干旱半干旱地区紫花苜蓿营养品质对水分胁迫的响应

随着用水总量的严格控制,干旱半干旱缺水地区紫花苜蓿(Medicago sativa)品质对水分的响应研究极为重要。在充分灌溉(4 200m~3·hm~(-2))、充分灌溉量的80%(3 360m~3·hm~(-2))和充分灌溉量的60%(2 520m~3·hm~(-2))条件下,测定苜蓿茎叶比和营养品质指标,研究水分胁迫与苜蓿营养品质间的关系,明确苜蓿营养品质对水分胁迫的响应。结果表明,整个生长期,苜蓿产草量(茎重+叶重)、粗蛋白含量、粗脂肪、粗灰分含量基本遵循第1茬第2茬第3茬,酸性洗涤纤维、中性洗涤纤维含量与之相反;充分灌溉量的80%与充分灌溉和充分灌溉量的60%相比,产草量分别增加5.10%和10.60%,粗蛋白含量平均增加9.60%、22.74%,粗脂肪含量平均增加3.33%、7.90%,酸性洗涤纤维平均降低8.57%、13.30%,中性洗涤纤维平均降低6.51%、11.56%,粗灰分含量平均增加3.20%、4.54%,因此灌水量为充分灌溉量的80%灌溉有利于提高干旱半干旱地区水资源利用效率和苜蓿的营养品质。

Effects of water stress on nutritional quality of alfalfa in arid and semiarid areas

This study examined the effects of water stress on nutritional quality of alfalfa in arid and semiarid areas,which are under strict controls of water consumption.We conducted a field experiment considering alfalfa under full irrigation conditions (4 200 m3·hm-2),80% full irrigation (3 360 m3·hm-2),and 60% full irrigation (2 520 m3·hm-2),and measured the stem-leaf ratio and nutritional quality index.We found that throughout the growing season,there were significant differences in the distribution of crude protein,ether extract and crude ash among different cuttings.The size of these differences declined from the first cutting to the third cutting.In leaf-stem ratio,neutral detergent fiber content,and acid detergent fiber content,this trend was reversed.Further analysis showed that in comparison with full irrigation,yield from plants irrigated at 80% increased by 5.10%,and in comparison with 60% full irrigation,yield from plants raised under 80% irrigation increased by 10.60%.Under the same comparisons,crude protein content rose 9.60% and 22.74%,ether extract content rose 3.33% and 7.90%,acid detergent fiber content fell 8.57% and 13.30%,content of neutral detergent fiber fell 6.51% and 11.56%,and crude ash content rose 3.20% and 4.54%.We conclude that 80% full irrigation during the growing season is an optimum level for improving water use efficiency and nutritional quality of alfalfa in arid and semiarid areas.