Changes in Radiation in Canopy and the Yield of Maize in Response to Planting Density and Irrigation amounts

Abstract

【Objective】 Planting density and soil moisture combine to modulate plant growth and its ultimate yield. Taking maize as an example, this paper investigates the response of light radiation in the canopy and yield of the maize to different combinations of plant density and irrigation amounts. 【Method】 Maize variety Xianyu 335 was used as the model plant, and we compared two planting densities: 70 000 plants/hm2 (D1) and 90000 plants/hm2 (D2). Added to each planting density were three irrigation treatments: Sufficient irrigation (W1), mild (W2), and moderate (W3) deficit irrigation. In each treatment, we measured the changes in leaf area index, chlorophyll content, radiation interception rate, dry biomass accumulation at different growth stages and the final maize yield. 【Result】 Chlorophyll content was significantly affected by soil water but not by planting density, and it hence increased with irrigation amount. LAI was higher in D2 than in D1 at significant level, indicating that increasing planting density boosted radiation interception thereby improving light energy utilization and dry matter accumulation. Reducing irrigation amount in both planting densities led to a decline in yield, though the reduction in D2 was less than that in D1. Under sufficient irrigation, increasing planting density from D1 to D2 increased the yield from 3.39 t/hm2 to 16.39 t/hm2. Imposing mild or moderate deficit irrigation reduced the yield of D1 by 2.63% or 7.03%, and the yield of D2 by 22.76% or 22.84% respectively. Water use efficiency of both planting densities was contingent on irrigation, ranked in the order of W2>W3>W1. The harvest index varied with planting density and irrigation amount. Mild deficit irrigation in D1 gave the highest harvest index, while moderate irrigation in D2 worked better. 【Conclusion】 A moderate increase in planting density of maize can benefit photosynthesis and increase dry matter accumulation, thereby improving both yield and water use efficiency. Combining with moderate deficit irrigation can further improve water use efficiency without compromising yield.

Keywords

• planting density
• water deficit irrigation
• canopy light interception
• yield
• maize