Growth and Yield Responses of Sweet White Lupine (Lupinus albus L.) to Row Spacing and Rates of Blended NPSB Fertilizer

Abstract

ABSTRACT
Sweet white lupine (Lupinus albus L.) is economically an important crop in Ethiopia. However, its productivity is very low as compared to the productivity of world sweet white lupine which is attributed to poor agronomic practices like inappropriate seeding rate, row spacing, low soil fertility and lack of improved seed. Therefore, a field experiment was conducted to evaluate the effect of different rates of NPSB fertilizer and inter row spacing on yield and yield components of sweet white lupine. Five NPSB fertilizer rates (0, 50, 100, 150, 200 kgha-1) and three inter row spacings (20, 30, 40 cm) were tested in factorial arrangement in randomized complete block design with three replications. The maximum values for total branches (14.18), effective branches (6.61), number of pods per plant (52.17), number of seeds per plant (158.58), and harvest index (31.96%) were observed at 40 cm inter-row spacing. These results were statistically similar to those at 30 cm spacing for most parameters, except for the number of pods per plant. On the other hand, the highest thousand seed weight (99.21) was obtained by 30 cm row spacing that was at par with 20 cm row spacing. Furthermore, the interaction effects of NPSB fertilizer rates and inter row spacing significantly affected plant height. Thus, the highest plant height (108.87cm) was recorded from the treatment applied with 150 kg ha-1 at 20cm inter row spacing. Whereas, yield components and yield of sweet white lupines were not statistically affected by rates of NPSB and inter row spacing. Also, from the partial budget analysis, application of 100 kgha-1 NPSB at 40cm inter row spacing gave the best profitable yields with the highest net benefit and marginal rate of return (6881.48) followed by those plot fertilized with 150 kgha-1 NPSB at 30cm row spacing (3144.29) and 50 kgha-1 NPSB at 40cm row spacing (2868.71). Based on the results obtained from the study, producing sweet white lupine at 40cm inter row spacing and applying 100 kgha-1 NPSB fertilizer rate gave better growth and yields and can be recommended for producers in the study area and the like.