Critical stage of boron application on the seed development and quality of bush snap bean (Phaseolus vulgaris L.)

The experiment was conducted to determine the critical stage of boron (B) application on the seed development and quality of bush snap bean (Phaseolus vulgaris L.). The commercial variety of snap bean "Contender" was used in this experiment. Plants were grown in the nutrient solution formulated by John Mason for bean crops. Boron was applied at the rate of 0.05 g/L (50 ppm) of water at weekly intervals according to treatments up to the seed physiological maturity stage. The experiment was designed in single factor. Completely Randomized Design (CRD) with five treatments and four replications. All observed parameters were analyzed using the Statistical Analysis System (SAS) program. The significant effect of B application was observed during the vegetative and reproductive stages of the plant. Leaf area was significantly greater at 0 days B treatments (783.7 sq. cm/plant) as compared with control (298.8 sq. cm/plant). There were no significant effects of B in root and shoot growth. The number of flowers and pod set were increase at 0 days and 21 DAS B application and decreased continuously as time of B application was delayed. Boron was highly effective in increasing the seed size and weight. Application of B at 0 day increased the seed weight and decreased continuously as time of B application was delayed. The significant effect of B application was likewise observed on leaf and seed tissue. The amount of B in the leaf tissue was 5.67 mg/kg dry weight and seed tissue 6.43 mg/kg dry weight at 0 days B treatment and gradually reduced as application of B was delayed. Seedling emergence and vigor percentage of 0 days B applied seed were greater under favorable and unfavorable conditions as compared to control. Seed germination and seedling emergence under lab and soil conditions were 99.25% and 98.25%, respectively, at 0 days B applied treatment whereas 80% and 66.6%, respectively, in control (-B). The seed vigor was 81.0% at 0 days B applied treatment and 10.0% in control treatment under unfavorable condition. The seedling dry weight was higher (3.70g) at 21 DAS B applied seed as compared to the control treatment (1.73g). Boron applied seed showed better quality than without B. Seeds harvested from earlier B applied treatments had higher germination, vigor and produced strong seedlings as compared to without B. There were no significant differences in the vegetative, reproductive and seed quality between the 0 days and 21 DAS B applied treatments. The critical stage of B requirements for Contender bean to vegetative, reproductive and seed developmental stages was identified at 28 DAS. It can be concluded that earlier stage of B application give better performance in terms of plant growth, development and better quality of seed of bush snap bean