Leaf Wilting Movement Can Protect Water-Stressed Cotton (Gossypium hirsutum L.) Plants Against Photoinhibition of Photosynthesis and Maintain Carbon Assimilation in the Field

Abstract

Under severe water stress, leaf wilting is quite general in higher plants. This passive movement can reduce the energy load on a leaf. This paper reports an experimental test of the hypothesis that leaf wilting movement has a protective function that mitigates against photoinhibition of photosynthesis in the field. The experiments exposed cotton (Gossypium hirsutum L.) to two water regimes: waterstressed and well-watered. Leaf wilting movement occurred in water-stressed plants as the water potential decreased to −4.1 MPa, reducing light interception but maintaining comparable quantum yields of photosystem II (PS II; Yield for short) and the proportion of total PS II centers that were open (qP). Predrawn F v /F m (potential quantum yield of PS II) as an indicator of overnight recovery of PS II from photoinhibition was higher than or similar to that in wellwatered plants. Compared with water-stressed cotton leaves for which wilting movement was permitted, water-stressed cotton leaves restrained from such movement had significantly increased leaf temperature and instantaneous CO 2 assimilation rates in the short term, but reduced Yield, qP, and F v /F m . In the long term, predrawn F v /F m and CO 2 assimilation capacity were reduced in water-stressed leaves restrained from wilting movement. These results suggest that, under water stress, leaf wilting movement could reduce the incident light on leaves and their heat load, alleviate damage to the photosynthetic apparatus due to photoinhibition, and maintain considerable carbon assimilation capacity in the long term despite a partial loss of instantaneous carbon assimilation in the short term.

Field-Based High-Throughput Plant Phenotyping Reveals the Temporal Patterns of Quantitative Trait Loci Associated with Stress-Responsive Traits in Cotton

“…In comparison, NDVI in the WW plots remained high over the course of a day, because canopy geometry was more stable. This was because the leaves of plants under WW conditions were at higher turgor pressure and could maintain a perpendicular orientation to incoming light, but, under WL conditions, the water potential of leaves was reduced, causing a loss of turgor pressure that led to wilting ( Zhang et al 2010 ). Because the angular distribution of leaf area in the canopy was altered to expose more soil in the sensor’s field of view under WL conditions, the amount of near-infrared light reflected was decreased, leading to lower NDVI values.…”

Leaf paraheliotropism in Styrax camporum confers increased light use efficiency and advantageous photosynthetic responses rather than photoprotection

“…doi:10.1016/j.envexpbot.2010.10.012 which reinforces the photo-protective role of paraheliotropism. Even the leaf wilting movement of non-leguminous species, such as cotton plants, confers photo-protection and maintains carbon assimilation (Zhang et al, 2010).…”

Na+ accumulation alleviates drought stress induced photosynthesis inhibition of PSII and PSI in leaves of Medicago sativa

“…The ability to maintain photosynthesis under drought stress plays an important role in alleviating the yield and quality reduction in crop plants faced with drought. Drought conditions lead plants to significantly reduce the stomatal conductance of leaves to reduce water loss (Yi et al 2016), and photosynthetic capacity is often also reduced with decreased stomatal conductance (Zhang et al 2010). PSII and PSI are the main photosynthetic systems that are inhibited under adverse conditions (Zhang et al 2020a(Zhang et al , 2020b, and drought often leads to a decrease in the photochemical activity of PSII and PSI, resulting in the blockage of electron transport and the inhibition of energy production (ATP and NADPH) and carbon capture (Zhang et al 2019b).…”