甘肃荒漠灌区播量和行距对紫花苜蓿营养价值的影响

播量和行距是实现紫花苜蓿高产和优质的重要栽培技术措施。为此,采用裂区设计,以播量(12.0、16.0、20.0、24.0 kg·hm^-2)为主处理,3个等行距(10、15、20 cm)和2个不等行距(60 cm+40 cm间距、60 cm+30 cm间距,60 cm即种植6行,行距10 cm)为副处理,连续3年在甘肃荒漠灌区研究播量和行距对紫花苜蓿叶茎比和营养价值的影响。结果表明,播量和行距对叶茎比无显著影响,对营养价值有一定影响。其中粗蛋白、粗脂肪、钙和磷含量随播量、行距的增加呈先增加后降低趋势,3年平均粗蛋白含量在播量为16.0 kg·hm^-2,行距为20 cm时最高(20.06%),粗脂肪含量在播量为16.0 kg·hm^-2,行距为15 cm时最大(3.42%),钙含量在播量为20.0 kg·hm^-2,行距为20 cm时达到峰值(1.65%),磷含量在播量分别为12.0、16.0和20.0 kg·hm^-2,行距均为20 cm时最高(0.19%);中性、酸性洗涤纤维含量随播量增加呈降低趋势,随行距增加呈增加趋势,且中性洗涤纤维含量在播量为24.0 kg·hm^-2,行距为10 cm时最低(31.74%),酸性洗涤纤维含量在播量为24.0 kg·hm^-2,行距为15 cm时最小(25.64%);相对饲喂价值随播量的增加呈增大趋势,随行距的增加呈先升高后降低趋势,其值在播量为16.0 kg·hm^-2,行距为20 cm时最高(208.64%)。相同播量和行距下,紫花苜蓿营养价值受生长年限的影响。综合分析结果显示,播量为20.0 kg·hm^-2、行距为20 cm是该地区的最佳播量和行距,有利于提高紫花苜蓿的营养价值。

Effects of seeding rate and row spacing on nutritional value of alfalfa in the arid oasis region of Gansu Province

Seeding rate and row spacing are important cultivation details for alfalfa (Medicago sativa) need to be optimized to achieve high crop yield and forage quality. Therefore, an experiment to investigate the effect of seeding rate and row spacing on alfalfa performance was carried out in the arid oasis region of Gansu Province from 2014 to 2017. The experiment comprised four seeding rates (12.0, 16.0, 20.0 and 24.0 kg·ha^-1) arranged in a randomized complete block design with three replicates, and three equal row spacings (10, 15, 20 cm) and two wide-narrow row spacings (60 cm+40 cm, and 60 cm+30 cm) randomly arranged as split plot treatments within the main plots. In wide-narrow row spacings, groups of 6 rows with a narrow spacing of 10 cm were separated by a wider spacing of 30 cm or 40 cm. It was found that seeding rate and row spacing did not have any significant effect on leaf∶stem ratio, but significantly affected nutritional parameters of alfalfa forage. Across the range of seeding rates and row spacings, herbage ether extract, calcium, and phosphorus contents were highest at intermediate plant densities. Crude protein content was highest (20.06%) at the 16.0 kg·ha^-1 seeding rate and 20 cm row spacing combination, while the highest ether extract content (3.42%) was obtained at the 16.0 kg·ha^-1 seeding rate with 15 cm row spacing. Calcium content was maximized (1.65%) at the 20 kg·ha^-1 seeding rate and 20 cm row spacing, and phosphorus (P) content was maximized (0.19%) at the 3 lower seeding rates (12.0, 16.0 and 20.0 kg·ha^-1) and row spacing of 20 cm. The neutral detergent fiber (NDF) and acid detergent fiber (ADF) contents decreased with increasing seeding rates, while the NDF and ADF contents increased with increasing row spacings, and the lowest average NDF content (31.74%) was obtained at the 24.0 kg·ha^-1 seeding rate and 10 cm row spacing. The lowest ADF content (25.64%) was obtained at the 24.0 kg·ha^-1 seeding rate and 15 cm row spacing. The relative feed value (RFV) increased with increasing seeding rates and was highest at medium row spacings. Lastly, relative feed value was maximized (208.64%) at the 16.0 kg·ha^-1 seeding rate and 20 cm row spacing. The nutritional values of alfalfa herbage different between growing years at the same seeding rate and row spacing. It was indicated from comprehensive evaluation of the main nutrients, that the optimal planting configuration for improving alfalfa nutritional value in this climate was a seeding rate of 20.0 kg·ha^-1 and row spacing of 20 cm.