Agro-morphological characteristics, anthocyanin, and sweetness level of Yardlong bean genotypes (Vigna unguiculata (L.) ssp. sesquipedalis)

Plant characterization is one of the activities in plant breeding before the variety can be registered. In the previous study, two parents between purple-podded and green-podded were crossed and produced several red-podded lines. In this study, we aimed to evaluate the characters of progenies (F7) yardlong beans from purple-podded and green-podded. The research was conducted in Sumawono District, Semarang, Central Java. The experiment applied a randomized complete block design (RCBD) with genotype as the single factor. Observations focused on plant characterization included leaf characteristics, flower characteristics, pod characteristics, sweetness level of pods, anthocyanin level on pods, and agronomic traits. The result showed a difference in leaf color, petiole length, leaf width, corolla color, petal color, strokes on petals color, stamen color, pistil color, pod length, pod tip color, pod color, pod texture, sweetness level, anthocyanin level. Hybridization improved the sweetness level of red/purple-podded than the cultivar checks purple-podded.


Introduction
Yardlong bean Vigna unguiculata (L.) Walp.ssp.sesquipedalis (L.) Verdc., that are commonly known as asparagus bean, Chinese long bean, long-podded cowpea, pea bean, or snake bean, is one of the legume groups which are very important and the most familiar horticulture crops with rich nutritional value in Indonesia, Thailand, Philippines, Taiwan, and China [1].In Indonesia, domestic production of yardlong bean in 2020 has increased from the previous year, which was 359,158 tons/year [2].Currently, yardlong beans have become a functional food commodity, this is because yardlong beans with purple pods contain a lot of anthocyanins which are beneficial for body health [3].The breeding programs can be carried out to obtain new cultivars with the desired characteristics [4], such as red-purple podded of yardlong bean [5].
Plant characterization is one of the activities in plant breeding before the variety can be register [6].Most germplasm accessions contain a wide diversity of morphological qualities that enable variety identification in commercial variations.The germplasm majority can be distinguished from one another merely based on morphological attributes [7].
A previous study has crossed two parents between Purple-podded x Green-podded and resulted several red-purple podded lines with agronomic traits significantly different than both parents [8].This study aims to assess the morphology of the various genotypes of Yardlong beans and identify the genotype with the highest levels of anthocyanins and sweetness, potentially serving as a new superior variety.

Characterization of Agro-morphology characters
This research used a randomized complete block design (RCBD) to generate 39 experimental units from a single factor of 11-yardlong bean genotypes over three repetitions.Each experimental unit was planted in beds measuring 6 x 1 meters with a spacing of 50 x 50 cm, where 50 cm is the distance between each row in the bed and 50 cm is the distance between individual plants in a row to ensure that there are 20 plants in each experimental row unit.792 F7 generation seeds and 144 Elder seeds are available.One seed is put into each planting hole when planting.Embroidery is done at the age of 7 DAP.Essential fertilization is done by giving manure of des of 5 tons ha -1 , which is done before planting.Further fertilization was carried out by pouring ZA and Phonska at rate 600 kg ha 1 .Pets and plant diseases were controlled mechanically and chemically using insecticides Fostin 610 EC and Abacel 16 EC.Harvesting is done by dividing two plots on each bed to harvest young and dry pods (seeds).
Observations were made on plant samples including qualitative and quantitative characters based on the Guidelines for The Conduct of Test for Distinctness, Uniformity and Stability of Yardlong Beans 2014, and the International Union for the Protection of New Varieties of Plants 2008.The evaluation was made on qualitative characters, included leaf color, anthocyanin color on leaf stalk, leaf shape, leaf stalk length, leaf length, leaf width, corolla color, petal color, flower stroke color, stamen color, pistil color, flowering age, pods length, pods end color, pods color, pods shape, pods texture, sweetness level, and anthocyanin level.
The changes in leaf color can be caused by effect of crossing between parentals (Fagiola with Aura Hijau and Fagiola with Super Putih.According to the research of [9], the green color of the leaves is influenced by major genes can be influenced by minor genes so can be affects the visible character.Differences that occur in petiole length and leaf width can occur due to biotic and abiotic factor.It supported by [10] that reported crop yield and quality are controlled from genetic factors and influenced by environmental factor so that differences can occur.Note: The numbers in the same column followed by the same letter are not significantly different in the Fisher LSD 5% at a significant level of 5%.
The color difference that occurs on the petals due to the appearance of streaks maybe the result of cross between Fagiola with Aura Hijau and Fagiola with Super Putih so there ate anthocyanin pigments in the flowers.According to [11] anthocyanins are red or purple pigments found in all plant tissues such as leaves, stems, roots, flowers, and fruit.According to the research of [5] gene that regulates the purple color of yardlong beans are dominant to green gene so the purple color can be visible.This supported by [12] research which show that the yardlong bean genotype which has green petals produces green pods.Based on the research of [13] stated that the color of the red bean pods is caused by the accumulation of anthocyanin pigments.The red color difference that occurs in the crosses is thought to be caused by modified genes.The research of [9] stated that modified genes can affect the appearance of other genes so that they change the character of the major genes.Note: The numbers in the same column followed by the same letter are not significantly different in the Fisher LSD 5% at a significant level of 5%.

Conclusions
According to the results, there are several differences in the traits of leaves, flowers, and pods, including their sweetness and anthocyanin content.Compared to the parent purple-podded, hybridization increased the sweetness level of red/purple-podded.Several genotypes have been identified as having superior characteristics on yield component traits.The genotypes FPT A 3-4-8-2 and FPT A 3-4-7-1 had the best character at the sweetness level.Additionally, the cultivar check still had the highest pod length, sweetness level, and anthocyanin level.Future hybridization projects to create superior yardlong bean varieties with high-yield components can employ the agronomic, morphological, sweetness, and anthocyanin levels identified as prospective donors.

Table 2 .
Leaf color, petiole length, leaf length, and leaf width.

Table 3 .
Corolla color, petal color, strokes on petals color, stamen color, pistil color and flowering age.

Table 4 .
Pod length, pod tip color, pod color, pod shape, dan pod texture, sweetness level, and anthocyanin level.