**1. Introduction**

The world population is increasing and is projected to rise by more than 1 billion by 2030 and over 2.4 billion by 2050 [1]. Therefore, to feed the increasing population, agricultural food production must be increased by 70% by 2050 [2]. In the event of growing concerns of uncertainties in climatic conditions, the abiotic stresses have become the major threat to agriculture production worldwide. Drought is one of the most important abiotic stresses which affect crop growth and yield. In Bangladesh drought is a major threat to agricultural production. As maize is usually a winter condition and due to low rainfall, the growth of maize and yield of maize are severely affected by drought stress [3]. Under drought stress, plant photosynthesis can significantly decrease, consequently reducing the amount and energy of metabolites [4] required for the proper development of both the aboveand belowground biomass [5]. In severe water shortage conditions, the roots will shrink and in the leaves induced deposition. In drought conditions, reduced water potential and increased cell content of ABA regulate the metabolism of cells.

Increase in substances such as proline can be one of the major molecular responses to drought stress [6]. Drought stress-induced free radicals cause lipid peroxidation and membrane deterioration in plants [7].

Maize is the third most important cereal crops in Bangladesh, after rice and wheat. It can be cultivated year round. The crop is high yielding and rich in nutrient and has diversified uses. The demand of maize in Bangladesh is primarily from the commercial feed processing industry. This industry is the driving force of maize sector, using 80% of its aggregate maize production (excluding imports), and statistically, the poultry sector (a significant representative of feed industry) is growing at an average rate of 23% per year [8].Therefore, production of maize needs to be increased. However maize production is severely affected by drought stress. Water absorption, imbibition, and metabolic enzymatic activation are hindered under limited water availability which reduces the maize grain germination. Root and shoot elongations are parameters of seedling growth, and these are subjected to reduction by drought stress. At seedling stage in maize, reduction in shoot elongation is more than root elongation under drought stress [9]. Application of biochar is such technology which can mitigate adverse effects of drought stress on maize.

154.3, and 145.0 cm, respectively, when biochar was applied at 20 t/ha, and lowest plant heights of maize were 150.6, 139.0, and 134.3 cm, respectively, when no biochar was applied. So it is clear that plant height is affected by drought conditions and application of rice husk biochar mitigated the effect of drought condition by increasing plant height. Similar result was reported in maize by [17]. Biochar promoted plant height of maize under drought conditions [18]. By affecting cell turgidity, drought impaired plant height [19]. Application of biochar can increase soil water-holding capacity which increased tissue water status and ultimately increased

**6th leaf stage (cm) 10th leaf stage (cm) 14th leaf stage (cm)**

**40% of FC**

**Control 60% of FC**

**40% of FC**

**Control 60% of FC**

 39.4de 39.1e 38.7f 90.4b 89.5b 80.2b 150.60d 139.0f 134.3f 42.2a–e 40.9b-e 40.2 c–e 91.2ab 90.4b 90.3b 156.6c 145.3e 136.3f 42.8a–c 41.9a–e 41.2b–e 93.9ab 91.4ab 90.7b 164.0b 151.3d 138.3f 44.8a 43.8ab 42.0a–e 95.4a 93.0ab 91.2ab 169.3a 154.3cd 145.0e

CV (%) 4.2 3.1 2.0

*Effect of rice husk biochar on plant height of maize at vegetative stages under drought conditions.*

**2.2 Effect of rice husk biochar on plant height of maize at reproductive stages**

Plant height differences of maize at reproductive stages indicated that plant height varied due to different doses of biochar under drought conditions (**Table 2**). At tasseling stage, under control condition (80% of FC), 60% of field capacity, and 40% of field capacity, highest plant heights of maize were 190.0, 184.3, and 165.6 cm, respectively, when biochar was applied at 20 t/ha, and lowest plant heights of maize were 164.0, 161.6, and 136.6 cm, respectively, when no biochar was applied. At cob initiation stage, under control condition (80% of FC), 60% of field capacity, and 40% of field capacity, highest plant heights of maize were 195.6, 190.3, and 169.0 cm, respectively, when biochar was applied at 20 t/ha, and lowest plant heights of maize were 174.3, 170.0, and 141.3 cm, respectively, when no biochar was applied. At maturity stage, under control condition (80% of FC), 60%

**Tasseling stage (cm) Cob initiation stage (cm) Maturity stage (cm)**

**40% of FC**

**Control 60% of FC**

**40% of FC**

**Control 60% of FC**

0 164.0cd 161.6 d 136.6 f 174.3cd 170.0d 141.3 f 175.3c 173.0c 154.0 e 5 172.6bc 172.0 bc 139.3 f 175.6cd 174.6cd 145.3 f 180.6bc 178.3bc 156.6de 10 174.3b 174.0 b 151.3 e 186.6b 182.6bc 157.6 e 186.6b 185.6b 163.0 d 20 190.0a 184.3 a 165.6bcd 195.6a 190.3ab 169.0 d 202.3a 195.6a 173.3 c

CV (%) 3.5 2.9 2.9

*Effect of rice husk biochar on plant height in maize at reproductive stages under drought conditions.*

plant height [20].

