Investigating the Application of Phosphorus and Spraying of Micronutrients on Forage and Seed Yield in Alfalfa Ecotypes

Alfalfa (Medicago sativa L.) is known as the most valuable forage in the world due to its resistance to drought, the high quality of forage and high adaptability, high shelf life and high protein. Desirable nutrition of alfalfa is one of the key factors in the quantity and quality of seed and forage production. In alfalfa production, optimum nutrition is one of the key factors in the growth and development of the product and has a direct effect on the yield of forage and seed. The provision of phosphorus and micronutrient elements of soil in order to balance the nutrients of soil plays an important role in quantitative and qualitative improvement of the product, and it is necessary to carry out a comprehensive research on alfalfa. The purpose of this study was to investigate the effect of different levels of phosphorus and micronutrient fertilizer on quantitative and qualitative yield of alfalfa seed and forage.

In a three-year research (2011-2014), the effects of using phosphorus and micronutrients including iron, manganese, copper and zinc on quantitative and qualitative characteristics of seeds and forage production of alfalfa were studied at Golpayegan Research Station Isfahan province. For this purpose, using a split- plot experiment based on a randomized complete block design with three replications, the effect of two alfalfa ecotypes (as the main plot) and 6 levels of phosphorus and micronutrient fertilization (as a sub-plot) on the yield of seed and forage production was investigated. The main plots were consisted of alfalfa Hamedani (V1) and Rehnani (V2) and sub plots (sub-treatment) were included phosphorus (P2O5) at three levels: zero (P0), 65 (P65) and 120 (P120) kg.ha-1, and micronutrient elements in two levels of no applied (R0) and micronutrient application as spraying (R1). Parameters were measured, including forage weight, dry forage weight, seed yield, 1000 seed weight and seed vigor percentage. In the first year, there were two cutting for forage and one for seed production, in the second year there were three cutting for forage and one for seed production, and in the third year there were three cutting for forage production and one for seed production.

The results showed that there was no significant difference in forage production, seed yield, 1000 seed weight, and percentage of seed vigor between two ecotypes of alfalfa, and the average yield of forage and seed in Hamedi and Rehnani ecotypes was 35.40 and 34.77 ton.ha-1 and 498 and 487 kg.ha-1 respectively. The year had a significant effect on the yield of fresh and dry forage, seed yield and 1000-seed weight. Also, the maximum of these traits were observed in the second year. The effect of the year on vigor seed was not significant. Comparison of means showed that P fertilizer application of 120 kg.ha-1 with micronutrient spraying (P120-R1) had the highest seed production and increased of 105% compared to control treatment. The application of 120 kg.ha-1 phosphorus without micronutrient application was in the next place. The percentage of seed vigor in the treatment of 120 kg.ha-1 P, with the micronutrient application (95.1%) was significantly higher than other treatments.

In this three-year research, the study of the use of phosphorus and micronutrients on fresh and dry forage yield and some quantitative and qualitative characteristics of seed produced in two alfalfa ecotypes was carried out. The results showed that the highest amount of forage production with the amount of 42.45 ton.ha-1 and the highest amount of seed produced with the amount of 689 kg.ha-1, belonged to the treatment 120 kg.ha-1 phosphorus with micronutrient spraying.