The effect of growing environment on the performance of two strawberry (Fragaria ×ananassa) cultivar/breeding lines ('Festival' and 'Breeding Line 1') was studied in south-eastern Queensland, Australia. Plants were grown under tunnels or outdoors. Supplementary over-head irrigation was given to the plants outdoors to provide a water supply (irrigation + rainfall) about twice that of the long-term average rainfall for the area. Half the plants under the tunnels or outdoors received the standard sprays to control grey mould, while the other half of the plants received none of these sprays. The yields of the plants in the dry environment under the tunnels (without over-head irrigation) were more than double the yields of the plants in the wet environment outdoors (with over-head irrigation). This result indicates that losses that may occur during a wetter than average season. The plants under the tunnels had lower incidences of rain damage and grey mould than the plants outdoors. There were higher incidences of powdery mildew, and of small and misshaped fruit under the tunnels. Only cultivars with some resistance to powdery mildew should be grown under protected cropping. Spraying reduced the incidence of grey mould outdoors but not under the tunnels. Crops growing under protected cropping in Queensland probably do not need to be sprayed for grey mould.

SUMMARY The results of research into the water relations and irrigation requirements of lychee are collated and reviewed. The stages of plant development are summarised, with an emphasis on factors influencing the flowering process. This is followed by reviews of plant water relations, water requirements, water productivity and, finally, irrigation systems. The lychee tree is native to the rainforests of southern China and northern Vietnam, and the main centres of production remain close to this area. In contrast, much of the research on the water relations of this crop has been conducted in South Africa, Australia and Israel where the tree is relatively new. Vegetative growth occurs in a series of flushes. Terminal inflorescences are borne on current shoot growth under cool (<15 °C), dry conditions. Trees generally do not produce fruit in the tropics at altitudes below 300 m. Poor and erratic flowering results in low and irregular fruit yields. Drought can enhance flowering in locations with dry winters. Roots can extract water from depths greater than 2 m. Diurnal trends in stomatal conductance closely match those of leaf water status. Both variables mirror changes in the saturation deficit of the air. Very little research on crop water requirements has been reported. Crop responses to irrigation are complex. In areas with low rainfall after harvest, a moderate water deficit before floral initiation can increase flowering and yield. In contrast, fruit set and yield can be reduced by a severe water deficit after flowering, and the risk of fruit splitting increased. Water productivity has not been quantified. Supplementary irrigation in South-east Asia is limited by topography and competition for water from the summer rice crop, but irrigation is practised in Israel, South Africa, Australia and some other places. Research is needed to determine the benefits of irrigation in different growing areas.

Experiments were conducted to determine the effect of time of planting, plant size, and nursery-growing environment on the performance of bare-rooted ‘Festival’ strawberry plants ( Fragaria × ananassa ) at Nambour in southeastern Queensland, Australia, over 3 years. Yields were best with a planting in mid-March (1013 g/plant), with lower yields with a planting in early March (711 g/plant), late March/early April (765 g/plant), mid-April (671 g/plant), or late April/early May (542 g/plant). Plants obtained from Stanthorpe in southern Queensland, a warm-growing environment, were just as productive (695 g/plant) as those from Toolangi in Victoria (710 g/plant) or Kempton in Tasmania (701 g/plant), two cool-growing environments. In contrast, large plants from these nurseries with crown diameters ranging from 10 to 17 mm had 17% higher yields than small plants with crown diameters ranging from 6 to 10 mm (751 vs. 642 g/plant). These results suggest that planting in mid-March is optimal for ‘Festival’ in this environment. Lower yields with an earlier planting reflected the small size of the plants, whereas lower yields with later plantings reflected the shorter growing seasons. It can also be concluded that plant size is more important than nursery-growing environment in determining the productivity of strawberry fields in southeastern Queensland.

The productivity of containerized and bare-rooted plants of strawberry ( Fragaria × ananassa ) was investigated over 4 years in southeastern Queensland, Australia. In the first experiment, plants in small, 75-cm 3 cells were compared with bare-rooted plants of ‘Festival’ and ‘Sugarbaby’. A similar experiment was conducted in year 2 with these two cultivars, plus ‘Rubygem’. In year 3, plants in large, 125-cm 3 cells were compared with small and large bare-rooted plants of ‘Festival’ and ‘Rubygem’. Treatments in each of these experiments were planted on the same date. In the final experiment, plants in large cells and bare-rooted plants of ‘Festival’ were planted in late March, early April, mid-April, or early May. The plants grown in small cells produced 60% to 85% of the yields of the bare-rooted plants, whereas the yield of plants in large cells was equal to that of the bare-rooted plants. Containerized plants are twice as expensive as bare-rooted plants (A$0.60 vs. A$0.32) (A$ = Australian dollar), and gave only similar or lower returns than the bare-rooted plants (A$0.54 to A$3.73 vs. A$1.40 to A$4.09). It can be concluded that containerized strawberry plants are not economically viable in subtropical Queensland under the current price structure and growing system. There was a strong relationship between yield and average plant dry weight (leaves, crowns, and roots) in ‘Festival’ in the last three experiments, where harvesting continued to late September or early October. Productivity increased by about 18 g for each gram increase in plant dry weight, indicating the dependence of fruit production on vegetative growth in this environment.

