Abstract:

To improve alfalfa (Medicago sativa L) nutritional quality and explore the dynamics law and mechanism of nutrient accumulation and distribution at different growth stages, the impacts of basal selenium fertilizer on alfalfa nutritional content and distribution were studied by a field experiment. The results showed that selenium application as basal fertilizer increased the crude protein, crude fat, crude ash, phosphorus and potassium contents of alfalfa, whereas decreased NDF, ADF contents of alfalfa. Alfalfa had the best nutritional quality when the basal amount of selenium fertilizer was 0.45 kg·hm^-2. The crude protein, crude ash and phosphorus contents of alfalfa were the highest at the shooting stage and the lowest at the early flowering stage, while the crude fat content was the highest at the early flowering stage and the lowest at the seedling stage. The maximum NDF content of alfalfa was at the budding stage, the maximum ADF and potassium contents were at the open flowering stage, whereas the minimum NDF, ADF and potassium contents were at the seedling stage. The leaf crude protein, crude fat, crude ash, phosphorus, potassium contribution rates of alfalfa were more than 50%, while the leaf NDF, ADF contribution rates were less than 50%. The appropriate selenium application as basal fertilizer significantly increased the leaf crude fat (P<0.05), leaf phosphorus, leaf potassium contribution rate and leaf crude protein, NDF contribution rate of alfalfa at the budding stage. Leaf ADF contribution rate at the seedling stage and leaf crude ash contribution rate at the shooting stage were the biggest when the amount of basal selenium was 0.45 kg·hm^-2. Therefore, the leaf of alfalfa was an important source of nutrition, adequate selenium-based fertilizer could improve the nutritional quality and raise alfalfa leaf nutritional contribution rate. The relatively high nutritional period of alfalfa was at the branching stage, and the effective amount of selenium fertilizer was 0.45 kg·hm^-2.

Key words: Selenium (Se), Alfalfa (Medicago saliva L.), Growth period, Nutritional content

摘要：

为改良紫花苜蓿（Medicago salivaL.）营养品质，探索不同生育期营养积累分配的动态规律，通过田间试验研究不同基施硒肥用量对其不同生育期营养含量及分配的影响。结果表明：适量基施硒肥能提高紫花苜蓿粗蛋白、粗脂肪、粗灰分、磷和钾的含量，降低中性洗涤纤维（NDF）和酸性洗涤纤维（ADF）的含量；以基施硒量0.45kg·hm^-2效果最好，营养品质最佳。紫花苜蓿粗蛋白、粗灰分和磷含量分枝期最高，初花期最低；而NDF含量孕蕾期最大，ADF和钾含量盛花期最大，钾、NDF和ADF含量苗期最小；粗脂肪含量初花期最高，苗期最低；叶粗蛋白、粗脂肪、粗灰分、磷、钾的贡献率均高于50%，而叶NDF和ADF贡献率低于50%。适量基施硒肥能显著提高各生育期叶粗脂肪、叶磷、叶钾贡献率及孕蕾期叶粗蛋白、NDF贡献率（P<0.05），苗期叶ADF贡献率和分枝期叶粗灰分贡献率，以基施硒肥0.45kg·hm^-2时达到最大。综上可知，叶是苜蓿营养的重要来源，适量基施硒肥能改善苜蓿营养品质并提高叶营养贡献率；分枝期是苜蓿营养相对较高的生育期，以基施硒肥0.45kg·hm^-2效果最好。

关键词: 硒, 紫花苜蓿, 生育期, 营养含量