2017 Volume 16 Issue 1 Pages 7-18
To utilize the irrigation function of Farm-Oriented Enhancing Aquatic System (FOEAS) in an upland field converted from a paddy field, we examined the effect of sub-irrigation at different growth stages of broccoli and levels of precipitation. Summer-sown fall-harvest broccoli was transplanted in a large pot of andosol or gray lowland soil under rain shelter. The level of feed-water in a connected tank was automatically maintained at –30 cm from the soil surface. Plants were irrigated in each cultivation period (Early, Middle, Late, and Whole periods) under low-level precipitation (25% of monthly average amount of precipitation). By comparing with plants supplied with 25% of the monthly average amount of precipitation, soil water suction in sub-irrigated plots remained low, and plants grew larger. In the Middle and Whole plots, plants had a roughly equal head weight to those in the 100% precipitation plot. The interruption of irrigation at three weeks before harvest improved the preservation of broccoli florets. The effects of sub-irrigation were dependent on the levels of precipitation, and sub-irrigation with 100% precipitation decreased the head weight and shortened the shelf life. The results indicate that sub-irrigation according to the growth stage of plants and rainfall may prevent drought and increase the yield and quality of broccoli.
