Effect of simultaneous shade and drought stress on morphology, leaf gas exchange, and yield parameters of different soybean cultivars

Abstract

An interactive effect of simultaneous shade and drought stress on drought-tolerant and drought-sensitive cultivars of soybean was studied. As drought stress intensified, the net photosynthetic rate decreased in both cultivars due to reduced leaf area, relative water content, transpiration rate, stomatal conductance, chlorophyll content, and Rubisco activity which ultimately led to yield reduction. Moreover, the chlorophyll fluorescence parameters also decreased. Interestingly, a moderate shade was found helpful in alleviating the adverse effects of drought stress, specifically in resistant cultivar N12 where seed yield improved significantly under moderate drought conditions in contrast to the cultivar C103. In summary, the effect of drought stress on soybean depended on the irradiance conditions and shade could enhance soybean drought resistance, although this resistance was cultivar dependent. With appropriate cultivar selection, a moderate shade can help optimize yield and improve the performance of drought-exposed soybean.

Crop responses and management strategies under shade and drought stress

“…When discussing the yield components, shade and drought stress occurring individually generally have negative effects on plant yield, however, when both the stresses occur simultaneously, the effect on yield is often not the same. Shade stress, in some cases, may serve useful to alleviate negative consequences of water deficit stress on the yield of crops as reported earlier in soybean (Zhang et al 2011, Shafiq et al 2020.…”

“…Plant photosynthetic response to co-occurring stresses might also vary in comparison to individual stress. Transpiration rate (E), stomatal conductance (gs), and net photosynthetic rate (PN) in plants did not decrease when exposed to drought stress (55 ± 2% field capacity) and low irradiance (PPFD = 500-600 μmol m -2 s -1 at noon) whereas a decrease was observed in plants that were kept in medium or high irradiance which depicts a positive role of shade under drought conditions (Shafiq et al 2020) and supports the facilitation hypothesis (Holmgren 2000). The results of this research propose that the degree of influence of drought stress on a plant's photosynthetic capacity depends on the irradiance in the environment.…”

“…Research work on shade (Chen et al 2019(Chen et al , 2020Ferroni et al 2021) and drought (Lawlor and Tezara 2009, Zivcak et al 2014a, Anjum et al 2017, occurring as individual stress factors in several crops, is well cited in the literature. However, not much attention has been given to their combined effects and whether the crop responses to both of these stresses are shared or unique also remains ambiguous (Shafiq et al 2020). An understanding of the responses of plants to cooccurring stress factors is necessary to enhance plants' adaptation under field conditions.…”

Exogenous application of 5-aminolevulinic acid alleviated damage to wheat chloroplast ultrastructure under drought stress by transcriptionally regulating genes correlated with photosynthesis and chlorophyll biosynthesis

“…Drought stress can significantly reduce the electron transfer activity of chloroplast, thus reducing the photosynthetic rate (Shafiq et al 2020;Asghar et al 2020). This may be because the lack of water causes the stomata of plants to close, reducing the entry of CO 2 , leading to a decrease in intercellular CO 2 concentration and a reduction in carbon fixation (Iqbal et al 2019).…”

Nitrogen fertilization coupled with foliar application of iron and molybdenum improves shade tolerance of soybean under maize-soybean intercropping

“…Shade has numerous effects on plant life, resulting in diverse and novel environmental conditions. As a result, plant growth is negatively impacted, with decreased biomass, stem diameter, leaf area and thickness, stem breaking strength, and eventually yield ( Hussain et al., 2019 ; Shafiq et al., 2020 ). Under intercropping, shade from one companion plant limits the photosynthesis in legumes and is considered a major threat to legume growth ( Gitari et al., 2018 ; Nyawade et al., 2021 ; Blessing et al., 2022 ; Cheng et al., 2022 ).…”