The pattern and control of reproductive development in lychee: A review

Physiological and genetic factors influencing fruit cracking

Abstract: One of the main disorders that widely limit fruit quality and quantity is fruit cracking or splitting that is observed on the fruit skin and flesh in the preharvest phase. Besides, cracking can occur during postharvest in some fruits, mostly attributable to the environmental conditions of storage. Value of cracked fruits is reduced and these fruits are not marketable because of the poor fruit quality. Many fruits such as apple, sweet cherry, grape, plum, pomegranate, grape, persimmon, litchi, avocado, pistachio, citrus, banana as well as tomato can crack or split. There are many factors that influence fruit cracking. In this work, genetic, morphological, environmental and physiological aspects of fruit cracking are reviewed. Under the same environmental conditions, fruits from different cultivars show differences in cracking susceptibility. Some correlations have been observed between susceptibility of fruit cracking and some fruit traits (fruit shape, fruit size, fruit firmness; anatomy and strength of the fruit skin, stomata in fruit skin, cuticular properties, osmotic concentration, water capacity of the fruit pulp and growth stage of the fruit). Also, orchard management (such as irrigation and nutrition) and environmental condition (such as temperature, wind and light) can influence fruit cracking. Besides, fruit cracking is quantitative trait and is controlled by several genes. The best way to reduce fruit cracking at present would be a suitable orchard management that takes into account and try to minimize stress of the water, nutrition and physiological factors that contribute to fruit cracking. Also, the most resistant cultivars to fruit cracking that have desirable fruit quality can be selected for cultivation.

Effect of temperature on growth and flowering of litchi (Litchi chinensis Sonn.) cultivars

Abstract: SummaryModerate day/night temperatures (20/15° v. 15/10°C) increased vegetative growth and reduced flowering in the seven litchi cvs Tai So, Bengal, Souey Tung, Kwai May Pink, Kwai May Red, Salathiel and Wai Chee. At higher temperatures (25/20° and 30/25°C), vegetative growth was promoted further and flowering eliminated. Temperature also influenced the type of inflorescence formed. More leaves were formed on the panicles of trees growing at 20/15° than at 15/10°C. All terminal shoots on all cultivars produced panicles at 15/10°C. The relative order for the amount of flowering at 20/15°C was: ‘Wai Chee’>‘Salathiel’>‘Kwai May Pink’>‘Tai So’>‘Bengal’>‘Souey Tung’>‘Kwai May Red’. Cultivars which were vigorous at high temperatures produced fewer panicles at 20/15°C and fewer leafless panicles at 15/10°C. Only small differences were observed in the leaf water potential and the nutrient status of the shoots at different temperatures. Vigour and flowering of the cultivars in the glasshouse generally reflected fi...

Lychee nutrition: A review

Abstract: One of the major factors limiting fruit production in lychee (Litchi chinensis Sonn.) is lack of a suitable nutrition program. Yields may be low because of excessive vegetative growth in winter following late or heavy N fertilization. Deficiencies of N and K, and to a lesser extent of B, Zn and Cu, may limit yield by restricting the set and subsequent development of fruit. There is the possibility that soil features (pH, drainage or salinity) may impair tree health and hence indirectly reduce fruit production. Priority areas for nutrition research should include: the relationship between vegetative flushing and leaf N; the timing of fertilizer N application during flowering and fruit set; refinement of leaf and soil sampling; the possible role of K in winter dormancy; leaf symptoms of micronutrient deficiencies; and roles of Zn, B and Cu in fruit set.

Processes Influencing Floral Initiation and Bloom: The Role of Phytohormones in a Conceptual Flowering Model

Abstract: The reproductive phenologies of temperate fruit tree species are briefly introduced and compared to the reproductive phenologies of three tropical and subtropical fruit tree species. The impact of leaf and fruit development and the phytohormones they may produce on the reproductive or vegetative fate of bourse buds in apple spurs serves as the model to discuss temperate fruit flowering. In contrast, conceptual models of citrus (Citrus L.), mango (Mangifera indica L.), and lychee (Litchi chinensis Sonn.) flowering are described which propose physiological mechanisms for both flowering and vegetative flushing in trees grown in subtropical and tropical environments. Possible roles for auxin and cytokinins in shoot initiation and for gibberellins and a putative florigenic promoter in induction are discussed as they relate to the physiology of flowering and vegetative flushing of tropical species. Successful application of these conceptual flowering models through the use of growth regulators and other horticultural management techniques to control flowering of citrus, mango, and lychee is described.

