*4.2.8. Number of grains per spike*

*4.2.6. Spike length*

20 Global Wheat Production

*4.2.7. Spikelets per spike*

Spike length of the both wheat genotypes differed considerably due to their genetic characteristics (**Table 14**). The results illustrated that the higher spike length was recorded for the NARC-2009 (9.5 cm) against Sehar-06 (8.7 cm). The difference between both genotypes was 8%. While discussing about treatments, maximum spike length was recorded for T7 (10.2 cm), while the minimum spike length was noticed under T4 (8.2 cm). There was 14% difference among highest and lowest treatments. Similarly, the interactive effect was significant. Highest spike length was recorded for NARC-2009 under T7 (10.7 cm) while lowest spike length was observed for Sehar-06 under T4 (7.89 cm). There was 21% variation for spike length among highest and lowest interactions. Root signaling played a vital role in the development of the good source-sink relationship. Maximum spike length is produced as translocation of more photo-assimilates takes place efficiently from source to sink. Balanced application of P fertilizers and their availability might be another reason of spike length increment. Our findings were in accordance with Dewal and Pareek [50] and Memon [52] who reported increment in spike length with the addition of P fertilizers. Our results were also confirmed by the findings

Spikelets per spike of the both wheat genotypes varied noticeably due to their genetic characteristics (**Table 15**). The results depicted that the higher spikelets per spike was observed for the NARC-2009 (2.7) against Sehar-06 (2.5). The difference between both genotypes was 8%. As regards to treatments, maximum spike length was recorded for T7 (2.9), while the minimum spike length (2.4) was noticed under T4. There was 15% difference among highest and lowest treatments. Similarly, the interactive effect was significant. Highest spike length was recorded for NARC-2009 under T7 (3.1) while lowest spikelets per spike were observed for Sehar-06 under T4 (2.3). There was 22% variation for spikelets per spike among highest and lowest interactions. The variation in number of spikelets per spike might be due to balanced

**Treatments/genotypes Sehar-06 NARC-2009 Mean** T1 2.4ab 2.6ab 2.5AB T2 2.6ab 2.9ab 2.8AB T3 2.4ab 2.6ab 2.5AB T4 2.3b 2.ab 2.4B T5 2.4b 2.6ab 2.5AB T6 2.4ab 2.6ab 2.5AB T7 2.8ab 3.1a 2.9A T8 2.6ab 2.9ab 2.8AB

Mean 2.5B 2.7A

LSD for G 0.2234 LSD for T 0.4867 LSD for G × T 0.6883

**Table 15.** Spikelets per spike for both genotypes at maturity.

of Hussain [53] who reported increase in spike length due to P addition.

Both the genotypes varied potentially for number of grains per spike (**Table 16**). NARC-2009 exhibited maximum number of grains per spike (23.56) than Sehar-06 (21.45). There was 9% difference among both the genotypes for number of grains per spike. All the treatments showed significant difference for number of grains per spike. Highest number of grains per spike was recorded for T7 (26.99) while lowest number of grains per spike was recorded for T4 (20.07). In the same way, the interactive effect was also found significant. Maximum number of grains per spike was recorded for NARC-2009 under T7 (28.21) whereas, minimum number of grains per spike was recorded for Sehar-06 under T4 (19.21). Root signaling played a vital role in enhancing number of grains per spike. By applying phosphorus root signaling enhanced in the crop. Sufficient availability and the uptake of P facilitate the crop to grow more rapidly and it also enables the crop to capture more solar radiations and consequently more number of grains per spike produced. Insufficiency of P undersized the growth of stem as well as whole plant. However, the addition of P encourages the plant growth which results in increase in number of spikelets per spike due to better root signaling. With the increase in number of spikelets per spike, number of grains per spike also increased. The results of present study were in line with Ali et al. [54] and Dewal and Pareek [50] who observed the reduction in number of grains per


**Table 16.** Number of grains per spike for both genotypes at maturity.

spike with the reduction in quantity of P applied. Similar results were reported by Poulsen et al. [55] who suggested that P fertilization maximizes number of grains per spike in wheat crop.

#### *4.2.9. Spike weight*

Spike weight of the both wheat genotypes differed considerably due to their genetic characteristics (**Table 17**). The results depicted that the higher spike weight was recorded for the NARC-2009 (0.52 g) against Sehar-06 (0.46 g). The difference between both genotypes was 11%. Similarly, all the treatments differed potentially for spike weight. Maximum spike weight was recorded for T7 (0.55 g) followed by T8 (0.53 g), while the minimum spike weight was noticed under T1 (0.43). There was 21% difference among highest and lowest treatments. Similarly, the interactive effect was significant for spike weight. Highest spike weight was recorded for NARC-2009 under T7 (0.57 g) while lowest spike weight was observed for Sehar-06 under T1 (0.41 g). There was 28% variation for spike weight among highest and lowest interactions. Increased spike weight might be due to the adequate accessibility and uptake of P by crop plants. In stressed environment phosphorus played role to enhance root signaling. Due to uptake of P in adequate amount maximum numbers of fertile tillers were produced and the spike length, number of spikelet per spike and grains per spike also increased due to photosynthesis, energy storage, transfer, cell division as well as cell elongation so ultimately it results in increase in grain yield. The findings of current study corroborate the conclusions of Al-Karaki and Al-Omoush, [56], and Mehdi et al. [57] who reported that application of P increases spike weight which ultimately enhanced grain yield. Our results were not in accordance with Somayeh and Bahram [58], who reported enhanced spike weight by addition of phosphorus.

