Key factors affecting watermelon yield loss in different growing seasons

- Losses were caused by physiological problems, fungi, insects, and bacteria.
- Flower abortion, abnormal fruits and plant death mediated total losses.
- The Didymella bryoniae fungus was the main cause of plant death.
- Losses were greater during rainy and humid seasons.

Several biotic and abiotic factors may cause losses during the production of watermelon, Citrullus lanatus (Thunb.) Matsum. & Nakai, but there are currently few tools available to quantify losses in the different components of crop production. A crop life table can be used to understand the factors that regulate losses during crop production to establish a sustainable crop management programme. The aim of this study was to identify the critical components and quantify the key factors affecting yield loss during watermelon production using a crop life table as a tool. In 2011 and 2012, watermelon production loss factors in the field were evaluated using a completely randomised experimental design with 12 replicates, and each replicate consisted of a 64-m2 area containing 4 rows with 4 holes per row. The spacing was 2 × 2 m, and each hole initially contained 2 watermelon plants. The loss factors of physiological disturbance and insect, fungal, and bacterial attack were identified and quantified to develop a crop life table, and the primary factors regulating total watermelon yield losses were found to be flower abortion, abnormal fruits, and plant death caused by the fungus Didymella bryoniae. Watermelon yield losses are highest during rainy and humid seasons, and the results of this study show that pests and plant physiological disturbance should be jointly managed to attain higher watermelon crop yields.