco et al. have sustained the fact that the decrease in yield is a result of decrease in plant height, reduction in leaf area, and tillering ability [23]. Root characteristics, leaf temperature, flowering time, panicle exertion, maturity time, and spikelet fertility also affect the crop production [24]. An additional factor occurring due to drought stress resulting in yield reduction is the closure of stomata causing a sharp decrease in carbon dioxide intake directly reducing the photosynthesis rate [25]. The duration and severity of water scarcity determines the rate of reduction of life cycle and the extent of grain filling [26].

### **3. Drought tolerance in rice landraces**

Erratic rainfall distribution is the most limiting factor of growing upland rice in India. Identification of relevant physiological stress tolerance mechanism and the genetic improvement of drought tolerance in crop plants need great attention [27]. Traditional varieties, wild relatives, native species, and modern cultivars together represent the wide genetic resources of the agriculture cops which form the basis of global food security. Genetic diversity provided farmers, plant physiologists, plant breeders, and biotechnologists with options to develop, through the natural selection, breeding and genetic manipulation, new crops, that are resistant to pests, diseases, and adapted to changing environments (abiotic stress) [10].

Landraces are generally called as the native varieties. They harbor a great genetic potential for crop improvement. As these are not subjected to subtle selection over many decades, they are endowed with tremendous genetic variability. This heterozygosity aids in the adaptation of landraces to wide agro-ecological niches and also possess unmatched qualitative traits and medicinal properties. This rich variability of complex quantitative traits still remains unexploited. Rice cultivation in the Kerala state of India situated in the southern Western Ghats dates back to 3000 B.C. [28]. There is immense genetic diversity in the germplasm of both wild and cultivated rice. The landraces present in the state are named according to morphological features, seed color, specific uses, growing conditions, etc. South Asian region is considered as the primary center [29], and Jeypore tract of Orissa is considered as the secondary center of rice and its wild relatives [30] in addition to the humid tropical coastal and mid-lands of Kerala with innumerable wild relative together with more than 600 landraces [31].

*Plant Stress Physiology*

which are cultivated as crop.

state production [12].

sodium and cholesterol; it is greatly preferred as the staple food. Rice is gluten free and rich in vitamins like thiamine, niacin, iron, and riboflavin. The absence of preservatives and gluten makes it a preferable choice. In addition to the nutritional properties, there are some notable medicinal values for rice. The resistance starch encourages the growth of beneficial bacteria, which helps in keeping the bowel healthy. The high amount of insoluble fiber present in the whole grain is believed to be protective against many varieties of cancer. In addition to being the best food in dysenteric problems, it is also considered to be tonic, fattening, and aphrodisiac [5]. The IRRI 2010 have projected that rice requirement of 496 Mt in 2020 will increase up to 555 Mt in 2035 and will see an overall increase in the future. Global rice production in 2019 has been capped at 512 million tones [6]. Global rice consumption is recorded 494.5 million tons in 2019/20 [7]. Demand for rice is estimated to be 2000 million metric tons by 2030 [8], which has to be answered by immediate promising improvement in rice production in this era of drastic climate change and drought [9]. Of the total worldwide, rice production more than 50% of the area is rainfed and which accounts one quarter of total rice production [10]. World rice production is geographically concentrated in Western and Eastern Asia. Asia is the biggest rice producer, accounting for 90% of the world's production and consumption of rice. Asian farmers still account for 92% of the world's total rice production. Around 280 major rice varieties have been reported from India. There are thousands of strains of rice today, including those grown in wild and those-

Rice is grown under diverse conditions such as irrigated, rainfed lowland and flood prone ecosystems. It is the only crop that is grown in most fragile ecosystems and cultivated in all the agro-climatic zones below sea levels to the hilly areas. In rainfed ecosystems, drought is the major obstacle for rice production. As it is evident, drought seems to be the major obstacle in the rainfed ecosystem and causes severe loss in grain production. Pandey et al. have cited the example of various Indian states like Jharkhand, Orissa, and Chhattisgarh, which faces severe drought that had recorded a yield loss of 40% valued more than \$650 million [11]. Rice production in Kerala is tapering down, yielding just 6.3 lakh tone last year. The state produced only about 15% of its requirement in 2008 compared to 45% in 1956. The work undertaken by the Kerala Agricultural University focusing on the landraces pointed out the fact that Palakkad District contributes around one-third of the total

**2. Drought, the severe abiotic factor affecting rice production**

and small amounts of fertilizers which often cause low production.

