水氮互作对河西走廊紫花苜蓿品质的影响

通过研究不同灌溉量(W₁:117 mm;W₂:156 mm;W₃:192 mm)和施氮量(N₁:0 kg·hm^-2;N₂:40 kg·hm^-2;N₃:80 kg·hm^-2;N₄:120 kg·hm^-2)互作条件下河西走廊紫花苜蓿水分利用效率、品质和相对饲用价值的变化特征,旨在确定紫花苜蓿品质最优时的水氮配置模式。结果表明,水氮互作显著影响了紫花苜蓿水分利用效率、粗蛋白质含量、中性洗涤纤维含量和相对饲用价值(P<0.05),但对紫花苜蓿地上生物量、粗脂肪、粗灰分含量和酸性洗涤纤维含量影响不显著。紫花苜蓿水分利用效率、粗蛋白质含量、中性洗涤纤维含量和相对饲用价值随灌溉量和施氮量的增加均呈开口向下的抛物线,最大值出现的组合分别为W₂N₃和W₂N₂,说明只有水氮合理配置才能提高紫花苜蓿品质和相对饲用价值。

Effects of irrigation and nitrogen fertilizer on alfalfa quality

The application of both nitrogen and irrigation have been shown to be beneficial to crop growth. A field experiment was carried out during 2015 in the Hexi Corridor to analyze the changeable characteristics of water use efficiency, quality and relatively feeding value of alfalfa under different irrigation regimes (W₁: 60% of conventional irrigation volumes; W₂: 80% of conventional irrigation; W₃: conventional irrigation) and nitrogen fertilizer levels (N₁: 0 kg·ha^-1; N₂: 40 kg·ha^-1; N₃: 80 kg·ha^-1; N₄: 120 kg·ha^-1). This study showed that the combination of different irrigation volumes and nitrogen fertilizer levels significantly affected the water use efficiency, crude protein content, neutral detergent fiber content and relatively feeding value of alfalfa but had no effect on aboveground biomass, crude fat content and crude ash content. Water use efficiency, crude protein content, neutral detergent fiber content and relatively feeding value of alfalfa all showed a downward trend (parabolic function) with increasing irrigation volumes and nitrogen fertilizer rate; the most beneficial combinations occurred in the W₂N₃, and W₂N₂ treatments which resulted in improved forage quality and relatively feeding value of alfalfa.