Application of pesticide combinations on watermelon affects pollen viability, germination, and storage

Abstract

To increase watermelon (Citrullus lanatus) production, pesticides are now being used in higher quantities. Many pesticide combinations are harmful to seed production. This study was carried out to assess the effects of pesticide combinations (i) α-cypermethrin + mancozeb (α-CpMa) and (ii) λ-cyhalothrin + acetamiprid + metalaxyl + copper oxide (λ-ChAMeC) on in vitro germination, viability, and storage of watermelon pollens. Pesticides were applied on field, on three varieties of watermelon plants (kaolack, F1-koloss, and F1-sugar dragon), before and during blooming. The pollens were subjected to viability and germination tests directly after harvesting, or stored at +10°C or −20°C before testing. In vitro germination and viability of pollen were carried out on modified Brewbaker and Kwack medium. Α CpMa and λ-ChAMeC inhibited pollen germination in all the three varieties of watermelon. α-CpMa was the most harmful pesticide when applied during blooming, with up to 26.5% decrease in pollen germination. A decrease of pollen germination and viability was also observed after 4 and 7 days of storage. Pollen from the variety kaolack showed a higher germination rate and, freezing at −20°C was the better storage condition. These results could help to scale up pollen sharing and seed production in watermelon breeding programs.