Plugs or containerized plants can offer several advantages over traditional bare-rooted runner plants for strawberry (Fragaria x ananassa) production. Some of these benefits include easier planting, better establishment, fewer pests and diseases, and lower water use during plant establishment resulting in less leaching of applied fertilizers. Plugs also offer the potential for mechanical planting. In some areas of Europe and North America, plugs provide earlier production, greater productivity and larger fruit than runners. Research has also shown that the plants can be grown under short days and low temperatures to manipulate flower initiation and fruiting. Plugs are more expensive to buy compared with runner plants, and will only be adopted by industry if the extra costs are matched by convenience, resource conservation, increased fruiting and returns to producers. We investigated the productivity of 'Festival' and 'Sugarbaby' propagated as plugs (75 cm(3) containers) and runners from Stanthorpe in southern Queensland (elevation of 872 m), and grown at Nambour on the Sunshine Coast (elevation 29 m). At planting, the plug plants weighed 0.8 +/- 0.1 g DW compared with 5.3 +/- 0.5 g DW for the runner plants. 'Sugarbaby' plugs were larger than 'Festival' plugs (3.3 +/- 0.6 g versus 2.9 +/- 0.6 g). The differences in growth at planting were maintained until the third week of July (day 94), with the plug plants weighing 17.8 +/- 2.2 g, and the runner plants 21.4 +/- 2.3 g. The proportion of plant dry matter allocated to the leaves increased over time from 59 to 70%, while the proportion allocated to the roots decreased from 21 to 10%. Harvest commenced after 60 days, with the plug plants yielding only 60% of the yields of the runner plants up until 8 August or day 109 (14.2 +/- 1.4 g plant(-1) week(-1) versus 23.6 +/- 1.9 g plant(-1) week(-1)). 'Festival' (22.2 +/- 2.0 g plant(-1) week(-1)) had higher yields than 'Sugarbaby' (15.5 +/- 1.5 g plant(-1) week(-1)), even though plants of the latter were larger. Average fruit weight was 15.6 +/- 0.3 g, with no effect of cultivar, plant type or harvest time. In other words, the differences in yield between the various treatments were due to differences in fruit set. The lower yields of the plug plants probably reflect their small size at planting. Future research should determine whether plugs grown in larger cells (150 to 300 cm(3) as in the USA and Europe) are more productive. Tips to be grown in larger containers should be harvested earlier than those for small cells to maximize root growth of the plug plant. This will probably extend the time required from harvest of the tips and potting them from the current four to five weeks, to eight to ten weeks.

This chapter on litchi (Litchi chinensis) and longans covers the following: soil and plant water relations; irrigation requirements; tree water use; irrigation in China, Vietnam and India; soil water uptake; relationship between gas exchange and tree water status; models of leaf gas exchange; relationship between growth and weather; effects of drought on the growth of young trees, flowering in potted plants and orchard trees, and fruit growth and quality; irrigation management; irrigation systems; and monitoring of tree water use.

The relationship between fruit and leaf growth was investigated in lychee (Litchi chinensis Sonn.) in a series of experiments in subtropical Australia (lat. 27degreesS). Particles were removed at flowering to encourage new leaf growth on half the branches of each tree during fruit development. Some of the trees were pruned every week to prevent all vegetative growth, to test the effect of flower removal alone without subsequent leaf growth. In other experiments, the effect of pruning 50% of the branches was studied, but the pruning was scattered across the tree, rather than on one side. The yields of pruned trees with or without leaf flushes were more than 50% of the yield of the control plots in ten out of eleven cases, indicating that new leaves on one branch did not usually compete with fruit on adjacent branches.Concentrations of starch declined from flowering to harvest, and were higher in the branches than in the leaves, twigs, trunk and roots. In contrast, the effects of pruning were generally small. Concentrations of starch in the branches were sometimes higher when leaf or fruit growth was suppressed after pruning compared with branches with new growth. There were also slightly higher concentrations of starch in branches with leafy shoots than in those carrying fruit. These results suggest that the new leaves and fruit are more dependent on current assimilation than on stored reserves. New leaves on one branch do not reduce fruit growth in adjacent branches.

