Responses of photosynthetic characteristics and antioxidative metabolism in winter wheat to post-anthesis shading

Abstract

In a field experiment, two winter wheat (Triticum aestivum L.) cultivars, Tainong 18 (a large-spike cultivar) and Jinan 17 (a multiple-spike cultivar), were treated with 78% (S1), 50% (S2), and 10% (S3) of full sunshine (S0, control) from anthesis to maturity to determine the responses of photosynthetic characteristics and antioxidative enzyme activities in a flag leaf. Compared with S0 treatment, the chlorophyll (Chl) content and maximal efficiency of photosystem II (PSII) photochemistry (F v /F m ) of flag leaves were enhanced in treatments S1 and S2. From 0 to 7 d post flowering, the Chl content and F v /F m in S3 were also higher than those in S0, but significantly lower than those in controls, respectively. With the increase of shading intensity, the effective quantum yield of PSII (Φ PSII ) was promoted; whereas, the ratio of Chl a/b declined. Compared with S0, treatments S2 and S3 significantly suppressed the activities of superoxide dismutase (SOD) and peroxidase (POD), net photosynthetic rate (P N ), and contents of total soluble sugar, nevertheless, S1 treatment showed positive effects on the above parameters. Under the same shading condition, Jinan 17 had larger Chl content and higher activities of PSII and antioxidative enzymes, but lower malondialdehyde (MDA) content than Tainong 18. The results indicated that multiple-spike cultivar was more advantageous for the Huang-Huai-Hai Plain, where shading problem occurs later during the growth period, than the large-spike cultivar, because of the lesser damage in a flag leaf and better photosynthetic function of the former one. Wheat plants under S1 shading condition had relatively high activities of antioxidative enzymes and a low degree of membrane lipid peroxidation, which was in favor of stress resistance, maintaining high P N duration, and accumulation of photosynthates in wheat plants.

Wheat and barley cultivars show plant traits acclimation and increase grain yield under simulated shade in Mediterranean conditions

“…Despite the reduction of the leaf N content, chlorophyll content (SPAD values) increased with shade in accordance with other shading studies on cereal crops (Li et al., 2010; Wang et al., 2015; Xu et al., 2013; Zheng et al., 2011). Shade‐adapted species typically have high leaf chlorophyll content compared with light plants, a trait that maximizes light capture (Valladares & Niinemets, 2008; Zhen & van Iersel, 2017) and commonly acclimation to shade results on greater leaf chlorophyll/Nitrogen ratio (Evans, 1996).…”

“…Xu et al. (2013) reported lower values of soluble sugars during the whole grain‐filling phase in the flag leaves of shaded plants (50% and 90% of shading) with respect to full‐sunlight plants in two wheat cultivars. However, low‐intensity shading plants (22% of shading) tended to accumulate more soluble sugar than control plants, especially in shade‐tolerant cultivars (Xu et al., 2013).…”

High Potassium Application Rate Increased Grain Yield of Shading-Stressed Winter Wheat by Improving Photosynthesis and Photosynthate Translocation

“…NS, no shading treatment; SE, shading from the 1st day to the 10th days after anthesis (shading at early filling stage for 10 days, SE); Five potassium rate, 0 (K0), 50 (K50), 100 (K100), 150 anthesis demonstrated an important link with the formation of spike grain number (Ferrante et al, 2010). Previous studies showed that the major reason for shading decreasing grain yield as reflected in the reduced TKW was due to depressed plant nitrogen accumulation, leaf photosynthetic rate and grain filling rate (Jia et al, 2011;Xu et al, 2013;Li et al, 2017). The reduction of grain weight had most serious impact on wheat yield (Mu et al, 2010), which was dependent on the number and size of endosperm cells.…”

“…The results demonstrated that shading reduced the nitrogen content of plant leaves (Pons and Pearcy, 1994) and the solar energy use efficiency of winter wheat leaf through depression of chlorophyll a/b and non photochemical quenching coefficient (NPQ) (Li et al, 2010). Moreover, the wheat leaf photosynthetic rate was also reduced by depressing the leaf temperature, stomatal conductance and transpiration rate under shading stress (Xu et al, 2013;Dong et al, 2019). Shading stress also resulted in changes to plant carbohydrate accumulation and distribution, causing carbon metabolism imbalance, and eventually led to yield reduction (Grashoff and d'Antuono, 1997;Mu et al, 2010).…”

Comparative studies on the photosynthetic characteristics of two maize (Zea mays L.) near-isogenic lines differing in their susceptibility to low light intensity

“…Most studies to date have used shading to investigate the effects of low intensity light on crop growth and development (Xu et al, 2013;Cui et al, 2015). Many studies have shown that shade treatment not only reduces the intensity of light but also increases the diffuse light proportion (Gu et al, 2002;Greenwald et al, 2006) and changes the light spectral quality (Bell et al, 2000).…”