This project aims to establish a precise irrigation model for melons to cope with the challenges brought by droughts under extreme climates. By using the physiological parameters collected in 2012-2013 as independent variables, we established a melon water status model. After optimization in 2014, it was verified in the spring of 2015. The lower limit of the positive predictive value increased from 26.7% (verification result in 2013) to 61.0% (verification result in the spring of 2015). The prediction ability has been greatly improved, providing an important index for irrigation time. The FAO crop coefficient-reference evaporation method (FAO56) is used to estimate the water demand. The crop coefficient uses the value estimated in Taiwan's local greenhouse in 2012-2013. The verification results show that full irrigation treatment using this method can save 19.9% of water compared to wet management, and can obtain fruit quality equivalent to wet management. In addition, melon seedlings are grown using light accumulation value as an irrigation parameter. The fresh weight and dry weight of the plants 14 days after sowing are better than daily scheduled irrigation, and can save 33% of water.

▲Fig. 1 The growth of melon seedlings with daily scheduled irrigation (left) and light accumulation value-based irrigation (right).

▲Fig. 2 Verification results of the spring crop of 2015.