Optimisation of Nutrient Sources for Improving Growth, Yield, and Quality of Yardlong Bean (Vigna unguiculata subsp. sesuipedalis L.)

Abstract

In India, vegetable production is not sufficient to meet the requirements of the growing population, and the extent of cultivated land is also limited. Therefore, the potential of vegetable production must be fully exploited through the intensification of improved agronomic practices. Among the different vegetables cultivated in India, vegetable cowpea or yard long bean (Vigna unguiculata subsp. sesquipedalis L.) holds an important place due to its high nutritional value and wide consumer preference, making yield and quality significant factors. The paper aims to optimise nutrient sources for improving growth, yield, and quality of yardlong bean. A field experiment was conducted during June 2024 at the Olericulture Block of Sri Krishnadevaraya College of Horticultural Sciences, Ananthapuramu, to evaluate the effects of organic manures, inorganic fertilizers, biochar and bioinoculants on the growth and yield of yard long bean (Vigna unguiculata subsp. Sesquipedalis L.) under semi-arid conditions. The trial was laid out in a randomised block design (RBD) with 18 treatments replicated thrice. The treatments included control, rhizobium inoculation, different levels of NPK, farmyard manure (FYM), vermicompost, biochar and their various combinations. Significant variation was observed among treatments for vegetative, reproductive and yield traits. The treatment T₁₈ (35:70:35 NPK kg ha-1 + 4 t ha-1 biochar) recorded the maximum vine length (532.87 cm), leaf area index (3.42), dry matter production (2632.17 g plant-1), minimum days to flowering (32.96 days) and the highest number of leaves (219.76) and pods (66.3) per plant. It also produced the longest pods (54.76 cm), greatest pod girth (3.28 cm), maximum pod weight (15.32 g), highest number of seeds per pod (12.82) and the maximum yield (3812.37 kg ha-1). In contrast, the control (T₁) consistently recorded the lowest values across parameters. The findings clearly demonstrate that the integrated application of 35:70:35 NPK kg  ha-1 with 4 t ha-1 biochar is highly effective in enhancing growth and yield performance of yard long bean under semi-arid conditions. From the present study, it can be concluded that the application of organic manures or inorganic fertilizers alone did not produce significant improvements in the growth and yield parameters of yard long bean. Treatments involving organic fertilizers showed better performance than the control, while increasing fertilizer dosage further enhanced growth and yield attributes.