Author : Kasem Piluek

Summary : During the 1984 cool season, experiments on Chinese cabbage seed production of open-pollinated cultivars were conducted at two experiment stations in Chiangmai, Thailand. At Fang Horticulture Experimental Station which is of medium elevation (509 m), the effects of planting dates, varieties, nitrogen fertilizer, and plant growth regulators on seed yield and its components were studied. In the same period, experiments on seed production of F1 hybrid using AVRDC inbreds E-9 and 0-2 were performed at Ang Khang Experimental Station, highland (1300 m), to study the optimal planting dates, flowering synchronization, degree of self-incompatibility, and methods in maintenance of the inbred lines. For open-pollinated seed production, planting on November 20 produced a significantly higher seed yield per plant and per plot than earlier plantings because of better growth during pre-anthesis and post-anthesis development. The cultivars 77M (2/3)-43 and 77M (2)-25 had high yielding ability; however, further varietal improvement for earlier flowering and uniform bolting is necessary.