**Biochar doses (t/ha)**

**Table 2.**

**61**

**Table 1.**

**Biochar doses (t/ha)**

**Control 60% of FC**

*DOI: http://dx.doi.org/10.5772/intechopen.88824*

*Figure having similar letter did not vary significantly.*

**40% of FC**

*Amelioration of Drought Tolerance in Maize Using Rice Husk Biochar*

**under drought stress**

**Control 60% of FC**

*Figure having similar letter did not vary significantly.*

**40% of FC**

Biochar is charcoal formed from the thermal decomposition of biomass in a lowor zero-oxygen environment and at high temperatures (<700°C), and biochar production and application in soils has a very high potential for the expansion of sustainable agricultural systems and also for global climate change mitigation [10]. Experimental evidence so far shows that incorporation of biochar to soil enhanced soil water-holding capacity, improved soil water permeability, and improved saturated hydraulic conductivity (SHC) [11], modification in soil bulk density [12], and modified aggregate stability [13]. Biochar has the potential to increase the availability of plant nutrient [14]. Furthermore, research has found that biochar improves crop productivity and mitigates drought, salinity, acidity, and toxic metal stresses that are commonly associated with plant stress [15]. Biochar application increases growth and biomass of drought-stressed plants as well as increased photosynthesis [16].

Therefore, the objectives of this manuscript are to know the effects of rice husk biochar to mitigate drought effects on the growth, physiology, and yield of maize at drought conditions.

### **2. Mitigating effects of biochar on drought stress in maize**

## **2.1 Effect of rice husk biochar on plant height of maize at vegetative stages under drought stress**

Plant height differences of maize at vegetative stages indicated that plant height varied due to different doses of biochar under drought conditions (**Table 1**).

At the sixth leaf stage, under control condition (80% of FC), 60% of field capacity, and 40% of field capacity, highest plant heights of maize were 44.8, 43.8, and 42.2 cm, respectively, when biochar was applied at 20 t/ha, and lowest plant heights of maize were 39.4, 39.1, and 38.7 cm, respectively, when no biochar was applied. At the 10th leaf stage, under control condition (80% of FC), 60% of field capacity, and 40% of field capacity, highest plant heights of maize were 95.4, 93.0, and1.2 cm, respectively, when biochar was applied at 20 t/ha, and lowest plant heights of maize were 90.4, 89.5, and 80.2 cm, respectively, when no biochar was applied. At the 14th leaf stage, under control condition (80% of FC), 60% of field capacity, and 40% of field capacity, highest plant heights of maize were 169.3,


*Amelioration of Drought Tolerance in Maize Using Rice Husk Biochar DOI: http://dx.doi.org/10.5772/intechopen.88824*

#### **Table 1.**

Increase in substances such as proline can be one of the major molecular responses to drought stress [6]. Drought stress-induced free radicals cause lipid peroxidation

Maize is the third most important cereal crops in Bangladesh, after rice and wheat. It can be cultivated year round. The crop is high yielding and rich in nutrient and has diversified uses. The demand of maize in Bangladesh is primarily from the commercial feed processing industry. This industry is the driving force of maize sector, using 80% of its aggregate maize production (excluding imports), and statistically, the poultry sector (a significant representative of feed industry) is growing at an average rate of 23% per year [8].Therefore, production of maize needs to be increased. However maize production is severely affected by drought stress. Water absorption, imbibition, and metabolic enzymatic activation are hindered under limited water availability which reduces the maize grain germination. Root and shoot elongations are parameters of seedling growth, and these are subjected to reduction by drought stress. At seedling stage in maize, reduction in shoot elongation is more than root elongation under drought stress [9]. Application of biochar is such technology which can mitigate adverse effects of drought stress

Biochar is charcoal formed from the thermal decomposition of biomass in a low-

Therefore, the objectives of this manuscript are to know the effects of rice husk biochar to mitigate drought effects on the growth, physiology, and yield of maize at

**2. Mitigating effects of biochar on drought stress in maize**

**2.1 Effect of rice husk biochar on plant height of maize at vegetative stages**

varied due to different doses of biochar under drought conditions (**Table 1**). At the sixth leaf stage, under control condition (80% of FC), 60% of field capacity, and 40% of field capacity, highest plant heights of maize were 44.8, 43.8, and 42.2 cm, respectively, when biochar was applied at 20 t/ha, and lowest plant heights of maize were 39.4, 39.1, and 38.7 cm, respectively, when no biochar was applied. At the 10th leaf stage, under control condition (80% of FC), 60% of field capacity, and 40% of field capacity, highest plant heights of maize were 95.4, 93.0, and1.2 cm, respectively, when biochar was applied at 20 t/ha, and lowest plant heights of maize were 90.4, 89.5, and 80.2 cm, respectively, when no biochar was applied. At the 14th leaf stage, under control condition (80% of FC), 60% of field capacity, and 40% of field capacity, highest plant heights of maize were 169.3,

Plant height differences of maize at vegetative stages indicated that plant height

or zero-oxygen environment and at high temperatures (<700°C), and biochar production and application in soils has a very high potential for the expansion of sustainable agricultural systems and also for global climate change mitigation [10]. Experimental evidence so far shows that incorporation of biochar to soil enhanced soil water-holding capacity, improved soil water permeability, and improved saturated hydraulic conductivity (SHC) [11], modification in soil bulk density [12], and modified aggregate stability [13]. Biochar has the potential to increase the availability of plant nutrient [14]. Furthermore, research has found that biochar improves crop productivity and mitigates drought, salinity, acidity, and toxic metal stresses that are commonly associated with plant stress [15]. Biochar application increases growth and biomass of drought-stressed plants as well as increased

and membrane deterioration in plants [7].

