[Effects of selenium on Chamaecrista rotundifolia growth, nutrient absorption and nitrogen-fixing ability]

In this paper, a field experiment was conducted on a red soil of South China to study the effects of applying selenium fertilizer on the growth, forage quality and nitrogen-fixing ability of Chamaecrista rotundifolia. The results showed that applying 75, 150, 225 and 300 g Se x hm(-2) could increase the plant height, branch number, dry root weight and dry forage yield by 0.3% - 6.2%, 65.1% - 79.5%, 155% - 252% and 30.6% - 54.1%, respectively. The total nitrogen, total phosphorus and total potassium contents of plant were increased by 21.79% - 41.46%, 20.74% - 34.67% and 34.3% - 62.4%, respectively, and the raw protein, raw fat, raw fiber and amino acid contents were increased by 21.79% - 41.46%, 1.4% - 89.6%, 34.1% - 56.6% and 6.33% 63.24%, respectively. Among the 4 doses, 150 g Se x hm(-2) was the most effective and suitable application amount. The selenium content in plant after applying 300 g Se x hm(-2)(S4) was 0.695 mg x kg(-'), with an increase of 0.658 mg x kg(-1) compared to no selenium fertilization. There was a significantly positive correlation between plant selenium content and applied selenium (R2 = 0.9666**). The root nodule weight, number and nitrogenase activity in treatment 150 g Se x hm(-2)(S2) were respectively 131.7%, 114.3% and 1417.9% higher than those of no selenium fertilization. The correlation between applied selenium and nitrogenase activity was also significant (R2 = 0.9606*).