There are various factors affecting the growth development and yield of agriculture crops which can be classified as biotic and abiotic factors. According to the International Rice Research Institute (IRRI, 1998) projection, over the next two decades, India, Pakistan, the Philippines, and Vietnam will suffer, due to the sharp decrease in per capita water availability. Drought will be the most important abiotic factor which will lead to inter sectorial competition drastically affecting the need of agricultural water [13]. In Asia, approximately 34 million ha of shallow rain-fed lowland rice and 8 million ha of upland rice, totaling approximately one-third of the total Asian rice area are subjected to occasional or frequent drought stress [14]. Continuous drought and fresh-water scarcity has led to the increase of salinity level again giving rise to a new abiotic stress [15]. As paddy crop suffers from water stress at soil water contents even above field capacity drought affects the yield output. Farmers in most rainfed ecosystems, therefore, use the less risky traditional varieties

**28**

Landraces are also important genetic resources for resistant to pest and fungal diseases. "Velluthachira," "Bengle," and "Bhumanasam" are resistant to Rice gall midge; "Thadakan" is resistant to blast,"Buhjan" and "Laka" are resistant to brown plant hopper [32]. Owing to their specific domination in geographical niches, landraces have gene of resistance to abiotic stresses, which have not been widely used or incorporated into modern varieties. The South Indian Landraces "Norungan" and "Noortripathu" are now used as donors for drought tolerance [33].

The present scenario of predicted global food security needs to be tacked with the better understanding of natural selection, germplasm, responses of plant to abiotic stress, and improved yield under stress conditions. The identification of a traditional race, which can thrive well in stress prone area and genetic manipulation of plants that can maintain higher photosynthetic rates, better foliage growth and improved yield under stress conditions requires to be attended [34, 35]. There are a number of comprehensive reviews on drought response in plants [36–38]. Kamoshita et al. have reviewed the drought responses in upland rice [39]. Drought tolerance studies of the under-utilized heterozygous landraces which are bestowed with numerous beneficial properties are the need of the hour.

### **4. Screening of drought tolerance in rice**

One of the major phenomena encountered in almost all rice growing environments is drought. The methods to mitigate are to cultivate either the genotypes which have the capability to strive in the water scarcity or to develop new cultivars which can withstand the drought stress. The factors, which might have operated to create intra-varietal differences in the cultivated rice of Kerala can be attributed to the diverse climatic and ecological conditions which would have led to selection of varieties. The investigation was carried out to find out the best landrace with yield in both stressed and non-stressed environment which can be suggested as the best cultivar for upland cultivation. The recent approaches by functional genomics and genomics assisted breeding of abiotic stress tolerance are helpful in generating valuable information for engineering stress tolerant plants for their use in sustainable agriculture.

Exploration and collection of different accessions of landraces from different districts of Kerala were carried out. After primary screening, the following germplasm were selected to study the effect of drought and the ability of landraces to withstand it (**Tables 1** and **2**).

The seeds of selected landraces varieties were kept for germination. The approximate period for germination was recorded to be 7 days. After all the seeds were germinated, they were transferred to drought condition by withholding the water supply. The withholding resulted in the appearance of wilting signs. These seedlings were screened for their regaining capacities after re-watering. After completion of 7 days of germination, the seedlings were transferred to drought by withholding the input of water. Neither of them could survive 4 days in drought and they wilted and died. In the second phase, drought period was reduced to 3 days. After 72 hours of drought, the seedlings did show signs of wilting but once re-watered, they started to regain. The regaining capacity of the landraces showed district variation. After normal growth for 7 days the seedlings were transferred to drought condition. The areas of the leaves were recorded prior to their transfer into drought with the help of a graph paper and recorded as L1. After 3 days of drought, the leaves showed signs of wilting and started to roll. At that time, the leaf area was again calculated with the help of a graph paper and recorded, L2. Induction of heat shock proteins was done and quantified together with the total carbohydrates and proline. The healthy grains of the selected landraces along with check varieties were

**31**

**Table 1.** *Landraces selected.*

**Table 2.**

*Plumule and radicle length (cm).*

**4.1 Screening of root architecture**

*Characterization of Selected Drought Tolerance Rice Landraces: A Case in Kerala, India*

germinated under controlled condition by soaking in double distilled water 72 h, after germination and 50 seeds were exposed to a temperature of 42°C at uniform time intervals. The amount of protein accumulated was correlated with the level of drought tolerance of different landraces and the control and was estimated by the method of Lowry et al. [40]. Accumulation of proline is seen under stress conditions which is used as an energy source for survival and growth [41]. Proline is an osmoregulatory molecule which allows the cell to balance the osmotic strength of its cytoplasm with that of its surroundings to prevent a net loss of water. In addition to functioning as osmotic balancing agents, proline interacts with crucial macromolecules of the cell to maintain their biological activity during stress. It has been suggested that proline may also function as a sink of energy and reducing power, hydroxyl radical scavenger, a compatible solute that protects enzymes and also as a means of reducing acidity. The proline content of the drought treated samples and

**SN Landraces Plumule Radicle** Navara punja 9.425 11.27 Navara 9.275 11.9 Orkazhama 9.675 15.6 Vadakan 9.65 10.02 Vellaryan 9.7 10.85 Malakaran 10.975 15.02 Mundakan 9.75 14.27 Kuthiru 9.77 12.27 Kazhama 8.82 13.27

control seeds were analyzed according to the procedure of Bates et al. [42].

