Effect of intra-raw spacing and nitrogen fertilizer Rate on yield and yield components of cabbage (brassica Oleracea var.Capitata. L) at Holeta, central Highlands of Ethiopia

Abstract

A field experiment was conducted to investigate the effect of intra-row spacing and nitrogen fertilizer rate on yield and yield components of cabbage. The study was conducted from December 2010 to May 2011 at Holeta Agricultural Research Center. Three intrarow spacing (20, 30 and 40 cm) and four nitrogen fertilizer levels (0, 50,100 and 150 kg/ha) were used. The experiment was laid out in Randomized Complete Block Design (RCBD) in 3x4 factorial arrangements with three replications. Copenhagen market variety of cabbage was used for this experiment. Results indicated that head weight and unmarketable yield were very highly significantly (P<0.001) affected by the interaction effect of intra-row spacing and nitrogen fertilizer rates. The highest head weight (1.52 kg/plant) and lowest unmarketable yield (0.83 t/ha) were obtained at the interaction of 40 cm intra-row spacing with 150 kg/ha nitrogen fertilizer rates. Days to maturity, leaf number, leaf area, plant spread, head height, head diameter, whole plant fresh weigh , dry matter, harvest index and nitrogen left after harvest were very highly significantly (P<0.001) affected by nitrogen fertilizer rate and intra-row spacing. Wider plant spread (51.8 cm), larger leaf number (13.7), wider leaf area (463 cm2 ), longer head height (16.7 cm), wider head diameter (16.6 cm) were recorded at higher (150 kg/ha) nitrogen fertilizer rate. Higher marketable yield (78.2 t/ha), higher total yield (80 t/ha), higher harvest index (0.8) and higher nitrogen left after harvest (0.22%) were also recorded at higher nitrogen fertilizer rate (150 kg/ha), but lower dry matter percentage (7.78%) was recorded at this rate. Intra-row spacing of 40 cm was found to be superior for plant spread, head diameter, head height, leaf number, leaf area, whole plant fresh weight and nitrogen left after harvest. For higher gross yield 20 cm intra-row spacing was superior. Higher profitable yield (78 t/ha) or birr 230,530.00 per hectare was obtained at the combination of 150 kg/ha nitrogen fertilizer rate with 20cm intra row spacing. Correlation analysis indicated that marketable yield was significantly correlated with outer leaf number (r=0.71***), head height (r=0.73 ***), head diameter (r=0.87***), whole plant fresh weight (r=0.8***), head weight(r=0.67) and harvest index (r=0.7***). Results of current investigation revealed that 20 cm intra-row spacing and 150 kg/ha nitrogen fertilizer rates can be used for higher marketable yield and profitability. Farmers at Holeta could therefore be advised to use this combination for high profitable cabbage yield. However, further investigations may be suggested to be carried out on different soil type, at different seasons, year and location so as comes up with precise and comprehensive recommendation.