种植密度对不同株型玉米冠层光能截获和产量的影响

为了明确密植栽培中不同株型玉米的冠层光能截获、物质生产与产量的关系,以不同株型玉米陕单609 (紧凑型)、秦龙14 (中间型)和陕单8806 (平展型)为试验材料,设置4个种植密度(4.5×104、6.0×104、7.5×104和9.0×104株hm–2),于2016—2017年开展大田试验,研究密度对形态特性、冠层光分布、灌浆参数以及干物质积累等的影响。结果表明,陕单609、秦龙14和陕单8806两年平均产量依次为12,176、9624和8533 kg hm–2,分别在9.0×104、7.5×104和6.0×104株hm–2达到高产,产量较低密度分别提高了26.9%、20.4%和19.7%;随着种植密度的增加,叶面积降低,LAI和叶向值增加,在高密度下陕单609中间层由于较大的叶片和叶向值能截获更多的光能,秦龙14次之;灌浆速率达到最大时的天数(Dmax)、粒重(Wmax)、籽粒最大灌浆速率(Gmax)、平均灌浆速率(Gave)、籽粒活跃灌浆期(P)均随密度的增加而降低,高密度下陕单609的Dmax分别较秦龙14和陕单8806早1.4 d和3.0 d, Wmax和P分别高于秦龙14 (0.3g和3.3 d)和陕单8806 (1.1 g和5.4 d);吐丝后干物质积累量、干物质转运量及其对籽粒的贡献率随密度的增加呈先升高后降低的趋势。在高密度下,陕单609花后干物质积累量、花后干物质转运量和干物质转移对籽粒的贡献高于秦龙14 (5.1%、36.0%、33.5%)和陕单8806 (26.6%、46.7%、59.1%)。穗位层光能截获与产量(r=0.631)显著正相关(P0.05),与花后干物质积累量(r=0.661)和平均灌浆速率(r=0.859)极显著相关(P0.01)。可见,与秦龙14和陕单8806相比,紧凑型品种陕单609密植下调控穗上部叶片直立,改善冠层中下部光分布,维持较高的光合绿叶面积,延缓冠层叶片衰老,增加花后营养器官光合产物的积累以及籽粒灌浆速率,实现了增产。

Effect of planting density on light interception within canopy and grain yield of different plant types of maize

The objective of this study was to clarify the relationship between light interception in canopy and dry matter production and grain yield in different plant types of maize. The response of morphological characteristics, canopy light distribution, grain filling parameters and dry matter accumulation were studied using three different maize hybrids Shaandan 609 (SD609, compact), Qinlong 14 (QL14, semi-compact), and Shaandan 8806 (SD8806, flat) with four plant densities (4.5×10 ⁴, 6.0×10 ⁴, 7.5×10 ⁴, and 9.0×10 ⁴plants hm ^-2) in the field from 2016 to 2017. The average yields of SD609, QL14, and SD8806 were 12,176, 9624, and 8533 kg hm ^-2, respectively, within two years, reaching high yields under 9.0×10 ⁴, 7.5×10 ⁴, and 6×10 ⁴ plants hm ^-2, with the yield increase of 26.9%, 20.4%, and 19.7% compared with those under 4.5×10 ⁴ plants hm ^-2, respectively. With the increase of plant density, leaf area decreased, but LAI and leaf orientation value increased. The middle leaves of SD609 were more upright and larger than those of QL14 under 9×10 ⁴ plants hm ^-2. With increasing plant density, D_max (days to the maximum grain-filling rate), W_max (kernel weight at the maximum grain filling rate), G_max (maximum grain-filling rate), G_ave (average grain-filling rate) and P (active filling period) decreased, the D_max for SD609 was 1.4 days and 3.0 days earlier than that of QL14 and SD8806, and the W_max and P were higher than those of SD636 (0.3 g and 3.3 d) and SD8806 (1.1 g and 5.4 d), respectively. The dry matter accumulation after silking and the contribution of dry matter transportation to grain yield increased and then decreased with the increase of plant density, the accumulation, transportation and contribution to grain of dry matter after anthesis were higher in SD609 than QL14 (5.1%, 36.0%, 33.5%) and SD8806 (26.6%, 46.7%, 59.1%). The light interception in the ear canopy was significantly correlated with yield (r = 0.631, P < 0.05), the dry matter accumulation after silking (r = 0.661) and average grain filling rate (r = 0.859) at P < 0.01. Thus, compared with QL14 and SD8806, SD609 could regulate the mid and upper leaves more vertical under close planting, improve the light distribution in the mid and lower canopy, maintain a higher area of green leaves, delay the senescence of canopy leaves, increase dry matter accumulation after anthesis and grain filling rate, so obtain a higher grain yield.