Estimation of growth stage-based nitrogen supply levels for greenhouse semi-forcing zucchini cultivation

An estimation of the requirement of minerals based on growth stage and cropping pattern is very important for greenhouse zucchini. This study was performed at farmer’s field which was applied with a fertigation system and a semi-forcing cultivation from Feb. to July in 2014, and nitrogen levels were set up with x0.5, x0.75, x1.0 and x1.5 of the NO₃-N-based soil-testing recommendation for zucchini cultivation. Top dressing of nitrogen (basal : top = 4 : 6) and potassium (basal : top = 3 : 7) was applied with an interval of every two weeks from two and six weeks after transplanting, respectively, and phosphorus was totally supplied with basal dressing. The nitrogen uptake was the order of x1.0, x0.75, x1.5 and x0.5, phosphorus, x1.0, x0.75, x0.5 and x1.5, and potassium, x0.75, x1.0, x1.5 and x0.5. From these results, it was suggested that highest mineral uptake could be reached between x0.75 and x1.0 of the NO₃-N-based soil-testing recommendation. In conclusion, nutrient management based on the growth stage was proven to be better method for favorable growth and yield of zucchini.