PAPAYA (CARICA PAPAYA) GERMPLASM COLLECTION AT SI SA KET HORTICULTURAL RESEARCH CENTER

Abstract

Papaya (Carica papaya) is one of the major fruit crops of Thailand and is consumed as both green and ripe fruit. There are some phenotypic variations found amongst commercial cultivars that can be used as a resource for genetic improvement. The objectives of this study were to collect, conserve and characterize papaya germplasm grown at Si Sa Ket Horticultural Research Center, Si Sa Ket, Thailand. Twenty cultivars of papaya were collected and morphological data recorded following IPGRI’s papaya descriptors, including tree height, stem color, mature leaf petiole color, shape of mature leaf, fruit shape, fruit skin color, fruit flesh color, shape of central cavity, flavors, average fruit weight, etc. The results show that tree heights at the stage of the first floral opening ranged between 68-255 cm. Stem colors were mostly greenish, ‘Khon Kaen 80’ and ‘Hawaii’ had a grayish-brown stem color, only ‘Hinan’ had a purple stem color. Colors of mature leaf petiole were mainly pale green, only ‘Hinan’ and ‘Si Thong’ had reddish-purple and pale yellow leaf petioles, respectively. There were three types of mature leaf teeth – straight convex and concave. Fruit shapes from hermaphrodite flowers can be divided into six types, lengthened-cylindrical, elongated, pear, club, reniform and oval shaped. Skin and flesh colors of the ripe fruit vary from orangish-green to reddish-orange. Central cavity spaces were round, angular, slightly star and star-shaped. Total soluble solids (TSS) of the ripe fruits ranged from 10 to 16°Brix. The average fruit weight was between 1-2 kg. The characteristic data recorded of each cultivar are basic information and will be used for further papaya research and development in Thailand.