The root and shoot lengths of all the accessions studied before and after subjection to drought were recorded. From the data obtained its seen that with the induction of drought, there is a remarkable increase in the length of radicle, and

*DOI: http://dx.doi.org/10.5772/intechopen.93396*

**SN Name of landraces** 1. Navara punja 2. Navara 3. Oarkazhama 4. Vadakan 5. Vellaryan 6. Malakkaran 7. Mundakan 8. Kuthiru 9. Kazhama

*Characterization of Selected Drought Tolerance Rice Landraces: A Case in Kerala, India DOI: http://dx.doi.org/10.5772/intechopen.93396*


### **Table 1.**

*Plant Stress Physiology*

Landraces are also important genetic resources for resistant to pest and fungal diseases. "Velluthachira," "Bengle," and "Bhumanasam" are resistant to Rice gall midge; "Thadakan" is resistant to blast,"Buhjan" and "Laka" are resistant to brown plant hopper [32]. Owing to their specific domination in geographical niches, landraces have gene of resistance to abiotic stresses, which have not been widely used or incorporated into modern varieties. The South Indian Landraces "Norungan" and

The present scenario of predicted global food security needs to be tacked with the better understanding of natural selection, germplasm, responses of plant to abiotic stress, and improved yield under stress conditions. The identification of a traditional race, which can thrive well in stress prone area and genetic manipulation of plants that can maintain higher photosynthetic rates, better foliage growth and improved yield under stress conditions requires to be attended [34, 35]. There are a number of comprehensive reviews on drought response in plants [36–38]. Kamoshita et al. have reviewed the drought responses in upland rice [39]. Drought tolerance studies of the under-utilized heterozygous landraces which are bestowed

One of the major phenomena encountered in almost all rice growing environments is drought. The methods to mitigate are to cultivate either the genotypes which have the capability to strive in the water scarcity or to develop new cultivars which can withstand the drought stress. The factors, which might have operated to create intra-varietal differences in the cultivated rice of Kerala can be attributed to the diverse climatic and ecological conditions which would have led to selection of varieties. The investigation was carried out to find out the best landrace with yield in both stressed and non-stressed environment which can be suggested as the best cultivar for upland cultivation. The recent approaches by functional genomics and genomics assisted breeding of abiotic stress tolerance are helpful in generating valuable information for engineering stress tolerant plants for their use in sustainable agriculture. Exploration and collection of different accessions of landraces from different districts of Kerala were carried out. After primary screening, the following germplasm were selected to study the effect of drought and the ability of landraces to

The seeds of selected landraces varieties were kept for germination. The approximate period for germination was recorded to be 7 days. After all the seeds were germinated, they were transferred to drought condition by withholding the water supply. The withholding resulted in the appearance of wilting signs. These seedlings were screened for their regaining capacities after re-watering. After completion of 7 days of germination, the seedlings were transferred to drought by withholding the input of water. Neither of them could survive 4 days in drought and they wilted and died. In the second phase, drought period was reduced to 3 days. After 72 hours of drought, the seedlings did show signs of wilting but once re-watered, they started to regain. The regaining capacity of the landraces showed district variation. After normal growth for 7 days the seedlings were transferred to drought condition. The areas of the leaves were recorded prior to their transfer into drought with the help of a graph paper and recorded as L1. After 3 days of drought, the leaves showed signs of wilting and started to roll. At that time, the leaf area was again calculated with the help of a graph paper and recorded, L2. Induction of heat shock proteins was done and quantified together with the total carbohydrates and proline. The healthy grains of the selected landraces along with check varieties were

"Noortripathu" are now used as donors for drought tolerance [33].

with numerous beneficial properties are the need of the hour.

**4. Screening of drought tolerance in rice**

withstand it (**Tables 1** and **2**).

**30**

*Landraces selected.*


### **Table 2.**

*Plumule and radicle length (cm).*

germinated under controlled condition by soaking in double distilled water 72 h, after germination and 50 seeds were exposed to a temperature of 42°C at uniform time intervals. The amount of protein accumulated was correlated with the level of drought tolerance of different landraces and the control and was estimated by the method of Lowry et al. [40]. Accumulation of proline is seen under stress conditions which is used as an energy source for survival and growth [41]. Proline is an osmoregulatory molecule which allows the cell to balance the osmotic strength of its cytoplasm with that of its surroundings to prevent a net loss of water. In addition to functioning as osmotic balancing agents, proline interacts with crucial macromolecules of the cell to maintain their biological activity during stress. It has been suggested that proline may also function as a sink of energy and reducing power, hydroxyl radical scavenger, a compatible solute that protects enzymes and also as a means of reducing acidity. The proline content of the drought treated samples and control seeds were analyzed according to the procedure of Bates et al. [42].

