Rendimiento y calidad de semilla de alfalfa bajo diferentes niveles de fertilización y densidades de siembra

Abstract

Yield and quality of alfalfa seed under different levels of fertilization and seeding rates. A research work was carried out in order to determine the effects of the seeding rate, and phosphorus and potassium fertilizers on the yield and quality of alfalfa seed, as well as to evaluate their effect on yield components with cv. INIA-76. Seeding rate was assessed at four levels (1, 3. 5 and 7 kg/ha); and phosphorus and potassium were at 0, 90, 180 and 270 kg P205/ha and 0, 30, 60 and 90 kg K20/ha, respectively. Treatments were selected using a Plan Puebla I matriz for three factors, obtaining fourteen combinations; in addition a control witness was included. A random block experimental design with six replications was used. Ten yield components were evaluated; one variable of physical qual ity and three of physiological seed quality. The treatment 1-90-30 showed the highest values in all the yield components and as a result it had the highest seed yield (405 kg/ha) in a single harvest. The components that showed a significant correlation with the yield were: stems with racemes per plant, racemes per plant, pods per plant, and seeds per plant; and the variable stems with racemes per plant had the highest direct effect on the yield. Treatments 3-90-30, 3-90-60 and 3-180-30 resulted in the highest physical seed quality values (2.11, 2.12 and 2.15 g, respectively) for the 1000-seed weight test. In relation to physiological seed quality there were no significant differences for the treatments. On germination capacity; nevertheless, the treatments 3-90-60, 3-180-30, 3-180-60, 5- 90- 60 and 1-90-30, showed the highest values on the vigor test. There was no significant correlation between seed yield and the physical and physiological seed quality(P<0.05),. Seeding rate affected more significantly the yield components and the seed yield; and phosphorus and potassium affected mainly the seed quality. The highest economic rate was obtained with the treatment 1-90-30.