Effect of Water and Nitrogen on Chinese Cabbage

Abstract

Three experimental were carried out on Chinese cabbage. The late hybrid “Elephant” commercial cultivar was grown during summer of 1986, and the early hybrid ASVEG #1 cultivar was grown during the late cool season and summer season of 1987. Three rates of water application – 50% 75% and 100% of potential evapotranspiration ( PET ), and Four rates of ammonium sulfate side – dressing--30, 60, 90 and 120 kg/rai were studied. The results indicated that ASVEG # 1 grown in late cool season performed the best with effect the overall averaged head yield of 4.1 t/rai. The yields of Chinese cabbage grown in summer were 1.58 t/rai for “elephant” brand and 1.17 t/rai for ASVEG#1. Water had direct effect on the head yield and and tipburn incidence. Increasing the irrigation rate from 50% to 100% of PET could increases the yield by 36% while side-dressing with more ammonium sulfate from 30 to 120 kg/rai increased the yield by only 12%. At the same time, the increase in water application rate reduced the tipburn rate to 46%, but the tipburn rate was slightly increased by the NH₄-N side-dressing. Calcium content of the head leaves was found to increase with the water application rate and inversely correlated to the rate of tipburn. Water management was considered to be a more practical way of alleviating tipburn damage than that of applying calcium to correct the calcium status in the plant. High production inputs are necessary to assure satisfactory yield of short duration crop. Chinese cabbage, the early cultivar ASVEG # 1 in particular, can be harvested 35-40 days after transplant. The crop will absorb nutrient in a linearly increasing amount every day form the beginning of head formation to harvesting time, so a steady and sufficient supply of nutrients, especially nitrogen and potassium is necessary until harvest (Takahashi, 1981). Water requirement, on the other hand, is less studied. Water is normally applied in an excessive amount. But in summer season, water in not always available. There is a need to understand the response of vegetable to both water and nutrient. This investigation was set up to study Chinese cabbage production during the summer season as effected by water and NH₄-N side-dressing requirement.