### **4.1 Screening of root architecture**

The root and shoot lengths of all the accessions studied before and after subjection to drought were recorded. From the data obtained its seen that with the induction of drought, there is a remarkable increase in the length of radicle, and


**Table 3.**

*Root performance under drought (cm).*

numerous root hairs make their appearance. This might be for the increasing of the absorption area. Kuthiru has the longest shoot while Kazhama has the shortest. With respect to roots, Oarkazhama has the longest roots followed by Malakkaran and Kuthiru. Vaddakan has the smallest, and deteriorated radicle was shown by Navara. After a period of 3 days, the seedlings were watered and their regaining capacity and performance is depicted in **Table 3**. Root system architecture is one of the most important contributors to drought resistance in crops [26]. A well-developed root system is a key to ensuring stable and high yields under drought [43], and the greater root length in deeper soil layers has been shown to increase yield by allowing more water extraction [44]. Supporting to this, the current investigation also revealed the formation of dense root system on subjection to drought. Since rice is characterized by a shallower and more fibrous root system, it has limited water extraction below 60 cm [45]. The lateral root of rice showed greater development under drought [46], which would accelerate drought stress in 20 cm deep soil adverse to rice production.

Since the landraces Njavara, Njavara punja Vadakan and Vellaryan did not show any marked drought tolerance and could not withstand the initial drought stress; they were not subjected to further studies.

### **4.2 Estimation of leaf area**

The leaf area index that reduces due to the subjective stress was compared with normal ones grown under optimum conditions. All the accessions showed decrease in leaf area, and the maximum reduction was shown by the accession, "Malakkaran" and minimum by "Kazhama." There was a clear indication that the accessions tend to reduce the leaf area during drought condition (**Table 4**).

### **4.3 Estimation of heat shock proteins (HSPS)**

The concentration of heat shock accumulated is then found out by the method of Lowry et al. The amount of heat shock protein accumulated by induction together with the amount induced by drought is summarized in **Table 5**.


**33**

regulated.

**Table 5.**

*Heat shock proteins in rice.*

to drought stress by heat shock [49].

results obtained are summarized below (**Table 6**).

improvement in drought tolerance in plants [50, 52].

**4.4 Estimation of proline**

*Characterization of Selected Drought Tolerance Rice Landraces: A Case in Kerala, India*

**SN Landraces Raw Control Drought induced** Orkazhama 139.41 169.41 181.17 Malakaran 116.47 110.0 199.41 Mundakan 104.7 173.5 194.70 Kuthiru 113.52 169.38 193.53 Kazhama 124.7 165.49 181.76

The concentration of the heat shock protein increases when the seeds are subjected to drought. And the amount is the lowest in Oarkazhama and highest in Malakkaran in the case of raw seeds. Once drought is induced, it is seen that there is an increase in the Hsp's. These may help them to tolerate the advent of water stress. Plant growth regulators modulate plant response to unfavorable environment. Heat shock proteins (HSPs) are expressed at a very high rate when the cells are exposed to increased temperature, and its activity and expressions are co

The increasing global temperature and the reduction in the available water content for the crops subject them to survive in elevated temperatures. Park et al. reported that the hsp 90 genes and hsp 90 proteins are found in rice [47]. They are induced by elevated temperature stress but their levels are reasonably large even at low temperatures. These hsps provide the temperature affected rice to combat the degradative effect of heat. Yeh et al. reported that a recombinant rice of 16.9 kda heat shock protein can provide thermo protection in vitro [48]. Hsp 100 family has been directly implicated in the induction of thermo tolerance in microbial and animal cells. Jie Zou showed that rice small Hsp gene, shsps 17.7, the product which acts as molecular chaperons aid to determine the mechanism of acquisition of tolerance

Following the procedure of Bates et al., the concentration of the basic amino acid proline, which has to play a great role in stress condition was determined. The

during water stress. It also enables stomata to remain partially open and CO2 assimilation to continue at water potentials that would be otherwise inhibitory for CO2 assimilation [51]. Proline can scavenge free radicals and reduce damage due to free radicles during drought stress. Growing body of evidence indicated that proline content increases during drought stress and proline accumulation is associated with

The amount of proline in raw seeds is very less. The value increases only negligibly once the seedlings germinated. But the induction of drought stress remarkably contributes toward the increase of proline content which helps the seedlings to survive in stress period. The landraces Malakkaran showed the highest amount of proline in both raw seeds and also after introduction of drought. While Kuthiru and Kazhama were the landraces possessing the least amount. The landraces which had thrived well in the drought condition showed increase in the proline content. Proline, a compatible solute and an amino acid, is involved in osmotic adjustment (OA) and protection of cells during dehydration [50]. Cell turgor is maintained due to osmotic adjustments, which allows cell enlargement and plant growth

