Abstract:

The influences of selenium in soil on the selenium absorption and conversion of organic selenium and selenium fertilizer use efficiency of alfalfa at different growth stages were investigated by a field experiment. The results showed that the basal application of Se fertilizer could significantly improve the alfalfa absorption of Se (P<0.05). The ability of alfalfa absorbing Se reached the highest peak at the initial bloom stage. The Se content of alfalfa decreased as the development of alfalfa growth stage. Se fertilizer application significantly increased the conversion of alfalfa organic Se (P<0.05), the conversion rate of alfalfa organic Se was more than 50% after applying 0.45 kg Se·hm^-2 or more, and decreased as the development of the alfalfa growth stage. The utilization rates of Se fertilizer increased first and then decreased during the whole growth period. The highest utilization rate of Se fertilizer was at the initial bloom stage and less than 1.5%. There was a very significantly linear connection between the application amount of Se fertilizer and the Se content of pasture (P<0.01). The linear equation of the application amount of Se fertilizer and the Se content of pasture at the seeding stage was y=1.9912x+0.1827(R²=0.9696); The linear equation at the branching stage was y=1.7394x+0.1724(R²=0.9670); The linear equation at the bud stage was y=1.5045x+0.1542(R²=0.9694); The linear equation at the initial bloom stage was y=1.2547x+0.1588(R²=0.9835); The linear equation at the flowering stage was y=1.0044x+0.1500(R²=0.9904).

Key words: Selenium(Se), Alfalfa(Medicago saliva), Growth period, Absorption, Organic selenium conversion rate, Selenium fertilizer utilization rate

摘要：

采用土壤施硒方法,研究基施硒肥对不同生育期紫花苜蓿(Medicago saliva)吸收、转化和利用硒的影响.结果表明:基施硒肥能显著提升紫花苜蓿吸收外源硒的能力(P<0.05);并随生育期延伸呈先升后降的倒"V"型变化,初花期吸收硒能力最强;而紫花苜蓿硒含量随生育期的推移而降低.基施硒肥显著提高紫花苜蓿有机硒的转化率(P<0.05),当施硒量≥0.45 mg·kg^-1时,有机硒转化率 > 50%.紫花苜蓿有机硒转化率随生育期的发展呈下降趋势;紫花苜蓿对硒肥的利用率很低,不超过1.5%;并随生育期的进程先升后降,初花期硒肥利用率最高.施硒量与不同生育期苜蓿硒含量之间存在极显著的线性关系(P<0.01),基施硒肥与苗期牧草硒线性方程为:y=1.9912x+0.1827(R²=0.9696),基施硒肥与分枝期牧草硒线性方程为:y=1.7394x+0.1724(R²=0.9670),基施硒肥与孕蕾期牧草硒线性方程为:y=1.5045x+0.1542(R²=0.9694),基施硒肥与初花期牧草硒线性方程为:y=1.2547x+0.1588(R²=0.9835),基施硒肥与盛花期牧草硒线性方程为:y=1.0044x+0.1500(R²=0.9904).

关键词: 硒, 紫花苜蓿, 生育期, 吸收, 有机硒转化率, 硒肥利用率