Magnesium and boron nutrition for yard long bean (Vigna unguiculata subsp. sesquipedalis (L). verdcourt) in southern laterites of Kerala

Abstract

The study entitled “Magnesium and boron nutrition for yard long bean (Vigna unguiculata subsp. sesquipedalis (L). Verdcourt) in southern laterites of Kerala” was carried out at College of Agriculture, Vellayani during August to December, 2014 to standardize the method and time of application of fertilizers of Mg and B in the Agro Ecological Unit -8 using yard long bean as test crop. The experiment was laid out in the Instructional Farm Vellayani in Randomized Block Design with ten treatments and three replications. The treatments included a combination of magnesium as magnesium sulphate and boron as borax and were applied either in soil or as foliar at different times. Treatments were applied over and above the use of lime and NPK based on soil test and FYM as per package of practices recommendations of Kerala Agricultural University, as one time soil application as basal, one time soil application between basal and top dressing, one time soil application at top dressing, soil application in two equal splits as basal and top dressing, soil application at fortnightly intervals in equal splits. Foliar application of treatments were done at first flowering, active flowering and fortnightly intervals. Combined application of soil with half of adhoc recommendations of Mg and B as basal and foliar at active flowering was also one of the treatments. The study revealed that the use of magnesium and boron in soil and foliar application had a significant effect on the vegetative and yield characters. Foliar application of Mg and B as 2 per cent MgSO4 and 0.25 per cent borax at fortnightly intervals along with soil test based package of practices recommendations of NPK (T9) recorded the highest yield and it was on par with T8 which received foliar application of Mg and B twice at first flowering and active flowering along with soil test based package of practices recommendation. The highest cop duration (96 days) was observed in T9 and the lowest crop duration of 84 days was recorded by T1. The highest harvest index also was recorded by T9. The treatment effect was statistically 131 not significant for the quality characters like fibre content and keeping quality of pod. However the protein content was significantly influenced by the treatment. The incidence of Fusarium wilt and aphids were noticed during the crop period. But the treatments had no significant influence on them. The results of the soil analysis before and after the experiment revealed a general increase in available nutrient content and pH as a result of the treatments. The soil application of Mg and B at fortnightly intervals recorded the highest value for available Mg and B. Critical level of Mg (>120 ppm) for sufficiency in soil was attained in all soil application treatments. In the case of B, critical level of sufficiency (> 0.5 ppm) was not attained either through soil or foliar application. Application of Mg and B as soil and foliar application had a significant effect on the contents of N, P, Ca, Mg, S, Fe, Cu, Zn, Mn and B in the pod of the yard long bean. However the effect of treatments on the content of K in the pod was not significant. Whole plant analysis revealed that, the treatment had significant effect on the contents of N, P, Ca, Mg, S and B. But K, Fe, Cu, Zn, Mn were not significantly influenced by the treatments. It is concluded that, both the soil and foliar application of Mg and B significantly improved the nutrient uptake, pod yield and yield characteristics of yard long bean. The highest benefit cost ratio was noted in the treatment T8 which consisted of soil test based NPK and farm yard manure along with foliar application of 0.25 per cent borax and 2 per cent magnesium sulphate twice at first flowering and active flowering.