Gypsum supplies calcium to Ultisol soil and its effect on Phytophthora nicotianae, pineapple (Ananas comosus) growth, yield and fruit quality in lower single row bed under climate change issue

Lower bed single-row pineapple cultivation could protect pineapple from soil erosion during the rainy season and drought period; however, disease problems could arise as a result of water logging. Two experiments were conducted in Ultisol soil using a lower bed single row to investigate the ability of gypsum to provide soil calcium (Ca) to the pineapple plant, plant resistance to heart rot disease, and provide a better effect on crop growth and fruit quality. In the first trial, four levels of gypsum (0, 1.0, 1.5 and 2.0 Mg·ha−1) and dolomite (2 Mg·ha−1) were spread and incorporated into soil that had been saturated with Phytophthora nicotianae inoculums. In the second trial, gypsum treatments (0, 1.0, 1.5, 2.0 and 2.5 Mg·ha−1) were used as a basic fertiliser in the row between the single beds. P. nicotianae attacked all treatments at 6 weeks after planting (WAP), and at 10 WAP, the mortality of the dolomite treatment reached 63.8%, significantly higher than that of the gypsum treatments (3.3%–14.3%). In the second experiment, gypsum significantly increased plant weight from 3 to 9 months after planting (MAP), especially when applied at 1.5–2.5 Mg·ha−1. Fruit texture, total soluble solids (TSS), and titratable acidity (TA) were not significantly different between treatments, but they all met the standards for canned pineapple grades. The results showed that soil-applied gypsum before planting provides soil calcium, meets the plant Ca requirement during an early and fast growth stage, and is free of heart rot disease.