*DOI: http://dx.doi.org/10.5772/intechopen.93396*

**Table 4.** *Leaf area index of drought induction (in cm).* *Characterization of Selected Drought Tolerance Rice Landraces: A Case in Kerala, India DOI: http://dx.doi.org/10.5772/intechopen.93396*


**Table 5.**

*Plant Stress Physiology*

**Table 3.**

*Root performance under drought (cm).*

they were not subjected to further studies.

**4.3 Estimation of heat shock proteins (HSPS)**

**4.2 Estimation of leaf area**

numerous root hairs make their appearance. This might be for the increasing of the absorption area. Kuthiru has the longest shoot while Kazhama has the shortest. With respect to roots, Oarkazhama has the longest roots followed by Malakkaran and Kuthiru. Vaddakan has the smallest, and deteriorated radicle was shown by Navara. After a period of 3 days, the seedlings were watered and their regaining capacity and performance is depicted in **Table 3**. Root system architecture is one of the most important contributors to drought resistance in crops [26]. A well-developed root system is a key to ensuring stable and high yields under drought [43], and the greater root length in deeper soil layers has been shown to increase yield by allowing more water extraction [44]. Supporting to this, the current investigation also revealed the formation of dense root system on subjection to drought. Since rice is characterized by a shallower and more fibrous root system, it has limited water extraction below 60 cm [45]. The lateral root of rice showed greater development under drought [46], which would accelerate drought stress in 20 cm deep soil adverse to rice production. Since the landraces Njavara, Njavara punja Vadakan and Vellaryan did not show any marked drought tolerance and could not withstand the initial drought stress;

**SN Landraces Plumule length Radicle length** 1 Orkazhama >10 Replaced by fibrous roots

4 Kazhama >11 Replaced by fibrous roots 5 Kuthiru >14 Replaced by fibrous roots

2 Malakaran >9 >7.8. 3 Mundakan >8.7 >7.5

The leaf area index that reduces due to the subjective stress was compared with normal ones grown under optimum conditions. All the accessions showed decrease in leaf area, and the maximum reduction was shown by the accession, "Malakkaran" and minimum by "Kazhama." There was a clear indication that the accessions tend to reduce the leaf area during drought condition (**Table 4**).

The concentration of heat shock accumulated is then found out by the method

**SN Landraces Normal Drought induced % Reduction** Oarkazhama 17.0 12.5 26 Malakaran 18.9 11.7 38 Mundakan 19.4 12.3 36 Kuthiru 16.9 11.0 34 Kazhama 20.7 17.9 14

of Lowry et al. The amount of heat shock protein accumulated by induction together with the amount induced by drought is summarized in **Table 5**.

**32**

**Table 4.**

*Leaf area index of drought induction (in cm).*

*Heat shock proteins in rice.*

The concentration of the heat shock protein increases when the seeds are subjected to drought. And the amount is the lowest in Oarkazhama and highest in Malakkaran in the case of raw seeds. Once drought is induced, it is seen that there is an increase in the Hsp's. These may help them to tolerate the advent of water stress. Plant growth regulators modulate plant response to unfavorable environment. Heat shock proteins (HSPs) are expressed at a very high rate when the cells are exposed to increased temperature, and its activity and expressions are co regulated.

The increasing global temperature and the reduction in the available water content for the crops subject them to survive in elevated temperatures. Park et al. reported that the hsp 90 genes and hsp 90 proteins are found in rice [47]. They are induced by elevated temperature stress but their levels are reasonably large even at low temperatures. These hsps provide the temperature affected rice to combat the degradative effect of heat. Yeh et al. reported that a recombinant rice of 16.9 kda heat shock protein can provide thermo protection in vitro [48]. Hsp 100 family has been directly implicated in the induction of thermo tolerance in microbial and animal cells. Jie Zou showed that rice small Hsp gene, shsps 17.7, the product which acts as molecular chaperons aid to determine the mechanism of acquisition of tolerance to drought stress by heat shock [49].

### **4.4 Estimation of proline**

Following the procedure of Bates et al., the concentration of the basic amino acid proline, which has to play a great role in stress condition was determined. The results obtained are summarized below (**Table 6**).

The amount of proline in raw seeds is very less. The value increases only negligibly once the seedlings germinated. But the induction of drought stress remarkably contributes toward the increase of proline content which helps the seedlings to survive in stress period. The landraces Malakkaran showed the highest amount of proline in both raw seeds and also after introduction of drought. While Kuthiru and Kazhama were the landraces possessing the least amount. The landraces which had thrived well in the drought condition showed increase in the proline content.

