AssessmentofYardLongBean(Vignaunguiculata (L.)Walp. subsp. sesquipedalis (L.) Verdc.) Accessions Using Minimal Descriptors

Introduction

Yard long bean [Vigna unguiculata (L.) Walp. subsp. sesquipedalis (L.) Verdc.] is an important leguminous vegetable crop widely known as Chinese long bean, string bean, snake bean, snake pea, pea bean and asparagus bean. The chromosome number is(2𝑛 = 2𝑥 = 22) and it is primarily grown for its edible green pods (Ano et al., 2008) [1] . Unlike other Vigna species, yard long bean is cultivated mainly for its crisp, tender pods, which are consumed either fresh or after cooking. It is distinguished by its exceptionally long and succulent pods, generally measuring 30-90 cm in length, with seeds typically ranging from 8-12 mm. In comparison with cowpea produces relatively shorter pods, usually about 20-30 cm long (Verdcourt, 1970) [2] . The characterization and conservation of plant genetic resources are fundamental components of modern crop improvement. Germplasm collections frequently contain accessions that differ in agronomic performance, morphology, adaptation and quality attributes. However, efficient utilization of such collections requires reliable characterization systems capable of distinguishing accessions and identifying potentially valuable phenotypes. Morphological characterization remains an important first step because qualitative descriptors are generally simple to record, inexpensive and directly applicable to accession identification and preliminary classification (Belko et al., 2013) [3] ICAR-NBPGR has undertaken systematic characterization and preliminary evaluation of vegetable and legume germplasm to document agro-morphological variation and facilitate the identification of useful accessions. Recent large-scale characterization of yard long bean germplasm conserved in the Indian National Gene bank also demonstrated considerable diversity for plant growth habit, flower colour, pod colour and seed colour, emphasizing the usefulness of morphological characterization for this crop. The experiment was laid out in a Completely Randomized Block Design(CRBD)with two replications. The genotypes were sown by dibbling at a spacing of 60 × 40 cm, maintaining ten plants per genotype. Recommended agronomic practices were followed throughout the crop period. Plant growth habit was classified as pole or bushy. Flower colour was categorized as light purple, purple, dark purple and white, while pod colour was classified as light green, dark green, green, red, green with purple tip and light green with purple splashes. Seed colour included red, buff, mottled brown, black, mottled red, mottled grey, deep red, light red, white and brown. Seed shape was classified as kidney, rhomboid and ovoid, whereas seed-eye pattern was recorded as medium or small eye listed in (Table 1)

Materials and Methods

A field experiment was conducted during

Results And Discussion

The evaluated germplasm was predominantly characterized by a poletype growth habit, indicating the dominance of climbing forms within the collection. Bushy growth habit was also observed in the collection, demonstrating that contrasting plant architectures were represented among the germplasm. The occurrence of both pole and bushy forms is of particular interest because plant style has suggestions for crop management, staking requirements, plant density and suitability for different production systems. Based on flower colour the accessions are classified into Light purple, Purple, Dark purple, White colour types. Light purple colour flower were observed in 14 genotypes, dark purple were recorded in 9 genotypes, white colour observed in IC 488068 and JPJN/19-035. Purple colour were recorded in 17 and predominant in the studied germplasm. Similar observations were reported by Saidaiah et al. (2019) in yard long bean. Based on pod colour, the genotypes were classified into light green, dark green, red, green, light green with purple splashes and green with purple tip types. Light green pods were recorded in 25 genotypes, indicating that this was the predominant pod colour. Dark green pods were observed in 6 genotypes, while red and green pods were recorded in 4 genotypes each. Light green pods with purple splashes and green pods with purple tip were observed in one genotype each.

