Physiological and Morphological Basis of Improved Water‐Use‐Efficiency in Wheat from Partial Root‐Zone Drying

Abstract

Water‐saving breeding and cultivation of winter wheat (Triticum aestivum L.) have always been among the important missions in North China. But there is still a dispute on the regulation of water use in winter wheat. A pot experiment was conducted to investigate the physiological and morphological mechanisms of water use in two cultivars of winter wheat (KN9204 and drought‐tolerant LH2) via partial root‐zone drying (PRD). The results indicated that the weight of 1000 grains was higher under PRD conditions for both cultivars. Total water consumption per plant significantly decreased by 11.6 and 17.3% for KN9204 and LH2, respectively, and water‐use efficiency (WUE) significantly increased by 17.2 and 20.3% under PRD. The net photosynthetic rate did not differ between PRD and full irrigation (FI) for either cultivar; however, transpiration rate was lower under PRD than FI, which improved WUE at the leaf level. Flag leaf water potential was significantly lower under PRD than FI for both cultivars, while water content was similar for both treatments. The soluble sugars content of leaves of KN9204 was higher under PRD than FI, while the proline content was 45.9% (KN9204) and 15% (LH2) higher under PRD. Stomatal density increased under PRD, but stomatal width and area declined. Overall, the two types of winter wheat had both common and individual means of improving WUE under PRD conditions. The results would further improve the theoretical underpinning of water‐saving breeding and cultivation in winter wheat.

Physiological mechanisms contributing to increased water-use efficiency in winter wheat under organic fertilization

“…To improve the capacity of plants for water capture, RWt was higher under WS than WW, and resulted in greater R/S than WW as reported previously [ 31 ]. WS stimulated plants to allocate a greater proportion of photosynthate to the ears through enhancing DMR and DMRE, in agreement with previous studies [ 4 , 41 – 44 ]. However, under M treatment, an increase in post-anthesis DM accumulation allowed a lower use of pre-anthesis DM reserves, consistent with previous study [ 44 ].…”

“…Finally, the flag leaves were dried to measure dry weight (DWt). Leaf relative water content (LRWC), excised-leaf water loss rate (EWLR) and water retention capacity (WRC) were calculated as following [ 4 , 23 ]: …”

“…To achieve higher crop yield, the application of synthetic N fertilizers has markedly increased in recent years [ 3 ]. The increasing use of inorganic fertilizer and neglect of organic fertilizer as a valuable source of nutrients have contributed to nutrient imbalance, low fertilizer use efficiency [ 4 ], deterioration in soil quality [ 5 – 7 ], nitrate leaching, and nitrous oxide emissions, soil acidification [ 8 ] and carbon (C) loss [ 9 ], which seriously limit crop productivity. Therefore, the effective use of limited water resources and chemical fertilizer to achieve high yield is a major objective of modern agriculture in the Loess Plateau, and will have a considerable impact at local and regional scales.…”

“…Generally, to our knowledge, there is no uniform view on the physiological mechanism by which winter wheat regulates WUE. Some studies have reported that increased plant drought tolerance and decreased leaf water loss, which can reduce damage to plants and enable them to maintain higher net photosynthetic rate (P n ), play an important role in improving WUE [ 4 , 16 ]. There are some reports that root pruning increases yield and WUE by maintaining a higher P n and reducing transpiration (T r ) and stomatal conductance (g s ) [ 17 , 18 ].…”

Determining the best drought tolerance indices using Artificial Neural Network (ANN): Insight into application of intelligent agriculture in agronomy and plant breeding

“…Also, a large variation explained by environments (28.65% of the total sum of square) revealed that environments were diverse with large differences among environmental means causing most of the variation in grain yield. Grain yield is a complex quantitative trait, which is controlled by multiple genes and is highly influenced by various environmental factors (Shi et al 2014). Hence, the detected different responses to drought stress in this study may be resulted from genetic variability among genotypes or environmental conditions and even presence of the interaction among genotypes and environments.…”