Proline, a compatible solute and an amino acid, is involved in osmotic adjustment (OA) and protection of cells during dehydration [50]. Cell turgor is maintained due to osmotic adjustments, which allows cell enlargement and plant growth during water stress. It also enables stomata to remain partially open and CO2 assimilation to continue at water potentials that would be otherwise inhibitory for CO2 assimilation [51]. Proline can scavenge free radicals and reduce damage due to free radicles during drought stress. Growing body of evidence indicated that proline content increases during drought stress and proline accumulation is associated with improvement in drought tolerance in plants [50, 52].


**Table 6.**

*Proline content in rice.*

From the physiological and biochemical results, it is quite clear that the increased higher accumulation of the stress amino acid proline renders Malakkaran followed by Kuthiru the ability to withstand the drought conditions. These two landraces showed more adaptability to drought stress. And if the particular seeds can withstand the severe drought condition, then they can be successfully used for cultivation purposes. From the study undertaken, it is obvious that the two landraces, Malakkaran and Kuthiru can be used for even the upland cultivation even in severe drought periods.

Drought contributes directly to an increase in the incidence and severity of poverty. It is therefore critical that we establish effective strategies to mitigate the effects of drought in order to ensure agricultural productivity and environmental sustainability. The use of landraces which can thrive well in the drastic water scarcity can result in optimum yield which would help in fulfilling the adequate food availability of the increasing human population. As the pressure on land and its resources are increasing with the population growth, there is a noticeable decrease in the low land areas suitable for rice cultivation. The practice of cultivating cultivars which have promising characteristics to tolerate the abiotic stress is the need of the hour.

### **5. Conclusion**

The increased frequency of drought in arable region threatens rice production and demands the development of rice genotype capable of producing more from diminishing water resources. The development of rice cultivars with improved drought tolerance is thus an important element in reducing risk, increasing productivity, and alleviating poverty in communities dependent on rain-fed production. These landraces with the potential to withstand drought condition should be cultivated to harness their potential. The repository of hidden treasures of tolerant genes in the underutilized landraces present in the state of Kerala with maximum water use efficiency mitigate can prove to be the best in alleviating the drought stress.

### **Acknowledgements**

I deeply acknowledge the support and suggestions provided by Dr. Maya C Nair, Head and Associate Professor of Botany, Government Victoria College, Palakkad, Kerala.

**35**

**Author details**

Kallingil Gopi Divya

*Characterization of Selected Drought Tolerance Rice Landraces: A Case in Kerala, India*

Department of Pharmacognosy, Siddha Central Research Institute, Chennai, India

© 2020 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

\*Address all correspondence to: minnu.kg@gmail.com

provided the original work is properly cited.

*DOI: http://dx.doi.org/10.5772/intechopen.93396*

### **Conflict of interest**

Nil

*Characterization of Selected Drought Tolerance Rice Landraces: A Case in Kerala, India DOI: http://dx.doi.org/10.5772/intechopen.93396*

### **Author details**

*Plant Stress Physiology*

**Table 6.**

*Proline content in rice.*

**5. Conclusion**

**Acknowledgements**

**Conflict of interest**

From the physiological and biochemical results, it is quite clear that the increased higher accumulation of the stress amino acid proline renders Malakkaran followed by Kuthiru the ability to withstand the drought conditions. These two landraces showed more adaptability to drought stress. And if the particular seeds can withstand the severe drought condition, then they can be successfully used for cultivation purposes. From the study undertaken, it is obvious that the two landraces, Malakkaran and Kuthiru can be used for even the upland cultivation even in severe drought periods. Drought contributes directly to an increase in the incidence and severity of poverty. It is therefore critical that we establish effective strategies to mitigate the effects of drought in order to ensure agricultural productivity and environmental sustainability. The use of landraces which can thrive well in the drastic water scarcity can result in optimum yield which would help in fulfilling the adequate food availability of the increasing human population. As the pressure on land and its resources are increasing with the population growth, there is a noticeable decrease in the low land areas suitable for rice cultivation. The practice of cultivating cultivars which have promising characteristics to tolerate the abiotic stress is the need of the hour.

**SN Landraces Raw Control Drought induced** Orkazhama 0.23 0.56 0.86 Malakaran 0.28 0.65 0.92 Mundakan 0.13 0.49 0.81 Kuthiru 0.14 0.38 0.83 Kazhama 0.07 0.41 0.80

The increased frequency of drought in arable region threatens rice production and demands the development of rice genotype capable of producing more from diminishing water resources. The development of rice cultivars with improved drought tolerance is thus an important element in reducing risk, increasing productivity, and alleviating poverty in communities dependent on rain-fed production. These landraces with the potential to withstand drought condition should be cultivated to harness their potential. The repository of hidden treasures of tolerant genes in the underutilized landraces present in the state of Kerala with maximum water use efficiency mitigate can prove to be the best in alleviating the drought stress.

