Photosynthesis and Remobilization of Dry Matter in Wheat as Affected by Progressive Drought Stress at Stem Elongation Stage

Abstract

With increasingly erratic rainfall patterns particularly in drought-prone production systems, the capacity of plants to recover productively from drought spells becomes an important feature for yield stability in rainfed agriculture. Consequently, effects of water management at the stem elongation stage on partitioning and remobilization of dry matter, alteration in photosynthesis and water-use efficiency (WUE), and yield components of wheat plants were studied in a glasshouse pot experiment. The plants were subjected to three soil moisture regimes: well watered during all phenological stages (WW), drought affected during stem elongation and post-anthesis stages (DD) and drought affected during stem elongation and rewatered at post-anthesis stage (DW). Total dry weight substantially decreased by both drought treatments. However, DD plants allocated relatively higher assimilates to roots whereas DW plants remobilized them to the grains. Drought applications resulted in a decrease of grain yield and thousand grain weight while reduction was more pronounced in DD treatment. Relative contribution of post-anthesis photosynthesis to dry matter formation in grain was higher in WW treatment (72.6 %) than DD (68.5 %) and DW (68.2 %) treatments. Photosynthetic rate, gas exchange and transpiration decreased whereas leaf (photosynthetic) and plant level WUE increased with drought applications. However, all these parameters were rapidly and completely reversed by rewatering. Our findings showed that partitioning of dry weight to grain increases with rewatering of wheat plants subjected to drought during stem elongation phase, but the relative contributions of remobilization of stem reserves and postanthesis photosynthesis to grain did not change. Moreover, rewatering of plants at booting stage after a drought period lead to full recovery in photosynthesis and WUE, and a significant although partial recovery of yield components, such as grain yield, TGW and harvest index.

Maintenance of Photosynthesis as Leaves Age Improves Whole Plant Water Use Efficiency in an Australian Wheat Cultivar

“…Despite no genetic variation in WUE i (Figure 3), genotypic differences in WUE wp (2× higher in KR- Figure 1b) were consistent with previous studies in wheat and associated with maintenance of A as leaves aged [3][4][5]43,55]. Further, the 8% increase in WUE wp of KR between the GH experiment (harvested while reproductive), and the CE experiment (harvested while vegetative) indicates ontogenetic variation as evident in wheat and rice [4,56]. KR had higher WUE wp because it gained more biomass than GA despite similar water consumption.…”

“…However, wheat's projected production is expected to fall short of estimated consumption levels as the year 2050 approaches [2]. Further, wheat yield and whole plant water use efficiency (WUE wp ) are negatively impacted by water deficit conditions [3][4][5], which are becoming more prevalent in many wheat growing regions (e.g., The North China Plain) [6][7][8].…”

Effect of Drought Stress on Yield and Quality Traits of Common Wheat During Grain Filling Stage

“…Drought decreases plant water status, inhibits photosynthesis, induces oxidative water stress, restricts growth and finally lead to yield reduction in wheat (Wang et al, 2018). However, drought affects wheat growth in different ways depending on its timing, duration and intensity (Tatar et al, 2016). Rainless periods and water scarcity might be experienced during all growth stages of wheat but the effects of drought are more remarkable during post-anthesis and grain filling stages (Istipliler et al, 2017).…”

Effect of the transgenerational exposure to elevated CO2 on low temperature tolerance of winter wheat: Chloroplast ultrastructure and carbohydrate metabolism

“…Photosynthesis is the majority source of energy in plants, for which the structure of photosynthetic apparatus is very important (Brestic et al, 2018;Rapacz & Janowiak, 2008;Tatar, Brück, & Asch, 2016).…”