Similar findings were reported in Rambabu et al. (2016) [4] , Devan et al. (2021) [5] In yard long bean Based on seed colour, the genotypes exhibited considerable variation, with red, buff, mottled brown, mottled red, mottled grey, deep red, black, light red, white, brown and mottled seed colours. Red seed colour was recorded in 17 genotypes, indicating that it was the predominant seed colour among the genotypes evaluated. Buff seed colour was observed in five genotypes, while mottled brown and black seed colours were recorded in four genotypes each. Mottled red seed colour was observed in three genotypes, whereas deep red, mottled grey and light red seed colours were recorded in two genotypes each. White, brown and mottled seed colours were observed in one genotype each, indicating the presence of considerable diversity for seed colour among the yard long bean germplasm. Similar findings earlier were reported in Tantasawat et al. (2010) [6] in Yardlong bean. Considerable variation was observed among the genotypes with respect to seed shape, which included kidney, rhomboid and ovoid types. The kidney shape was predominant, being recorded in 33 genotypes. Rhomboid-shaped seeds were observed in IC 202647 , IC 622601 , IC 259058 , IC 622580 and IC 622585 . Ovoid-shaped seeds were recorded in IC 586952 , IC 586954 ,TCR-60andTCR-77.Thepredominanceofkidneyshapedseedsindicated that this was the most common seed shape among the evaluated yard long bean genotypes.The present findings are in accordance with those reported by Nasrin et al. (2024). Considerable diversity was observed among the evaluated genotypes with respect to seed-eye pattern, which was categorized into medium and small eye types. The medium seed-eye pattern was predominant, occurring in 31 genotypes, whereas the small seed-eye pattern was recorded in 11 genotypes. The higher frequency of the medium type indicates its wider distribution within the germplasm studied. Overall, the variation in seed-eye pattern provides useful information for the morphological characterization and identification of yard long bean genotypes.

Conclusion

The present investigation revealed considerable variation in the qualitative morphological characters of the 42 yard long bean (Vigna unguiculata subsp. sesquipedalis Verdc.) genotypes. Pole growth habit, purple flowers, light green pods, red seeds, kidney-shaped seeds and medium seed-eye pattern were predominant,while contrasting types were also observed for the characters studied, indicating appreciable phenotypic diversity within the germplasm. The presence of bushy types and diverse flower colour, pod and seed characteristics provides useful variation for selection in breeding programmes. The observed morphological differences can also aid in the identification and characterization of individual genotypes. Standardized descriptors proved effective for documenting the existing diversity within the germplasm collection. The information made will be useful for germplasm identification, classification, conservation and future utilization in yard long bean improvement programmes.

References

1. Ano AO, CIUbochi. Nutrient composition of climbing and prostrate vegetable cowpea accessions. African J. Biotech. 2008;7(20):3795-3798.
2. Verdcourt B. Studies in the leguminosae-Papilionoideae for the flora of tropical East Africa: IV. Kew Bulletin. 1970;24(3):507569.
3. Belko N, Zaman AM, Diop NN, Cisse N, Zombre G, Ehlers JD, Vadez V. Restriction of transpiration rate under high vapour pressure deficit and non-limiting water conditions is important for terminal drought tolerance in cowpea. Plant Biology. 2013;15(2):304-316.
4. Rambabu E, Reddy KR, Kamala V, Saidaiah P, Pandravada SR. Genetic divergence for quality, yield and yield components in yard long bean [Vigna unguiculata (L.) Walp. ssp. sesquipedalis Verdc.]. Legume Research. 2016;39(6):900-904.
5. Devan SR, Rathod V, Chinthan KN, Lakshmidevamma TN, Deepashree G, Shilpashree N, Manjunathagowda DC. Morphological Characterization, Trait Variability and their Association, and Diversity Analysis Among Yard Long Bean (Vigna unguiculata (L.) Walp. subsp. Sesquipedalis (L.) Verdc.) Genotypes. 2021.
6. Tantasawat P, Trongchuen J, Prajongjai T, Seehalak W, Jittayasothorn Y. Variety identification and comparative analysis of genetic diversity in yardlong bean (Vigna unguiculata spp. sesquipedalis) using morphological characters, SSR and ISSR analysis. Scientia Horticulturae. 2010;124(2):204-216.
7. Pidigam S, Munnam SB, Nimmarajula S, Gonela N, Adimulam SS, Yadla H, Bandari L, Amarapalli G. Assessment of genetic diversity in yard long bean (Vigna unguiculata (L.) Walp subsp. sesquipedalis Verdc.) germplasm from India using RAPD markers. Genetic Resources and Crop Evolution. 2019;66(6):12311242.
8. Sultana NJ, Das KR, Al Masum MA, Ahmad M. Morphological Characterization of Yardlong Bean for Pod Borer Infestation. Fundamental and Applied Agriculture. 2024;9(4):277-282.
9. How to cite this article: Babu MP, Rajasekhar M, Saidaiah P, Srinivas J, Mallesh S. AssessmentofYardLongBean(Vignaunguiculata (L.)Walp. subsp. sesquipedalis (L.) Verdc.) Accessions Using Minimal Descriptors. International Journal of Research in Agronomy. 2026;9(9):1581-1584. doi: https://www.doi.org/10.33545/261806 0X.2026.v9.i9u.6734