STUDY ON THE EFFECTS OF DENSITY AND FERTILIZER ON THE GROWTH, PRODUCTIVITY OF THE SOYBEAN VARIETY DT51, SUMMER-AUTUMN SEASON IN THAI NGUYEN
Abstract
The study was conducted during the Summer-Autumn season of 2016 and 2017 in Phu Luong district and Vo Nhai district, Thai Nguyen province with the aim of determining the density and amount of fertilizer suitable for soybean variety DT51. The experiment is arranged according to the type of large plot (fertilizer), small plot (density), 3 density formulas (M1, M2, M3 corresponding to 20, 30, 40 plants /m2) and 3 fertilizer formulas. (P1: 15N: 40P: 40K + 1 ton of Song Gianh micro-organic fertilizer; P2: 30N: 60P: 60K + 1 ton of Song Gianh micro-organic fertilizer; P3: 45N: 80P: 80K + 1 ton of Song Gianh micro-organic fertilizer). The results showed that the density and amount of fertilizer in the experiment did not affect the growth time of the soybean variety DT51 (90 - 93 days). Plant height, leaf area index tends to increase with increasing density and amount of fertilizer. Number of level 1 branches tends to decrease with increasing density. The interaction between density and fertilizer on net yield is significant. The combinations with the highest and stable chromosomes over 2 years of experiment were P2M2, P2M3, P3M2, P3M3, reaching from 22.04 to 25.23 quintals/ ha (in Phu Luong), from 24.09 to 25.31. quintal / ha (Vo Nhai), net profit reached from 27.40 - 30.53 million / ha. Formula P2M2 (fertilizer level 30N: 60P: 60K combined density of 30 plants/ m2) for yield and high economic efficiency suitable for the investment of mountainous people.