I deeply acknowledge the support and suggestions provided by Dr. Maya C Nair, Head and Associate Professor of Botany, Government Victoria College, Palakkad,

**34**

Kerala.

Nil

Kallingil Gopi Divya Department of Pharmacognosy, Siddha Central Research Institute, Chennai, India

\*Address all correspondence to: minnu.kg@gmail.com

© 2020 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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[21] Henderson SA, Kamboonruang V, Copper M. Evaluation of a glasshouse screening method to select for drought resistance in rainfed lowland rice. In: International Rice Research Conference on Fragile Lives in Fragile Ecosystems, Los Banos, Laguna (Philippines), 13-17 Feb 1995. IRRI; 1995

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[23] Bosco R, Lorieux M, Futakuchi K, Manney B, Baimey H, Ndjiondjop MN. Agro-morphological characterization of a population of introgression lines derived from crosses between IR 64 (*O. sativa indica*) and TOG 5681 (*O. glaberrima*) for drought tolerance. Plant Science. 2011;**183**:65-76

[24] Ndjiondjop MN, Cisse F, Girma G, Sow M, Bocco R, Djedatin G, et al. Morpho-agronomic and molecular characterization of Oryza glaberrima germplasm from Mali. African Journal of Biotechnology. 2010;**9**(44):7409-7417 [25] Flexas J, Bota J, Cifre J, Mariano Escalona J, Galmés J, Gulías J, et al. Understanding down-regulation of photosynthesis under water stress: Future prospects and searching for physiological tools for irrigation management. The Annals of Applied Biology. 2004;**144**(3):273-283

[26] Farooq M, Hussain M, Siddique KHM. Drought stress in wheat during flowering and grain-filling periods. Critical Reviews in Plant Sciences. 2014;**33**:331-349. DOI: 10.1080/07352689.2014.875291

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[30] Sampath S. Wild rices of Orissa and their relationship to the cultivated varieties. Rice News Teller. 1958;**6**(3):17-20

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**36**

2007;**92**:187-237

*Plant Stress Physiology*

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[11] Pandey S, Bhandari HS, Hardy B. Economic Costs of Drought and Rice Farmers' Coping Mechanisms: A Cross-Country Comparative Analysis. Los Banos, Philipines: International Rice

[12] Kumari SL. Status Paper on Rice in

[14] Huke RE, Huke EH. Rice: Then and Now. Los Banos, Philipines: International

[13] IRRI. Sustaining Food Security Beyond the Year 2020. LosBaños, Philippines: A Global Partnership for Rice Research, IRRI Rolling Medium

Term Plan 1991-2000; 1998

Rice Research Institute; 1990

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in Agriculture. 1985;**1**:665-699

[16] Todaka D, Shinozaki K, Yamaguchi-Shinozaki K. Recent advances in the dissection of droughtstress regulatory networks and strategies for development of droughttolerant transgenic rice plants. Frontiers

in Plant Science. 2015;**6**:84

2005;**74**(2):87-105

Thailand; 2004

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[18] O'Toole JC. Rice and water: The final frontier. In: The First International Conference on Rice for the Future Rockefeller Foundation. Bangkok,

Research Institute; 2007. p. 203

Kerala; 2012

FAO, Rome; 2002. p. 253

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*Plant Stress Physiology*

2007;**48**(4):337-345

markers. Journal of Applied Genetics.

for water-stress studies. Plant and Soil.

[43] Dodd IC, Whalley WR, Ober ES, Parry MA. Genetic and management approaches to boost UK wheat yields by ameliorating water deficits. Journal of Experimental Botany. 2011;**62**:5241-

5248. DOI: 10.1093/jxb/err242

[44] Manschadi AM, Christopher J, Devoil P, Hammer GL. The role of root architectural traits in adaptation of wheat to water-limited environments. Functional Plant Biology. 2006;**33**: 823-837. DOI: 10.1071/FP06055

[45] Fukai S, Inthapan P. Growth and yield of rice cultivars under sprinkler irrigation in South-Eastern Queensland. 1. Effects of sowing time. Aust. Journal of Experimental Agriculture. 1988;**28**:237-242. DOI:

[46] Kameoka E, Suralta RR, Mitsuya S, Yamauchi A. Developmental plasticity of rice root system grown under mild drought stress condition with shallow soil depth; comparison between nodal and lateral roots. Plant Production Science. 2016;**19**:411-419. DOI: 10.1080/1343943X.2015.1128094

[47] Park M, Kang CY, Krishna P. *Brassica napus* Hsp90 can autophosphorylate and phosphorylate other protein substrates. Molecular and Cellular Biochemistry.

