石羊河流域春秋不同播期人工牧草气候生产力分析

Climate-productivity analysis of artificial grass in different sowing time in arid area of Shiyang River basin

2003～2005年对石羊河流域春秋两种播期人工牧草紫花苜蓿(Medicago sative)、沙打旺(Astragalus adsurgens)的生育期,地上、地下生物量,产量等进行了连续测定。结果表明:(1)紫花苜蓿、沙打旺生长第二年(2004年)干物重春播地均高于秋播地。分别增产3 505.0 kg/hm2、2 314.5 kg/hm2。(2)春播和秋播地牧草干物质积累增长关键期均出现在现蕾～开花期。此期紫花苜蓿、沙打旺干物质积累量分别占累积总量的70%和63%。(3)生长第二年(2004年)春播和秋播地青干比最小值出现在开花期,也是牧草刈割的最佳期。(4)春播牧草地下生物量高于秋播。春播紫花苜蓿、沙打旺根干重分别比秋播高2.5～2.6倍和0.5～1.0倍,春播有利于牧草根系生长。(5)春季日平均气温稳定通过5℃为牧草适宜返青温度。在灌溉条件下,牧草干重与热量因子呈显著正相关,生产力高低主要取决于热量的多寡,秋播地和晚熟品种对热量条件的需求更高。

In order to reduce the pressure of water resources in the basin, adjustment and optimized agriculture planting structure, development grass livestock industry, after two years＇sowing seeds by stages experiment, growth and development characteristics, yield forming laws and adaptability to climate of the two kinds of grass, Medicago satire and Astragalus adsurgens under the condition of artificial planting were determined. The result indicated; （1） The dry matter weight of Medicago satire and Astragalus adsurgens of the second year（2004） in the spring sowing land was higher than in the autumn sowing land, increasing the yield by 3 505.0 kg and 2 314.5 kg per hm^2 respectively. （2） The increase of grass dry weight and plant height sowed in spring and in autumn was basically isochronous and the growth key time all appeared in budding and flowering period. In this period, dry matter accumulation quantity of Medicago satire and Astragalus adsurgens was respectively 70 % and 63 % of the total. （3） The least value, which was showed by the ratio between dryness and blueness of two kinds of grass growing on the second year （2004） in spring sowing land and autumn sowing land, appeared in flowering period which was also the best time to reap pasture. （4） The grass underground biomass in spring sowing land was better than in autumn sowing land. The grass in spring sowing land was helpful for root system to grow. （5） It was the fitting temperature for pasture to return green that means daily temperature steadily passed 5℃ in spring. Under the condition of irrigation, pasture dry weight was positively associated with heat factor and the productivity was mainly dependent on heat and the requirement of autumn sowing land and late maturing variety for heat condition was more urgent.