**2.8 Effect of rice husk biochar on SPAD value of maize at vegetative stages under drought stress**

At vegetative stage SPAD value of maize plant was reduced significantly at drought stress conditions. SPAD value varied with different doses of biochar under drought conditions (**Table 5**).

At the 6th leaf stage of maize after under control condition, highest SPAD value (30.7) was found when biochar was applied at 20 t ha<sup>1</sup> , and it was lowest (25.3) when no biochar was applied. Under 60% of field capacity, highest SPAD value (30.5) was found when biochar was applied at 20 t/ha, and it was lowest (23.7) when no biochar was applied. Under 40% of field capacity, highest SPAD value (29.5) was found when biochar was applied at 20 t/ha, and it was lowest (20.4) when no biochar was applied. At the 10th leaf stage of maize after under control condition, highest SPAD value (33.3) was found when biochar was applied at 20 t/ha, and it was lowest (29.3) when no biochar was applied. Under 60% of field capacity, highest SPAD value (30.2) was found when biochar was applied at 20 t/ha, and it was lowest (29.3) when no biochar was applied. Under 40% of field capacity, highest SPAD value (29.8) was found when biochar was applied at 20 t/ha and at 5 t/ha (29.4), and it was lowest (29.0) when no biochar was applied. At the 14th leaf stage of maize after under control condition, highest SPAD value (35.3) was found when biochar was applied at 20 t/ha, and it was lowest (29.5) when no biochar was applied. Under 60% of field capacity, highest SPAD value (32.0) was found when biochar was applied at 20 t/ha, and it was lowest (27.7) when no biochar was applied. Under 40% of field capacity, highest SPAD value (31.8) was found when biochar was applied at 20 t/ha, and it was lowest (27.2) when no biochar was applied. It indicates that the longer the exposure to drought stress, the higher the decreases of the SPAD value. The decrease of SPAD reading under drought conditions is reported by [36]. [37] showed that biochar may alleviate water stress in plants and increased SPAD value.

When biochar was applied at different doses, SPAD value was increased. At tasseling stage of maize under control condition (80% of FC), 60% of field capacity, and 40% of field capacity, highest SPAD values were 33.5, 31.2, and 30.7, respectively, when biochar was applied at 20 t/ha, and lowest SPAD values were 30.2, 28.0, and 27.8, respectively, when no biochar was applied. At cob initiation stage of maize under control condition (80% of FC), 60% of field capacity, and 40% of field capacity, highest SPAD values were 31.3, 31.0, and 30.7, respectively, when biochar was applied at 20 t/ha, and lowest SPAD values were 28.2, 27.6, and 27.1, respectively, when no biochar was applied. Similar result was reported by Mannan et al. (2016) in soybean plant under salinity stress due to poultry litter biochar. With increasing drought stress levels, SPAD readings were decreased [38]. [39] reported

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

**Biochar doses (t/ha) Tasseling stage Cob initiation stage**

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

CV (%) 4.4 5.0

 30.2bc 28.0cd 27.8d 28.2b–d 27.6cd 27.1d 30.6b 29.4c–d 29.2b–d 29.8a–c 29.3a–d 29.2a–d 30.9b 29.8b–d 29.7b–d 30.7ab 29.5a–d 29.5a–d 33.5a 31.2b 30.7b 31.3a 31.0a 30.7ab

**Control 60% of FC 40% of FC Control 60% of FC 40% of FC**

**2.10 Effect of rice husk biochar on proline of maize under drought stress**

Proline is a kind of stress protein. Proline accumulation under stress condition occurred because the Calvin cycle of photosynthesis is affected by drought; as a result N content could not be properly metabolized. In drought soil biochar increases photosynthesis and proper metabolism of N content. Proline content of maize varied significantly with different doses of biochar under drought conditions

Under control condition (80% of FC), 60% of field capacity, and 40% of field capacity, lowest proline contents were 1.1, 1.1, and 3.2 μ mole/g, respectively, when biochar was applied at 20 t/ha, and highest proline contents were 1.8, 2.9, and 6.1 μ mole/g, respectively, when no biochar was applied. [40] reported biochar decreased proline content in plants. [41] marked drought stress caused overproduction of proline content. [42] also reported biochar increased photosynthesis in grape leaves.

**2.11 Effect of rice husk biochar on dry weight of cob sheath, leaf, and stem of**

A major effect of drought is reduction in photosynthesis, which is associated with reduction in food production and ultimately reduced dry weight of plant parts. Dry weight of cob sheath, leaf, and stem of maize is greatly affected by drought conditions. Application of rice husk biochar increased dry matter of cob sheath, leaf, and stem of maize under drought conditions. Dry weight of cob sheath, leaf, and stem of maize varied significantly with different doses of biochar under

biochar increased soil moisture level and maize yield.

*Figure having similar letter did not vary significantly.*

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

**maize under drought stress**

drought conditions (**Table 7**).

**67**

(**Figure 4**).

**Table 6.**
