不同播种方式下苜蓿与无芒雀麦人工草地的小气候特征分析

Analysis of Microclimate Characteristics of Man-made Alfalfa and Smooth Brome Grass Grassland under Different Sowing Patterns

为指导北方地区人工草地的建植和调控,以不同播种方式的2a生人工草地的头茬草为试验对象,采用田间测定小气候要素的方法,研究了紫花苜蓿(Medicago sativaL.cv.A lgonquin)与无芒雀麦(Bromus innerm isLeyss cv.Carlton)在同行混播(TH)、间行混播(JH)和单播(单播紫花苜蓿DM,单播无芒雀麦DW)方式下草地群体的小气候特征。结果表明,在紫花苜蓿处于初花期、无芒雀麦处于孕穗期时,群体内部光照强度和风速均为:单播无芒雀麦>同行混播、间行混播>单播紫花苜蓿;温度:单播无芒雀麦>单播紫花苜蓿>同行混播、间行混播;相对湿度:同行混播、间行混播>单播紫花苜蓿>单播无芒雀麦;浅层地温为单播无芒雀麦明显偏高,其余差异不大。株高是影响田间小气候的关键因素,不同播种方式下平均株高与0cm、20cm和40cm处平均光照强度均呈极显著的负相关(r0 cm=-0.973,r20 cm=-0.994,r40 cm=-0.973,r0.01=0.959),与30cm和60cm处平均风速负相关也达到极显著水平(r30 cm=-0.959,r60 cm=-0.973)。单播无芒雀麦由于氮素养分缺乏而植株矮小,群体光截获少,光能利用率低;单播紫花苜蓿群体光截获量最大,基部光照已处于光补偿点,下部叶片净光合速率开始下降;同行混播和间行混播群体下部光照强度适宜,群体保持较高的光合速率,并最终形成了较高的草产量。

Based on the two-year man-made grassland experiments with alfalfa （Medicago sativa L. cv. Algonquin） and smooth brome grass （Bromus innermis Leyss cv. Carlton） under the different sowing patterns, which were with four treatments, namely one-line mixed sowing of alfalfa and smooth brome grass （TH）, inter-line mixed sowing of alfalfa and brome grass （JH） , mono-sowing of alfalfa （DM） and mono-sowing smooth brome grass （DW） , the mieroclimate characteristics was studied. The results showed that both light intensity and wind speed were the highest in the DW treatment and the lowest in the DM treatment, while they were in between in the TH and JH treatments as the alfalfa was in initial bloom stage and smooth brome grass was in booting stage. The temperature was higher in the monosowing than that in the mixed sowing, while the relative humidity was higher in the mixed sowing than that in the mono-sowing. The average plant heights under the different sowing patterns were significantly negatively related with the average light intensity at 0 cm, 20 cm and 40 cm above the ground with r0cm = - 0. 973, r2cm = - 0. 994 and r40cm = -0. 973 respectively, and with average wind speed at 30 cm and 60 cm above the ground with r30cm = -0. 959 and r60cm = -0. 973 respectively. The light intercepted by the population of DM was the largest, but its bottom light cameto light compensation point and leaves net photosynthetic rate in the bottom began to decrease. The bottom light intensity of TH and JH were appropriate, so the populations kept photosynthetic rate high and got relative higher biomass.