Litchi Growth and Compositional Changes during Fruit Development

Abstract

The changes in litchi ( Litchi chinensis Sonn .) growth and composition were studied in 4 cultivars; ‘Groff’ in Hawaii, and ‘Shui Dong’, ‘Gui Wei’, and ‘Mei selection’ in Guangdong, China. Fruit and aril growth showed a sigmoidal pattern while skin growth was slower and more linear. Aborted seeds in Groff and Gui Wei ceased growth early in the log growth phase. Normal seeded cultivars showed seed growth paralleling skin growth. Skin chlorophyll began to decrease logarithmically soon after the start of fruit growth increase, with anthocyanin production beginning about halfway through the growth period. During the rapid growth period, due principally to an increase in aril tissue, there was an increase in total sugars from 3% to 16%. The cultivars showed slightly different ratios of the 3 sugars identified: sucrose, glucose, and fructose. Titratable acidity was due mainly to succinic and malic acid. This acidity decreased over 2 weeks in the middle of the fruit growth period from 65 meq/100 g to 15 meq/100 g. Succinic acid decreased in the same period from about 350 meq/100 g to 0.4 meq/100 g and remained low for the remaining 40 days of development. Malic acid declined from 75 meq/100 g to 12 meq/100 g, and citric acid remained constant at around 3 meq/100 g. A major portion of the decline in succinic acid was due to dilution. Total phenols were low throughout the growth of the fruit. Mineral uptake into the fruit paralleled fruit growth, with potassium being the major cation.