[48] Yeh CH, Yeh KW, Wu SH, Chang PF, Chen YM, Lin CY. A recombinant rice 16.9-kDa heat shock protein can provide thermoprotection in vitro. Plant & Cell Physiology. 1995;**36**(7):1341-1348

[49] Zou J, Liu A, Chen X, Zhou X, Gao G, Wang W, et al. Expression analysis of nine rice heat shock protein genes under abiotic stresses and ABA treatment. Journal of Plant Physiology.

2009;**166**(8):851-861

10.1071/EA9880237

1998;**185**:33-38

1973;**39**(1):205-207

Mullineaux PM, Davies WJ. Improving

Philosophical Transactions of the Royal Society of London. Series B, Biological

[36] Ingram J, Bartels D. The molecular basis of dehydration tolerance in plants. Annual Review of Plant

Physiology and Plant Molecular Biology.

[37] Holmberg N, Bülow L. Improving stresstoleranceinplantsbygene transfer. Trends in Plant Science. 1998;**3**:61-66

[38] Farooq M, Basra SMA, Khalid M, Tabassum R, Mehmood T. Nutrient homeostasis, reserves metabolism and seedling vigor as affected by seed priming in coarse rice. Canadian Journal

Boopathi NM, Fukai S. Phenotypic and genotypic analysis of drought-resistance traits for development of rice cultivars adapted to rainfed environments. Field

[40] Lowry OH, Rosebrough NJ, Farr AL, Randall RJ. Protein measurement with the Folin phenol reagent. The Journal of Biological Chemistry.

[41] Kaur-Sawhney R, Tiburcio AF, Altabella T, Galston AW. Polyamines in plants: An overview. Cellular and Molecular Biology. 2003;**2**:1-2

[42] Bates LS, Waldren RP, Teare ID. Rapid determination of free proline

of Botany. 2006a;**84**:1196-1202

Crops Research. 2008;**109**:1-23

1951;**193**(1):265-275

[39] Kamoshita A, Babu RC,

[34] Condon AG, Richards RA, Rebetzke GJ, Farquhar GD. Breeding for high water-use efficiency. Journal of Experimental Botany.

2004;**55**(407):2447-2460

[35] Morison JIL, Baker NR,

water use in crop production.

Sciences. 2008;**363**:639-658

1996;**47**:377-403

**38**

[51] Alves AAG, Setter TL. Abscisic acid accumulation and osmotic adjustment in cassava under water deficit. Environmental and Experimental Botany. 2004;**51**:259-279

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**Chapter 3**

**Abstract**

antioxidants

**41**

**1. Introduction**

The Response of Maize Physiology

*Shazia Iqbal, Sajid Hussain, Muhammad Abdul Qayyaum,*

Maize is a cross-pollinated, polymorphic plant in nature. It is commonly a moderately salt-sensitive crop. Salinity stress is the main abiotic factor that arrests the physiological characteristics and plant growth of a maize plant. It causes the osmotic effect, associated with an increase in phytotoxic ions, oxidative stress by increased reactive oxygen species (ROS) production, and ionic effect in the cytosol. These salinity effects hinder the maize plant's physiological processes such as respiration, photosynthesis, transpiration, stomatal functioning, hormone regulation, and functioning, seed germination, and dormancy and water relation with plants and ultimately reduce the plant growth and yield. However, the physiology of maize subjected to salinity shows various responses that depend on the genetic responses and growth stages. Maize plant undergoes many physiological changes and adapts some mechanism internally to cope with salinity stress. Numerous mitigating strategies such as application of chemicals, application of plant growthpromoting rhizobacteria (PGPR), application of hormones, and use of genetic and molecular techniques are used to handle salinity. This chapter will cover the effect of salinity on maize growth, its physiology, and physiological adaptations of maize

**Keywords:** *Zea mays* L., salinity, physiology, genetic and molecular techniques,

Soils with an excessive amount of soluble salts or exchangeable sodium in the root zone are termed salt-affected soils. Owing to limited rainfall and high evapotranspiration demand, coupled with poor soil and water management practices, salt stress has become a serious threat to crop production in arid and semi-arid regions of the world [1, 2]. Although the general perception is that salinization only occurs in arid and semi-arid regions, no climatic zone is free from this problem [3]. More than 800 million hectares of land worldwide is affected by either salinity

Maize (*Zea mays* L.) is the third most important cereal crop after rice and wheat and is grown under a wide spectrum of soil and climatic conditions. It is an important C4 plant from the *Poaceae* family and is moderately sensitive to salt stress;

(397 million hectares) or sodicity (434 million hectares) [4–6].

under Salinity Stress and Its

Coping Strategies

*Muhammad Ashraf and Saifullah*

plants with management strategies.

### **Chapter 3**
