EFFECT OF GROWTH RETARDANT ON GROWTH AND YIELD OF SOYBEAN

Abstract

A field experiment was carried out during summer season of 2018 at research Station of Field Crops Department - College of Agricultural Engineering Sciences - University of Baghdad / Jadriyah in order to determine the effect of spraying different concentrations of ethephon on the growth seed yield of soybean. Randomized complete block design (RCBD) arranged according to split plots used at three replicates. The main plots include three concentrations of ethephon (200, 250 and 300) mg L-1, while the sub-plots include spraying stage (flowering initiation R1, pods initiation R3 and R1 + R3) in addition to control treatment (distilled water spraying).The results showed that the spraying of ethephon at 250 mg L-1 gave lowest means of plant height (121.67 cm), lodging degree (2.07), and needed 100.50 days to reach pods initiation, and gave highest means of No. of branches (12.34 branch plant-1), leaf area (49.90 dcm2), LAI (3.33), plant dry weight (215.3 gm plant-1) and plant seed yield. Also, sprayed plant with ethephon at flowering initiation stage were significant effect on most of characters and gave lowest means of plant height (118.22 cm), lodging degree (2.02), and needed 98.44 days to reach pods initiation, and gave highest means of No. of branches (13.70 branch plant-1), plant dry weight (238.8 gm plant-1) and plant seed yield (44.19 gm plant-1). The interaction between two factors significantly effect on most characters. However, the ethephon spraying at concentration 250 mg L-1 at the flowering stage gave lowest means of plant highest and lodging degree, and needed 95.67 days to reach pods initiation, and gave highest means of No. of branches, plant dry weight and plant seed yield.