Forage Production and Population of Alfalfa Weevil (Hypera Postica) in Intercropping of Alfalfa and Sainfoin

Abstract

Diversification of varieties or species within the same field can result in reduced pest population and increased yields. To study the forage production and alfalfa weevil (Hypera postica) population in alfalfa (Medicago sativa L.) and sainfoin (Onobrychis sativa) intercropping, a field experiment was carried out as a split-plot in time across 2 years (2010–12) with three replications. Treatments were: sole-cropping of alfalfa, sole-cropping of sainfoin, 50% alfalfa + 50% sainfoin as one row alternates, 50% alfalfa + 50% sainfoin as two row alternates, 75% alfalfa + 25% sainfoin, 25% alfalfa + 75% sainfoin, 10% sainfoin + 100% alfalfa, 20% sainfoin + 100% alfalfa, and 30% sainfoin + 100% alfalfa. Because of delayed emergence and growth of alfalfa in the first year, alfalfa weevil populations were monitored in the second year only. Sampling period was from April 9 to May 12, 2011. Five sampling dates were used. The results revealed that with increased ratio of alfalfa in mixed treatments, population of alfalfa weevil followed an increasing trend. In all treatment, pest population during the season showed a decreasing trend and reached zero level at the last sampling date. The highest value of dry yield was observed in 30% sainfoin + 100% alfalfa and the lowest value was obtained in sole-cropping of sainfoin and alfalfa. In both years, the highest values of land equivalent ratio were related to 30% sainfoin + 100% alfalfa treatment. We concluded that less competition between alfalfa and sainfoin caused a reduction in alfalfa yield losses from alfalfa weevil and higher plant populations in 30% sainfoin + 100% alfalfa compared to other combinations, increased forage production.