摘要：Alfalfa (Medicago sativa L.) is a vitally important forage crop. Due to its perennial characteristics, agradual decline of soil nutrients (especially micronutrients) leads to a reduction of grass quality.Numerous studies have reported a direct relationship between ferrite levels and physiological functionof plants. The present study investigates the impact of ferrite levels on alfalfa and tests five ferroussulphate concentrations and three spraying frequencies. To investigate the influence of iron on alfalfaphotosynthesis and iron uptake, we measured photosynthetic capacity and hay yield of alfalfa on irondeficient soil. We furthermore investigated the effects of iron on alfalfa yield and explored its mechanismof action. The results revealed that the wiron fertilizer sprayed at the appropriate concentration(0.6%-0.8%) increased the Fv/Fm and Fv/F0 of the photosystem II complex. Spraying furthermoreincreased electron transport rate and photochemical quantum yield, reduced non-irradiative energydissipation, and hence increased the photosynthetic rate and hay yield of alfalfa. Two applications of0.6% ferrous sulphate spray increased the chlorophyll concentration of alfalfa by 26%. Three applicationsincreased hay yield by 22% compared with check. Two applications of 0.8% spray increasedphotosynthetic rate by 42% and three applications increased the iron content of leaves by 117%.These results indicated that applying Fe (foliar-applied) from seedling to squaring stage improved thephotosynthetic capacity and yield of alfalfa.
