Efficacy of planting date adjustment as a cultivation strategy to cope with drought stress and increase rainfed maize yield and water-use efficiency

Given the frequent drought pressure caused by the unpredictable and limited precipitation concurrent with global climate change, highly efficient cultivation technologies have been increasingly recognized by various levels of scientific communities. Understanding plant–environment relationships in rainfed dry land may help maximize crop productivity while improving water utilization of farmland. Field experiments were conducted in 2012–2014 at the Dryland Maize Experimental Station of the Northwest A&F University, China to determine the effects of possible drought stress and the environmental factors involved during sowing at different sowing dates on maize vegetative growth and grain yield (Zea mays L.), as well as water-use efficiency (WUE=grain yield per unit of seasonal evapotranspiration). Six planting date (PD) treatments with sowing performed for 6 days from April 10 to May 10 were designed. Results showed that the maize growth period was shortened with the postponement of planting time. The vegetative growth stage and the overlapping stages of vegetative and reproductive growth varied by 4–19 days among various PD practices. However, the reproductive growth stage duration was relatively stable and varied by 3–5 days only among the different PD practices. Within a certain time range, dry matter production per plant did not obviously change across the different PD treatments. However, the dry matter accumulation in the ear after flowering, the yield, and the WUE in the treatments under appropriate PDs (April 16–April 28) were 2.2%–28.8%, 2.3%–24.7%, and 6.6%–15.2% higher, respectively, than those in the early or delayed PDs. These findings resulted from the changes in soil water content with PD adjustment. Yield was highly correlated to the soil moisture content during PD, the rainfall before silking, the effective accumulated temperature after silking, and the sunshine hours after silking. Moreover, the thousand-grain weight was highly correlated with the sunshine hours after silking. In the early PDs, the main factor that affected maize yield was the low content of soil moisture, which generated low effective ear number per unit area and seedling emergence ratio. In the late PDs, the main factors that influenced maize yield were the low effective accumulated temperature and the short sunshine hours during the reproductive growth stage, which produced less dry matter accumulation after silking and lower thousand-grain weight. Under suitable sowing time, the actual harvest ear number per hectare and dry matter accumulation of female ear after silking increased. Similarly, the maize yield and WUE increased. By considering the ecological factors and study results, we recommend that the most suitable sowing time for maize should be determined on the basis of the soil moisture content before April 28. As such, we can effectively achieve high yield and avoid drought in the study region. Overall, the results can provide effective cultivation techniques to prevent drought stress in spring maize in the present agro-ecosystem of northern China and other similar areas.