Effect of water and nitrogen on Chinese cabbage [Brassica chinensis]
1990
Suntaree Yingjajaval (Kasetsart Univ. Kamphaeng Saen Campus, Nakhon Pathom (Thailand). Tropical Vegetable Research Center)
Three experiments 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. ASVEG 1 grown in late cool season performed the best with 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 tipburn incidence. Increasing irrigation rate from 50% to 100% of PET could increase the yield by 36%, while side-dressing with more ammonium sulfate from 30 to 120 kg/rai increased the yield by only 12%. 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 increased with the water application rate and inversely correlated to the rate of tipburn. High production inputs are necessary to assure satisfactory yield of short duration crop. Chinese cabbage, the early cultivar ASVEG1 in particular, can be harvested 35-40 days after transplant. The crop will absorb nutrient in a linearly increasing amount every day from the beginning of head formation to harvesting time, so a steady and sufficient supply of nutrients, especially nitrogen and potassium is necessary until harvest. Water requirement, is less studied. Water is normally applied in an excessive amount. But in summer season, water is not always available.
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