Does cyclic water stress damage wheat yield more than a single stress?

Abstract

The occurrence of water stress during wheat growth is more frequent due to climate change. Three experiments (cyclic drought, cyclic waterlogging, and cyclic drought plus waterlogging) were conducted to investigate the effects of mild and severe cyclic/single water stress at elongation and heading stages on winter wheat (Triticum aestivum L.) yield. The effect of either mild drought at elongation or mild waterlogging at heading on wheat yield was not significant; however, significance did occur under other single water stresses. As the stress becomes more severe, the yield loss significantly increases. Extreme drought/waterlogging treatment at elongation caused a greater yield penalty than stress at heading stage. Except the combination of mild drought and mild waterlogging treatment, cyclic water stress significantly decreased wheat yields. The decrease in wheat yield under cyclic severe drought and waterlogging was significantly higher than any other treatment, with percentage decreases of 71.52 and 73.51%, respectively. In general, a yield reduction from mild cyclic water stress did not indicate more severe damage than single treatments; in contrast, grain yield suffered more when water stress occurred again after severe drought and waterlogging. Drought during elongation significantly decreased kernel number, whereas drought at heading/waterlogging during elongation and heading decreased the spike weight, which might be the main reason for the yield penalty. Furthermore, water stress caused variation in the decrease of total biomass and/or harvest index. The present study indicates comprehensive understanding of the types, degree, and stages of water stress are essential for assessing the impact of multiple water stresses on wheat yield.

A Physio-Morphological Trait-Based Approach for Breeding Drought Tolerant Wheat

“…In general, while the intensity and frequency of drought are extremely critical to the overall performance of the crop, the phenological stage at which drought events occur is equally important (Sarto et al, 2017). Wheat plants may be more susceptible to drought at specific critical growth stages, i.e., germination and seedling stages (Akram, 2011); tillering and stem elongation stages Wang et al, 2015;Ding et al, 2018); and heading, anthesis and grain filling stages (Akram, 2011;Sarto et al, 2017). The morphological traits that contribute to final grain yield differ at each growth stage, and the extent to which these are impacted by drought, determine the seriousness of the stress event (Figure 3).…”

“…It is important to note that in the literature (e.g., Table 1), the severity of drought (mild or severe) that is reported can be subjective, dependent on the authors of a particular study. For example, Ding et al (2018) defined treatments with 75, 60, and 40% soil moisture content as control, mild drought and severe drought, respectively, while other studies have used different thresholds ( Table 1). It may be more useful to define drought severity objectively, based on the quantitative frequency and FIGURE 3 | The figure shows different growth stages of wheat along with the associated visible growth events and traits related to drought tolerance.…”

The Effects of Flood, Drought, and Flood Followed by Drought on Yield in Cotton

“…PRY infers the yield loss ratio of a crop that is caused by a unit of a certain stress index. 1 'DR1' and 'DR2' represent 10-day and 15-day drought, respectively; 'FL1' and 'FL2' represent five-day and eight-day flood, respectively. 'FL1-DR1' represents a five-day flood followed by a 10-day drought.…”

“…To eliminate the negative impacts of drought (referring to agricultural drought in this study) and flood stresses on crops, it is essential to develop appropriate irrigation and drainage schedules. However, in the context of global climate change, droughts and flood occur more frequently and severely; they also alternate, which poses new threats to agricultural production [1][2][3][4]. Thus, it is speculated that traditional schedules of irrigation and drainage could be improved by accounting for the particular responses of crop yields under alternating drought and flood stresses.…”

Influence of soil moisture levels on the growth and reproductive behaviour of Avena fatua and Avena ludoviciana

“…A considerable reduction in A. fatua and A. ludoviciana growth and seed production was observed at 60% WHC as compared with 100% WHC. Since the main winter crops, such as wheat, require >60% WHC to avoid yield reduction, growers implement favourable soil moisture regimes throughout the growing season in irrigated wheat and barley crops [50]. In such situations, if A. fatua and A. ludoviciana plants are not controlled, eventually they will optimally grow, reproduce, and interfere with crops due to the available soil moisture.…”