西北干旱区旱地玉米叶面积指数与气象因子及生物量的关系

Relationship among LAI and Meteorological Factors and Biomass of Maize in Dry-farming Areas of Northwestern China

利用甘肃省西峰农业气象试验站1994—2008年玉米试验观测资料,对玉米的LAI变化规律,温度、光合有效辐射对LAI的影响,LAI对50 cm土层土壤贮水量、生物量及产量因子的影响进行了分析。结果表明,三叶期—乳熟期LAI随着出苗后的天数呈S曲线变化。缓慢增长期出现在8～28 d;快速增长期出现在28～74 d;缓慢下降期出现在74～103 d。叶片含水率以0.9%/10 d的速度线性下降。各试验年份间,降水差异较大,变异系数为31%～92%;其次为≥10℃有效积温;光合有效辐射比较稳定。从播种到乳熟期,各年份的气象要素值趋于平均值。LAI与≥10℃有效积温及光合有效辐射呈幂函数变化,有效积温500℃及光合有效辐射值250 MJ/m2是LAI累积速度变化的转折点。≥10℃有效积温500～1 000℃及光合有效辐射800～1 000 MJ/m2是LAI快速增长的阶段。随着LAI的增大,50 cm土层贮水量呈线性减少。LAI对生物量的影响可用幂函数描述,最利于生物量累积的LAI值为3.5,较为适宜的种植密度为60 000株/hm2。七叶期—拔节期阶段LAI与产量因子的相关性较差,抽雄期—乳熟期阶段LAI与产量因子的相关性显著。在一定范围内,抽雄期LAI的增大对提高玉米的经济产量有利。

Based on the experiment data of maize on the Xifeng Agrometeorological Experiment Station and meteorological data on Xifeng National Base Climate Station from 1994 to 2008,the characteristics of LAI（Leaf Area Index） and influence of accumulated temperature and PAR（Photosynthetically Active Radiation） on LAI,influence of LAI on total water storage in depth of 50 cm in soil,biomass and yield factors have been analyzed.The results showed that the LAI in three leaves period to milky mature period presented ＂S-shape＂ curves with the days in which LAI increased slowly in 8 to 28 days after emerging then increased rapidly at a rate of 0.7/10 days in 28 to 74 days after emergence and at last decreased slowly at a rate of 0.1/10 days in 74 to 103 days after emerging and water ratio of leaves decreased by 0.9% every 10 days.During the experiment years,the different values of precipitation was bigger which the variation coefficients were 31% to 92%;next was effective accumulated temperature ≥10 ℃ with the variation coefficients 15% to 58% and PAR was the stable factor in which the variation coefficients were 6% to 18%.The meteorological factors in all experiment years tended to be average value from sowing to milky maturation period.LAI and effective accumulated temperature and PAR varied with power function that turning point of values of LAI were in 500 ℃ of effective accumulated temperature and 250 MJ/m2 of PAR.Total water storage in depth of 50cm in soil decreased by 11 mm with LAI increased by 1.Biomass of maize turned to be power function described by LAI in which the most optimum value is 3.5.The most optimum planting density was 60000 plants per hectare.Relevance between yield factors and LAI in seven leaves to jointing period was not notability but notability in tasseling to milky maturation period.LAI in tasseling period within the specific limits was favorable to improve economic outputs.