Effects of continuous versus pulsed drought stress on physiology and growth of wheat

Abstract

In the course of climate change, crop plants are exposed to both altered precipitation volumes and frequencies in many cultivation areas. Reduced water availability and longer periods without precipitation can lead to changes in plant physiology and productivity. In this greenhouse study, we investigated physiological responses, including maximum quantum yield of photosystem II (F /F ) and water use efficiency (WUE) as well as diverse productivity-related parameters, including grain yield per plant, to continuous (irrigated three times a week) versus pulsed (once a week) irrigation in spring wheat (Triticum aestivum L.). In both drought regimes, plants were exposed to four different irrigation volumes. F /F was not influenced by irrigation treatment but was significantly higher after 6 weeks of drought than after 2 weeks. WUE increased with decreasing irrigation volume and based on generative biomass; it was higher in continuously-watered compared to pulsed-watered plants that received a similar amount of water over the experiment. Infrequent irrigation led to a reduction in grain yield of up to 51%. This lower productivity was primarily caused by fewer tillers in pulsed-watered plants. Additionally, at low water volume the thousand grain weight (TGW) was lower in infrequently-compared to frequently-watered plants. In contrast, the number of grains per ear was higher in pulsed-watered plants. In conclusion, reduced irrigation frequency, next to a decrease in irrigation volume, negatively affects WUE and grain yield of spring wheat. These results might have important implications for irrigation scheduling and breeding programmes under a changing climate.

Wheat growth, applied water use efficiency and flag leaf metabolome under continuous and pulsed deficit irrigation

“…This finding could be due to higher evaporation from soil after pulse irrigation and/or differences in root systems between cd and pd plants. In a previous experiment in which wheat plants of the same cultivar were differently irrigated and harvested after fruit ripening, the WUE apl based on the grain yield, but not that based on the vegetative biomass, was higher in cd than in pd plants 47 . Both studies highlight that the investment of wheat plants into vegetative and generative growth under drought depends on the irrigation frequency and the improvement of the WUE apl and that the harvest index is limited at low irrigation frequencies.…”

“…Six days after sowing, five seedlings were planted together in an equal distance of 6 cm surrounding a central seedling in each of 60 pots (4 L, 15.7 × 15.7 × 23.3 cm; Meyer, Rellingen, Germany) to simulate natural competition. Each pot contained 4,185 g of the substrate mentioned above, with a substrate water content of 23% (determined gravimetrically in a previous experiment 47 ). Pots had holes at the bases to allow draining and were placed on dishes to prevent water loss after leaching.…”

Effective Water Use Required for Improving Crop Growth Rather Than Transpiration Efficiency

“… Tanner and Sinclair (1983) proposed that VPD is equal to 0.75 of the difference between maximum daily vapor pressure and minimum daily vapor pressure. Abbate et al (2004) subsequently concluded that the weighting coefficient in the calculation of VPD for Argentine environments was 0.72.…”

Identification of Two Novel Wheat Drought Tolerance-Related Proteins by Comparative Proteomic Analysis Combined with Virus-Induced Gene Silencing

“…The physiological changes of wheat plants under drought stress, and the molecular mechanisms underpinning the response to drought stress have been well studied [6,7,8,9]. Relative water content (RWC), relative conductivity, malonaldehyde (MDA), and proline content are important physiological indicators that reflect plant drought tolerance.…”