Abstract
Traditional mulch material (farmyard manure) has long been used in agriculture. However, recent developments have also introduced the scientific community and farmers to advanced chemicals such as potassium polyacrylamide (KPAM), which has revolutionised the concept of the soil water-holding capacity to many compared with other materials being used. To compare the effect of different organic and inorganic soil amendment materials under water stress conditions, a two-year (2018 and 2019) field study was conducted. The main plots consisted of irrigation treatments, i.e., I0 (control irrigation), I1 (drought-induced by skipping irrigation at the 4th leaf stage), and I2 (drought-induced by skipping irrigation at the anthesis stage). The subplots included a control treatment and soil amended with different conditioners such as potassium polyacrylamide (KPAM, 30 kg/ha), farmyard manure (FYM, 4 tons/ha), and biochar (10 tons/ha); these were mixed thoroughly with the soil before sowing. The results showed a significant reduction in the water relation parameters (water potential up to 35.77% and relative water content up to 21%), gas exchange parameters (net CO2 assimilation rate up to 28.85%, stomatal conductance up to 43.18%, and transpiration rate up to 49.07%), and yield attributes (biological yield up to 8.45% and grain yield up to 32.22%) under drought stress conditions. In addition, water stress also induced an increase in the synthesis of osmoprotectants (proline up to 77.74%, total soluble sugars up to 27.43%, and total free amino acids up to 11.73%). Among all the soil conditioners used, KPAM significantly reduced the negative effects of drought stress on the wheat plants. Thus, it could be concluded that the use of soil conditioners is a promising method for dealing with the negative consequences of drought stress for achieving sustainable crop yields.
Highlights
Drought stress is one of the most devastating yield-limiting factors in field crops, for cereals such as wheat, rice, and maize
The drought induced by skipping irrigation, at the anthesis stage, had more detrimental effects in terms of the water potential (−1.41 and −1.46 MPa, respectively) and relative water content (58.44% and 56%, respectively)
For the soil amendment treatments, KPAM had the highest values of water potential, relative water content, net CO2 assimilation rate, stomatal conductance, and transpiration rate compared with the control, Farmyard manure (FYM), and biochar
Summary
Drought stress is one of the most devastating yield-limiting factors in field crops, for cereals such as wheat, rice, and maize. Drought stress is reported to negatively affect global wheat production and results in economic losses every year. Low water availability during critical stages of wheat growth has a direct impact on the performance of the crop as it reduces the biomass accumulation and chlorophyll synthesis [3]. Drought-induced alterations in the plant–water relations reduce carbon dioxide assimilation and increase oxidative stress at the cellular level [5,6]. Such alterations inhibit enzymatic and hormonal activities, leading to a reduced wheat growth and yield under water-stressed conditions [5,6]. Different physiological and biochemical processes such as transpiration, photosynthesis, stomatal conductance, translocation, and source-sink relations are affected, reducing the grain yield [8]
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