灌溉条件下不同生长年限紫花苜蓿生长及生产能力的研究

Study on the growth and productivity of alfalfa with different growth years under irrigation condition

2007年4-10月在地处西辽河平原的内蒙古民族大学实验农场,对5个不同生长年限紫花苜蓿Medicago sativa生产能力进行了研究,结果表明:紫花苜蓿净光合速率总体上表现为生长2年较高、生长6年较低,但刈割茬次间有所不同。紫花苜蓿叶绿素a、叶绿素b的含量在第1茬中表现为随生长年限的增加而降低,而在第2、第3、第4茬中均以生长3年、生长4年含量较高,生长2年、生长6年含量较低。类胡萝卜素的含量在第1茬中随生长年限的增加而降低,其余各茬含量与生长年限的规律不明显。紫花苜蓿全年草产量生长2年>生长3年>生长4年>生长6年>生长1年。不同生长年限紫花苜蓿植株密度随生长年限的增加而降低,根腐率、根颈粗、颈蘖数均随生长年限的增加而增加。0～50cm土层内紫花苜蓿主根干质量和侧根数均以生长3年最高,而侧根干质量则以生长4年最大。

The study on the productivity of five different growth years of Medicago sativa was carried on the experimental farm of the Inner Mongolia University for Nationalities in Xiliaohe Plain from April to October in 2007. The results showed that the net photosynthetic rate of two-year old alfalfa was higher but lower for six-year old alfalfa in generally, and varied among cutting times. With the increase of the growing year, the content of chlorophyll a and chlorophyll b decreased in first cutting, but the content of three-year old and four-year old alfalfa were higher in the second, third and fourth cuttings, and the two-year old and six-year old alfalfa were lower. The content of Carotinoid decreased in the first cutting with the increase of the growing year, but there was no obvious correlation between the content of Carotinoid and growing years in the other cuttings. The whole year alfalfa yield ranked as： two-year〉three-year〉four-year〉six-year〉one-year. With the increase of growing year, the plant density of alfalfa with different growth years decreased, but the rate of rotted roots, the root crown diameter and the tiller number of root crown increased. The dry weight of major root and the number of lateral root of three-year old alfalfa were the highest, and the dry weight of lateral root of four-year old alfalfa was the highest in 0--50 cm soil layer.