Dr. K. P. Paudyal1 and Basant Chalise2
Abstract
Mandarin (Citrus reticulata Blanco) the most important citrus species of Nepal covers nearly 58 percent of citrus area in the country. Since only mid-season local genotypes are used commercially, its harvesting duration lasts only for three months: November-January. So, to explore the possibility of early commercial production two Satsuma mandarin (Citrus unshiu Marcvitch) varieties namely Okitsu Wase and Miyagawa Wase were evaluated for their fruit characters under screen house and open field condition at National Citrus Research Program, Dhankuta (1350 m) for two years. Total soluble solids (TSS), total acid (TA), TSS/TA ratio and sweetness of the fruits were determined from August 20 to October 10 at 10 days interval. Sweetness of the fruit was rated as sweet, slightly-Sweet and sour by organoleptic test. The fruit-taste was found sweet enough for commercial use when value of TSS/1TA ratio crossed 6:1 and therefore, this value was suggested as maturity index for the varieties. Under screen house condition with annual mean maximum temperature of 32°C, minimum temperature of 14.4° C and total heat unit of 3639, the TSS/TA ratio reached to 6 in the first week of September in Okitsu Wase, and 10 days later in Miyagawa Wase. Under open field condition, where mean maximum annual temperature (25°C) and heat unit (2718) were less, TSS/TA ratio hardly reached to 6 after 10th of October because of low TSS and high acid content in fruit juice. It indicated that warmer areas of 900-1000 m altitude could be the suitable locations for early production of the varieties. Further performance study at different altitude is needed to identify the best production climate. Farmers and consumers' reactions on fruit quality and taste of the varieties have been very positive, and their demand for the planting materials is high. Excepting maturity period, both varieties have been similar in fruit characters. Under screen house condition fruit weight ranged from 51 to 200 g, segment number from 8 to 14, peel content from 14 to 33 percent, TSS from 6.0 to 11.3 percent, TA from 0.88 to 2.0 percent and TSS/TA ratio from 4.9-12.8. Fruits from both the varieties were seedless in both the conditions.