Effects of Irrigation Methods and Water Regimes on Occurrences of Cucumo- And Poty- Viruses in Watermelon

Abstract

The response of watermelon to Cucumber mosaic virus (CMV) and Watermelon mosaic virus (WMV) under different irrigation methods and water regimes (WRs) was investigated. Watermelon varieties; Kaolak and Sugar baby were irrigated using either sprinkler or basin at 50%, 70% and 100% WRs during the dry season. Results showed that at 3 and 5 weeks after planting (WAP) total irrigation at 100% water regime (WR₁₀₀) produced the tallest plants with basin irrigation. Mean values of 15.68 cm and 15.85 cm were obtained from Kaolak and Sugar baby respectively with basin irrigation at WR₁₀₀. However, irrigation at WR₅₀ produced shorter plants with fewer leaves. Complete yield loss was recorded on the field due to severe virus infection. Mixed virus infections were evident in some of the treatments but basin irrigation at WR₇₀ and WR₁₀₀ had no mix infection of CMV and WMV. Also, varieties were not susceptible to CMV infection at WR₇₀ and WR₁₀₀ when basin irrigation was used. However, the most severe CMV infection occurred in Sugar baby at WR₅₀ using sprinkler irrigation with virus titre of 1.29. The two varieties were susceptible to WMV irrespective of the irrigation method or WR. The highest WMV titre was 2.88 obtained from Sugar baby at WR₅₀. Total irrigation produced plants with good agronomic parameters compared with deficit irrigation. However, complete yield loss was recorded as a result of either single or double virus infections. Therefore, virus prevention and breeding for virus resistance are best approaches for the control of plant viruses.