干旱对不同种植密度玉米生长发育及产量的影响

The Impact of Drought and Planting Density on Growth and Yield of Maize

【目的】确定干旱条件下玉米适宜的种植密度。【方法】在移动式防雨棚内设5个种植密度,分别为5.0万、5.5万、6.0万、6.5万和7.0万株/hm^2以及5个水分处理,即CK(全生育期土壤水分下限控制在田间持水率的75%±5%)、T1(拔节期,中度胁迫,土壤水分下限控制在田间持水率的50%±5%)、T2(拔节期,重度胁迫,土壤水分下限控制在田间持水率的40%±5%)、T3(灌浆期,中度胁迫,土壤水分下限控制在田间持水率的50%±5%)、T4(灌浆期,重度胁迫,土壤水分下限控制在田间持水率的40%±5%),研究了不同干旱程度对不同种植密度玉米生长发育及产量的影响。【结果】中度和重度干旱处理对玉米的生长发育和产量均有影响,拔节期中度水分胁迫对玉米的株高与干物质积累影响不大,对茎粗和叶面积指数有一定影响;灌浆期中度和重度的水分胁迫对玉米的形态指标及干物质积累均有显著影响。重度干旱对玉米的产量影响较大,较CK最大减产30.87%。水分正常或中度水分胁迫时,种植密度为6.5万株/hm^2的处理产量最高,重度水分胁迫时,种植密度为6.0万株/hm^2时产量最高。【结论】玉米植株种植密度过大或水分亏缺均会导致产量下降。因此,在较为干旱的地区,建议玉米种植密度为6.0万株/hm^2,适当降低玉米的种植密度,可减少产量损失。

[Objective] The overarching objective of this paper is to elicit the effects of drought on growth and yield of maize planted under different densities in attempts to experimentally find suitable planting density at dif- ferent drought level. [Method] The experiments were conducted in a mobile rainproof shelter, and the irrigations were determined based on real-time soil moisture measurements. We tested five planting densities： 50, 55, 60, 65 and 70 thousand/hm^2; and five irrigation treatments： keeping soil moisture at 75%±5% of the field capacity dur- ing the entire growth season （CK）, moderate water stress at the jointing stage by keeping the soil moisture at 50%±5% of the field capacity （T2）, moderate water stress at the gain-filling stage by keeping the soil moisture at 50%±5% of the field capacity （T3）, severe water stress at gain-filling stage by keeping the soil moisture at 40%± 5% of the field capacity （T4）. [Result] Both moderate and severe water stresses impacted the growth and ulti- mate yield of the maize. A moderate water stress at jointing stage did not have a noticeable effect on plant height and dry matter accumulation, but reduced the stem diameter and leaf area index. Moderate and severe water stresses at the grain-filling stage both significantly impacted the morphological index and dry matter accumulation, with severe water stress resulting a yield reduction by 30.87% compared to the CK. [Conclusion] The best planting density under normal irrigation or with moderate stress is 65 000 plants/hectare, while under severe water stress the density of 60 000 plants/hectare achieved the highest yield. Increasing planting density or water stress will reduce yield. In dry regions, therefore, decreasing planting density is a way to reduce yield loss.