Effects of drought stress and super absorbent polymer on susceptibility of pepper to damage caused by Aphis gossypii Glover (Hem.: Aphididae)

Abstract

Pepper plant Capsicum annuum L. has great nutritional value and many pharmaceutical properties but its sensitivity to pests such as Aphis gossypii Glover, especially in drought stress conditions, has limited its production. To evaluate the effect of drought stress on the population and damage rate of this pest in greenhouse condition, four moisture treatments including; full irrigation, 15, 30 and 45 percent of water deficit, and four treatments with different amounts of super absorbent polymer (SAP) containing 2, 4, 6 and 8 g per pot were separately performed in completely randomized design. Four weeks after applying drought stress, the pots were moved near the aphid sources. Density of aphids was examined after one month of infestation, and the plant growth characteristics after two months. It was found that the increase in severe drought stress (45% DI45) significantly raised the population of this pest and remarkably decreased plant growth rate and yield. However, the low stress of drought (15% DI15) not only caused relative reduction of insect's population, but also saved water consumption and increased crop yield. However, the insect population was elevated as a result of increase in the amount of irrigation. Although the excessive use of SAP (8 g) increased the aphid population, the current experiment showed the use of 4 and 6 g of super absorbents could minimize the irrigation stress, decrease the pest population and improve yield of the plants by retaining the moisture in drought conditions.