*Maize - Production and Use*

on maize.

photosynthesis [16].

drought conditions.

**60**

**under drought stress**

*Effect of rice husk biochar on plant height of maize at vegetative stages under drought conditions.*

154.3, and 145.0 cm, respectively, when biochar was applied at 20 t/ha, and lowest plant heights of maize were 150.6, 139.0, and 134.3 cm, respectively, when no biochar was applied. So it is clear that plant height is affected by drought conditions and application of rice husk biochar mitigated the effect of drought condition by increasing plant height. Similar result was reported in maize by [17]. Biochar promoted plant height of maize under drought conditions [18]. By affecting cell turgidity, drought impaired plant height [19]. Application of biochar can increase soil water-holding capacity which increased tissue water status and ultimately increased plant height [20].

## **2.2 Effect of rice husk biochar on plant height of maize at reproductive stages under drought stress**

Plant height differences of maize at reproductive stages indicated that plant height varied due to different doses of biochar under drought conditions (**Table 2**).

At tasseling stage, under control condition (80% of FC), 60% of field capacity, and 40% of field capacity, highest plant heights of maize were 190.0, 184.3, and 165.6 cm, respectively, when biochar was applied at 20 t/ha, and lowest plant heights of maize were 164.0, 161.6, and 136.6 cm, respectively, when no biochar was applied. At cob initiation stage, under control condition (80% of FC), 60% of field capacity, and 40% of field capacity, highest plant heights of maize were 195.6, 190.3, and 169.0 cm, respectively, when biochar was applied at 20 t/ha, and lowest plant heights of maize were 174.3, 170.0, and 141.3 cm, respectively, when no biochar was applied. At maturity stage, under control condition (80% of FC), 60%


#### **Table 2.**

*Effect of rice husk biochar on plant height in maize at reproductive stages under drought conditions.*

of field capacity, and 40% of field capacity, highest plant heights of maize were 202.3, 195.6, and 173.3 cm, respectively, when biochar was applied at 20 t/ha, and lowest plant heights of maize were 175.3, 173.0, and 154.0 cm, respectively, when no biochar was applied. Drought conditions affected plant height, and biochar application increased plant height under drought conditions. Similar result was reported in maize by [21]. Addition of biochar improved plant height [22]. In rice, drought stress during the vegetative stage greatly reduced the plant height; [23] and [24] found that biochar increased the plant height of maize.

maturity of maize plant were varied significantly at different doses of biochar under

*Amelioration of Drought Tolerance in Maize Using Rice Husk Biochar*

Under control condition (80% of FC), 60% of field capacity, and 40% of field capacity, highest days to maturity of maize were 136, 135, and 133 days, respectively, when biochar was applied at 20 t/ha, and lowest days to flowering of maize were 131, 130, and 128 days, respectively, when no biochar was applied. Application of biochar increased the water-holding capacity of silty sand under maize cultivation in pots; [26] and [27] reported that biochar helped in maintaining normal physiological functions including maturity of wheat under saline conditions. [28] observed that biochar

**2.5 Effect of rice husk biochar on relative water content (RWC), water uptake capacity (WUC), and water saturation deficit (WSD) in maize under**

Relative water content of maize plant was reduced significantly at drought stress conditions because of low water content of soil. Application of rice husk biochar at different doses helped to increase water-holding capacity of soil under drought conditions and thereby increased relative water content of maize plant (**Table 3**). Under control condition (80% of FC), 60% of field capacity, and 40% of field capacity, highest RWC of maize were 83.37, 79.86, and 78.32%, respectively, when biochar was applied at 20 t/ha, and lowest RWC of maize were 66.93, 63.75, and

Water saturation deficit of maize plant was increased significantly at drought stress conditions, and it is varied with different doses of biochar under drought conditions (**Table 3**).Under control condition (80% of FC), 60% of field capacity, and 40% of field capacity, lowest WSD of maize were 16.6, 20.1, and 21.1%, respectively, when biochar was applied at 20 t/ha, and highest WSD of maize were

Water uptake capacity of maize plant was increased significantly under drought stress because soil contained low moisture to be uptaken by plant. WUC depended

*Effect of rice husk biochar on days to maturity of maize under drought conditions. Bar indicates LSD at 5% level*

application increased tomato growth and life cycle under saline conditions.

62.25%, respectively, when no biochar was applied.

33.0, 36.2, and 37.7%, respectively, when no biochar was applied.

drought conditions (**Figure 2**).

*DOI: http://dx.doi.org/10.5772/intechopen.88824*

**drought stress**

**Figure 2.**

**63**

*of significance.*
