The impact of straw application on growth dynamics and proline accumulation in drought-stressed rice

The frequent occurrence of unpredictable extreme droughts necessitates investigating measures to mitigate their impacts, as drought may occur at any growth phase of rice. This study evaluated the efficiency of straw applications to conserve soil moisture and mitigate the negative effect of drought stress on rice in tropical riparian wetlands. Rice straw was applied as organic matter (S1) and as mulch (S2) and then subjected to drought stress during early vegetative (D1), late vegetative (D2), and generative (D3) phases. The result of this study showed that the utilization of straw slowed down the water loss through evaporation as indicated by soil moisture. However, both rice straw applications, organic matter and mulch, were inefficient in maintaining the optimum plant growth when the soil moisture declined to < 10%. Drought stress at the early vegetative phase reduced the number of leaves by 63.68%, the number of tillers by 50.58%, and the total leaf area by 72.36%. Drought stress at the early vegetative phase also delayed flowering time for 11 days. Meanwhile, drought stress during the generative phase reduced the number of filled spikelets by 45.18% and increased sterile spikelets to 247.05%, which significantly reduced the yield. Plants that experienced drought stress during the vegetative and generative phases eventually increased the proline content by about 10 times (18.47 mmol g-1) compared to unstressed plants (1.62 mmol g-1). Straw mulching is recommended for mild to moderate droughts, but additional methods are needed to maintain soil moisture below 10%.