Photosynthetic characteristics of subtending leaves and their relationships with soybean pod development under heat, drought and combined stresses

Abstract

Soybean is usually grown under rain‐fed conditions, and long‐term drought stress often occurs with short‐term heat stress. This study aimed to investigate changes in the photosynthetic characteristics of subtending leaves and their relationships with pod development under short‐term heat, long‐term drought and their combined stresses. Short‐term heat stress lasted for 5 days began at R5 stage, and long‐term drought stress lasted from R5 stage until maturity, respectively. No significant effect was observed on pod development under short‐term heat stress alone due to unaffected net photosynthetic rate after treatment and PSII recovery after the heat stress release. Except that the reduction of sucrose content had been brought forward from 12 to 5 days after treatment under combined stresses, application of combined stresses caused similar responses to long‐term drought stress alone on the photosynthetic characteristics of subtending leaves and pod development, but more pronounced under combined stresses. Reduced pod weight and seed weight per pod under long‐term drought stress alone or combined stress due to a decrease in the net photosynthetic rate and production of sucrose and starch, especially after 19 days of treatment. Findings from this study demonstrate that under combined stress, long‐term drought stress had a dominant effect on the photosynthetic performance of subtending leaves and pod development over short‐term heat stress; moreover, even short‐term heat stress also exacerbates the negative effects of long‐term drought stress.

Negative Synergistic Effects of Drought and Heat During Flowering and Seed Setting in Soybean

“…Paradigm shift occurring under combined drought and heat stress compared to the individual stressors is gaining prominence in soybean and other crops (Zandalinas et al, 2018; Ergo et al, 2018; Lawas et al, 2018; Zandalinas et al, 2020; Cohen et al, 2021a; b; Bheemanahalli et al, 2022b). Recent research shows that soybeans had a synergistic effect of combined heat and drought stresses, particularly affecting source-sink balance and yield (Du et al, 2023). The present results show that the interactive heat and drought in soybeans had a higher impact on physiology, yield, and seed composition compared to single stress at the cultivar level.…”

24‐Epibrassinolide promotes activation of physiological compensation mechanisms in response to drought stress and rehydration and improves yield in soybean

“…Water deficit is an important factor that limits the yield of different agricultural crops. Drought stress in soybean plants, one of the most widespread crops in the world and sensitive to drought stress, can seriously damage the antioxidant systems of plants, reduce chlorophyll levels, affect photosynthetic activity and also damage membrane stability, which results in greater loss of biomass and yield (Buezo et al, 2019; Dong et al, 2019; Du et al, 2022). Studies with different crops suggest that BRs not only alleviate these deleterious effects of drought stress but also improve plant growth and yield (Anwar et al, 2018; Desoky et al, 2021; Khan et al, 2021).…”

“…Water restriction can induce a series of injuries in soybean crop, with direct impacts on leaf gas exchanges, inhibition of photosynthesis and changes in plant metabolism, which causes reductions in plant growth, biomass and grain yield (Buezo et al, 2019; Du et al, 2022). Under water deficit and high luminosity conditions, plants experience disturbances due to excess electrons in the transport systems of the photosystems, which causes over‐excitation of the reaction centers of photosystems II (PSII) and I (PSI), which reduces the efficiency of light energy conversion (Wang et al, 2018), increasing the production of reactive oxygen species (ROS) and oxidative stress in the plant (Dong et al, 2019).…”