fallowed by T8 (4.25 g) whereas, lowest hundred grain weight (3.51 g) observed for treatment T1. There was 19% difference among T7 and T1 for hundred grain weight. Similarly, there was significant difference among all the interactive effects at 1% P level. Maximum hundred grain weight observed for genotype NARC-2009 (4.58 g) under T7 whereas, minimum hundred grain weight recorded for Sehar-06 under T1 (3.27 g). There was 28% difference among maximum and minimum interactive effects for hundred grain weight. Grain weight is directly a measure of final productivity of the field crop. Greater the grain weight greater will the economical yield. Phosphorus applications in the stressed environment enhanced root signaling which ultimately enhanced grain weight. The reason of increased hundred grain weight might be due to provision of available phosphates to the plants in sufficient amount. Availability of P encourages root development and stimulates growth at seedling stage, so it promotes the quick establishment of seedling. It also accelerates leaf development and promotes faster growth of shoots and roots. As addition of phosphorus encourages normal growth of plant, ultimately it increased hundred grain weight. Similar results were found by Dewal and Pareek [50] and Memon [52] who observed considerable increase in grain weight in wheat by the addition of phosphorus.

**Treatments Sehar-06 NARC-2009 Mean** T1 3.27i 3.74e–h 3.51E T2 3.41hi 3.91d–f 3.67DE T3 3.48g–i 3.99de 3.74DE T4 3.59f–i 4.11cd 3.85CD T5 3.77e–g 4.22b–d 3.99BC T6 3.96de 4.40a–c 4.19AB T7 4.17bcd 4.58a 4.38A T8 4.01de 4.48ab 4.25A

Effect of Phosphorus on Root Signaling of Wheat under Different Water Regimes

http://dx.doi.org/10.5772/intechopen.75806

23

Mean 3.7125 4.1829

**Table 18.** Hundred grain weight for both genotypes at maturity.

LSD for G 0.1193 LSD for T 0.2386 LSD for G × T 0.3376

Root architecture is a highly plastic and environmentally responsive trait that enables plants to counteract nutrient scarcities with different forging strategies. Root-specific traits such as root system architecture, sensing of edaphic stress and root-shoot communication can be exploited to improve resource capture (water and nutrients) and plant development under resource-limited conditions. The ability of plants to respond appropriately to nutrient availability is of fundamental importance for their adaptation to the environment. These signals trigger molecular mechanisms that modify cell division and cell differentiation processes within the root and have a profound impact on root system architecture. Important developmental processes, such as root-hair formation, primary root growth and lateral root formation, are particularly sensitive to changes in the internal and external concentration

**5. Conclusion**

#### *4.2.10. Hundred grain weight*

Wheat genotypes due to their genetic behavior differed considerably for hundred grain weight at (**Table 18**). Highest hundred grain weight (4.18 g) calculated for genotype NARC-2009 whereas, lowest hundred grain weight (3.71 g) calculated for genotype Sehar-06. Both the genotypes differed 11% for hundred grain weight. All the treatments varied significantly for hundred grain weight. Highest hundred grain weight (4.38 g) recorded for treatment T7


**Table 17.** Spike weight for both genotypes at maturity.

Effect of Phosphorus on Root Signaling of Wheat under Different Water Regimes http://dx.doi.org/10.5772/intechopen.75806 23


**Table 18.** Hundred grain weight for both genotypes at maturity.

fallowed by T8 (4.25 g) whereas, lowest hundred grain weight (3.51 g) observed for treatment T1. There was 19% difference among T7 and T1 for hundred grain weight. Similarly, there was significant difference among all the interactive effects at 1% P level. Maximum hundred grain weight observed for genotype NARC-2009 (4.58 g) under T7 whereas, minimum hundred grain weight recorded for Sehar-06 under T1 (3.27 g). There was 28% difference among maximum and minimum interactive effects for hundred grain weight. Grain weight is directly a measure of final productivity of the field crop. Greater the grain weight greater will the economical yield. Phosphorus applications in the stressed environment enhanced root signaling which ultimately enhanced grain weight. The reason of increased hundred grain weight might be due to provision of available phosphates to the plants in sufficient amount. Availability of P encourages root development and stimulates growth at seedling stage, so it promotes the quick establishment of seedling. It also accelerates leaf development and promotes faster growth of shoots and roots. As addition of phosphorus encourages normal growth of plant, ultimately it increased hundred grain weight. Similar results were found by Dewal and Pareek [50] and Memon [52] who observed considerable increase in grain weight in wheat by the addition of phosphorus.
