Influence of Drip Irrigation on Dry Matter Distribution and Yield Formation of the Grains of Densely Planted Maize

【Objective】 The purpose of this paper is to investigate the effect of drip irrigation amount on dry matter accumulation and distribution, as well as the yield formation of the grain machine harvest maize. 【Method】 The study was based on the drip irrigation experiment established in 2018 in the Experimental Field of Inner Mongolia Academy of Agricultural and Animal Husbandry Sciences. The experiment consisted of five irrigation treatments by irrigating 415 m3/hm2 (W1), 645 m3/hm2 (W2), 945 m3/hm2 (W3), 1 275 m3/hm2 (W4) and 1 605 m3/hm2 (W5), respectively. A rain-fed plot was taken as the control (CK). In each treatment, we measured the accumulation and distribution of above-ground dry matter in 2020 and 2021. Logistic model was used to describe the temporal change in dry matter accumulation, from which we further analyze the characteristics of dry matter accumulation and distribution, as well as the relationship of drip irrigation amount and yield under different treatments. 【Result】 Irrigation significantly increased the dry matter accumulation in the upper part of the plant; temporal change in the dry matter accumulation is well described by the logistic model, with R2>0.888. In 2020 and 2021, the maximum growth rate of the dry matter accumulation increased as the irrigation amount increased, with the increase in the CK being the least and the increase in W5 being the highest. The biological yield in W5 was the highest in both 2020 and 2021; the harvest index in W4 and W3 was the highest, being 0.51 and 0.50 respectively. Compared with CK, irrigation reduced dry matter distribution in the vegetative organs at maturity stage but increased dry matter accumulation in the grains. With the increase in irrigation amount, the economic yield in 2020 first increased, followed by a decline, maximizing in W4, reaching 14 282.42 kg/hm2 in 2021. The yield in W4 (15 480.33 kg/hm2) and W5 (15 892.52 kg/hm2) was significantly higher than that in other treatments. 【Conclusion】 Optimizing irrigation amount can significantly increase dry matter accumulation in the aboveground part, and promote distribution of dry matter in the grain. In drought years with average annual natural precipitation between 364.2 and 390.7 mm, the optimum drip irrigation amount is 1 275 m3/hm2 for grain machine harvest maize (planting density is 7.5×104 plants/hm2) in the arid and semi-arid areas in central and western Inner Mongolia.