Abstract
A study was conducted at the Horticulture Farm of the Bangladesh Agricultural University, Mymensingh during the period from October 1995 to March 1998 to investigate the effect of water regime, variety and plant spacing on the physio-morphological characters and yield of cabbage. Three experiments were carried out, one in pot and two in the field. In the pot experiment and field experiment 1, six water regime treatments and two varieties of cabbage (viz. Atlas-70 and K-K cross) were included in all possible combinations. The levels of water regime treatments were, i) 95-100% field capacity (FC) throughout the growing period-T1, ii) 80±5% FC throughout the growing period- T2, iii) 60±5% FC throughout the growing period- T3, vi) 40±5% FC throughout the growing period- T4, v) 40±5% FC at vegetative period then as T, i.e. stress at vegetative stage- T, and vi) 95-100% FC vegetative period then as T4 i.e. stress at heading stage-T6. In the field experiment 2, the same six levels of water treatments in combination with three spacings (viz. 60 cm x 50 cm, 50 cm x 50 cm and 50 cm x 40 cm) were studied.
Soil moisture stress as a whole affected the yield contributing characters and reduced the yield of cabbage. In most cases, the rate of reduction was highest for severe water stress both at vegetative and heading stages, while higher reduction was observed in plants that received stress at heading stage than at vegetative stage. All the parameters except total number of loose leaves per plant, length of roots per plant and root-shoot ratio were maximum with the water treatment of 80±5% FC and minimum with 40±5% FC. In case of combined effect of water regime and variety, it was observed that the field capacity level of 80+5% maintained throughout the growing season in the variety Atlas-70, produced the maximum growth and yield of cabbage, while 40±5% FC throughout the growing period with K-K Cross gave the lowest values. The highest marketable yield was obtained from 80±5% FC with medium spacing (50 cm x 50 cm) which was found to be economically profitable. Correlation analysis with marketable yield indicated a positive high correlation co-efficient of duration of heading stage, fresh weight of loose leaves per plant, fresh weight of individual head, diameter of head, dry weight of loose leaves, dry weight of head, total dry matter, leaf area per plant, leaf area index, water content of plant, relative water content of leaf, CGR and NAR. Susceptibility index study clearly showed that varieties differ in their tolerance to water stress, and Atlas-70 was comparatively lesser susceptible than K-K Cross.
It can be concluded from the result that for better growth and profitable yield of cabbage, the soil moisture content at 80 ± 5% field capacity should be maintained throughout the entire growing season. Both excess water and severe water stress is harmful for the crop. The heading stage of cabbage was found to be very sensitive to water stress resulting drastic reduction in yield. Two flushes (peak) of growth was observed in cabbage, one at 20-35 and the other at 65 to 80 days after transplanting (DAT) when optimum moisture and other management practices are required. The treatment of 80 ± 5% field capacity in combination with medium spacing of 50 cm x 50 cm is favourable for higher yield and economic return in cv. Atlas-70.