The control of floral initiation in lychee: A review

Abstract: In lychee (Litchi chinensis Sonn.), there is a strong correlation between flowering and the degree of dormancy prior to the normal period of floral induction. Low temperatures and moisture stress seem to restrict vegetative growth and promote floral initiation, but there are many exceptions and many examples of interactions of factors (crop load, tree nutrition, etc.). Both cincturing (ringing) and exogenous auxins have been shown to reduce vegetative flushing and increase flowering, but the results have not always been consistent. The best prospect for improving flowering appears to be through the selection of genotypes (probably those with low vigour) which flower under conditions which are generally warmer and wetter than those in its native environment in China. An alternative approach involves a critical study of manipulative techniques which restrict vegetative flushing and promote vegetative dormancy under non-inductive conditions, i.e. cincturing, applying growth retardants and withholding irrigation and fertilizers.

Flowering and fruit-set response to temperature in the avocado cultivar 'hass'

Abstract: Avocado plants, cultivar ‘Hass’, were kept in growth cabinets at 33°C day, 28°C night ( 33 28 ); 25°C day, 20°C night ( 25 20 ); and 17°C day, 12°C night ( 17 12 ), with a 12-h photoperiod and photon flux density of 400 μE m−2 s−1 (400–700 nm). At 33 28 and 25 20 flowers opened in the morning in the female stage and again in the afternoon of the following day in the male stage (Type A floral cycle). At 17 12 the flowers opened in the afternoon in the female stage and started to reopen in the male stage 2 days later during the afternoon. They remained open overnight and started to close the following morning. Pollen tube growth and ovule penetration occurred at all temperatures. Pollen tube growth was fastest at 33 28 , but the pistils had lost the ability to support pollen tube growth by the second week of the experiment. A lower proportion of the ovules at 17 12 had an embryosac penetrated by a pollen tube. Embryo development occurred at all temperatures, but fruitlets were abscissed at 33 28 and embryo growth was very slow at 17 12 . The most suitable temperature regime for floral behaviour, pollen tube growth and embryo development was 25 20 .

The Effect of Temperature on Floral Behaviour, Pollen Tube Growth and Fruit Set in the Avocado

Abstract: SummaryAvocado plants were kept in growth cabinets at 33°C day, 28°C night (33/28); 25°C day, 20°C night (25/20); and 17°C day, 12°C night (17/12), with a 12-h photoperiod and light intensity of 26000 1x. At 33/28 and 25/20 flowers opened in the afternoon as females and again the following morning as males (type B floral cycle) with some overlap of male and female stages at 25/20. At 17/12 very few flowers had a female stage, the majority opening once only as males. The duration of the flowering period decreased with a rise in temperature as did total number of flowers opening. Reproductive growth was inhibited in favour of vegetative growth at 33/28, as exhibited by smaller floral parts and abscission of buds and flowers. The rate of pollen tube growth increased with a rise in temperature, but abnormal growth was frequently observed at 33/28 and tubes failed to reach the ovary at 17/12. Endosperm and embryo development was observed to occur at 25/20 but not at 33/28 or 17/12 although a positive effect of...

The developmental patterns of fruit tissues and their correlative relationships in Litchi chinensis Sonn.

Abstract: The growth curves of pericarp, seed and aril, and the fruit as a whole were typically sigmoidal. In contrast to early cultivars, fruits of late-maturing cultivars showed a prolonged initial slow growth phase. The pericarp growth did not differ significantly between the fruits with normal or aborted seeds. The developing embryo, however, seemed to inhibit aril growth at a certain stage of development. A close correlation was observed between pericarp and seed growth before the seed aborted. There was also a close correlation between pericarp and aril growth. The pericarp might exert its influence on aril development through an assumed “ball-skin vs. bladder effect”. Sequential influences of seed—pericarp—aril have been proposed.