Pod Set Efficiency in Relation to Crossing Time in Yardlong Bean (Vigna unguiculata subsp. sesquipedalis) Using Diallel Hybridization

Efficient hybridization is a major constraint in yardlong bean owing to its highly self-pollinated and cleistogamous floral nature. The present investigation was undertaken during June–September 2025 at the Department of Horticulture, PAJANCOA & RI, Karaikal, to assess the influence of crossing time on pod set percentage in yardlong bean using a 6 × 6 diallel mating design. A total of 69 genotypes were initially evaluated, from which six superior parents, namely Arka Mangala, Vyjayanthi, Lola, Vellayani Jyothika, VS 28 and VS 54, were selected based on yield and floral traits. Hand pollinations were carried out at three different time intervals viz., 6:00–7:00 a.m., 7:00–8:00 a.m. and 8:00–9:00 a.m. Pod set percentage was recorded for individual parental crosses as well as all possible diallel combinations. The experiment was laid out in Randomized Block Design (RBD) and data were statistically analysed. Results revealed significantly higher pod set during 6:00–7:00 a.m., with pod set ranging from 90.2 to 95.6% across crosses, followed by 7:00–8:00 a.m., while the lowest pod set was recorded during 8:00–9:00 a.m. Among the parents, Arka Mangala and Vellayani Jyothika exhibited superior combining ability for pod set. The study conclusively identifies early morning hours as the most effective crossing window for successful hybridization in yardlong bean breeding programmes.

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