Production, diversity and utilization of durian in Thailand

Thailand is one of the largest fruit producers and exporters. The ten most economically important fruits in Thailand were worth about 1.16 million baht in 2014, with an overall product volume of just over 8.85 million metric tons (MT). The overall quantity of fruit product exported in 2014 was about 1.82 million MT, worth around 56,749 million baht, making up about 8.71% of the total agriculture product. Durian is one of the most popular and famous seasonal fruits in Thailand. The area planted to durian in Thailand in 2014 was about 104,308 ha, with annual total yield of 631,631 metric MT. The average yield was about 6919 kg ha-1 and farm price about 41.23 baht kg-1. Thailand exported a total of 378,808 MT, valued at 13,428 million baht, made up of 12,206 million baht for fresh durian, 998 million baht for frozen durian, 45 million baht for durian paste and 179 million baht for preserved durian. To enhance durian diversity and utilization, a breeding program was conducted in Thailand using conventional breeding procedures. Durian germplasm was surveyed and collected from various horticultural research centres (HRCs) of the Department of Agriculture, between 1956 and 2015. Characterization and evaluation were done using morphological and DNA fingerprinting. Clonal selection of existing commercial cultivars and chance seedling trees was conducted between 1986 and 1988 at Chanthaburi HRC, where at least 68 cultivars were collected, characterized and evaluated. Currently, more than 800 accessions have been collected and are held at HRCs. Eighteen cultivars were selected as parent plants for 55 reciprocal crosses and produced 7634 F1 hybrid seedlings between 1986 and 1990. Between 1999 and 2006, some of these F1 hybrids were characterized and evaluated for 26 characters; five characters were chosen as the main criteria for F1 selection, along with early, moderate and late maturity, percentage of fruit setting and yield. The variation of F1 hybrids was investigated and the Thai Durian Standard (1998) was also applied for selection. Twenty-nine promising F1 hybrids were confirmed for their quality over at least 3 years and compared with commercial cultivars for 7 years. The first three promising lines were selected to be new recommended F1 hybrid cultivars, namely, 'Chanthaburi 1', 'Chanthaburi 2' and 'Chanthaburi 3', in 2006. DNA fingerprinting for these promising lines was studied to identify their specific characters or breeding patterns. Also, 253 lines of the F2 generation, 4278 F1 lines from 51 new crosses between 1998 and 2002, 110 interspecific hybrids from 45 crosses between 1988 and 1992 and 21 crosses in 2000 are being investigated to produce new F1 hybrids with high tolerance to Phytophthora palmivora, high quality, yield and varying fruit quality and size to meet market requirements. To date, another three promising F1 hybrid cultivars have been released as new recommendations, namely 'Chanthaburi 4', 'Chanthaburi 5' and 'Chanthaburi 6'. Moreover, another three promising lines will be released: an early-maturity line, 'Chanthaburi 7', a moderate-maturity line with high quantity flesh which is good for processing, 'Chanthaburi 8', and a late-maturity line, 'Chanthaburi 9'. These new hybrids are being compared commercially for yield and market acceptance.