Effects of photosynthetic photon flux density (PPFD) on leaf gas exchange of lychee (Litchi chinensis Sonn.) were studied in field-grown "Kwai May Pink" and "Salathiel" orchard trees and young potted "Kwai May Pink" plants during summer in subtropical Queensland (27 degrees S). Variations in PPFD were achieved by shading the trees or plants 1 h before measurement at 0800 h. In a second experiment, potted seedlings of "Kwai May Pink" were grown in a heated greenhouse in 20% of full sun (equivalent to maximum noon PPFD of 200 micromol m(-2)xs(-1)) and their growth over three flush cycles was compared with seedlings grown in full sun (1080 micromol m(-2)xs(-1)). Young potted plants of "Kwai May Pink" were also grown outdoors in artificial shade that provided 20, 40, 70 or 100% of full sun (equivalent to maximum PPFDs of 500, 900, 1400 and 2000 micromol m(-2)xs(-1)) and measured for shoot extension and leaf area development over one flush cycle. Net CO2 assimilation increased asymptotically in response to increasing PPFD in both orchard trees and young potted plants. Maximum rates of CO2 assimilation (11.9 +/- 0.5 versus 6.3 +/- 0.2 micromol CO2 m(-2) s(-1)), dark respiration (1.7 +/- 0.3 versus 0.6 +/- 0.2 micromol CO2 m(-2) s(-1)), quantum yield (0.042 +/- 0.005 versus 0.027 +/- 0.003 mol CO2 mol(-1)) and light saturation point (1155 versus 959 micromol m(-2) s(-1)) were higher in orchard trees than in young potted plants. In potted seedlings grown in a heated greenhouse, shoots and leaves exposed to full sun expanded in a sigmoidal pattern to 69 +/- 12 mm and 497 +/- 105 cm(2) for each flush, compared with 27 +/- 7 mm and 189 +/- 88 cm(2) in shaded seedlings. Shaded seedlings were smaller and had higher shoot:root ratios (3.7 versus 3.1) than seedlings grown in full sun. In the potted plants grown outdoors in 20, 40, 70 or 100% of full sun, final leaf area per shoot was 44 +/- 1, 143 +/- 3, 251 +/- 7 and 362 +/- 8 cm(2), respectively. Shoots were also shorter in plants grown in shade than in plants grown in full sun (66 +/- 5 mm versus 101 +/- 2 mm). Photosynthesis in individual leaves of lychee appeared to be saturated at about half full sun, whereas maximum leaf expansion occurred at higher PPFDs. We conclude that lychee plants can persist as seedlings on the forest floor, but require high PPFDs for optimum growth.

Summary Experiments were conducted on lychee (Litchi chinensis Sonn.) in subtropical Australia (lat. 27° –29°S) to evaluate the role of assimilates on fruit retention. All the leaves of the last flush, all the leaves of the previous flush (about eight leaves per terminal shoot), or all the old leaves were removed from trees. Medium (3–5.cm diameter) or large branches (5–10.cm diameter) were girdled and defoliated after fruit set, and fruit retention compared with ungirdled and undefoliated branches. Other branches were girdled and defoliated between anthesis and fruit harvest. Finally, 20, 50 or 80% of the flowering panicles were defruited on large trees. Defoliated trees had 35 to 45% lower yields than the controls. This was despite the treatment with all the old leaves removed having a much lower leaf area index than the other defoliation treatments (1.7 vs. 2.3 and 2.8). Leaves next to the inflorescences are more important for yield than the older leaves. Fruit retention was very low on girdled branches that had been defoliated, especially when the leaves were removed in the first 20.d after anthesis. This suggests that the yields of girdled branches were determined by the availability of assimilates soon after fruit set. In contrast, the number of fruit retained on ungirdled branches was unrelated to the number of leaves, with defoliation having no effect on yield. Fruit on these branches were supported by resources from elsewhere in the tree. Thinned trees had similar yields to those of unthinned plots (65–82.kg tree–1). Thinning apparently increased fruit retention in the remaining clusters, under a higher leaf:fruit ratio. There were large differences in the concentrations of starch in the tree, and seasonal changes, with starch declining from flowering to fruit harvest. In contrast, there were only small responses to the treatments, suggesting that the fruit were mainly dependent on current photosynthesis. Photosynthesis in the leaves behind the fruit clusters was more important than photosynthesis in the older shaded leaves.

Changes in gas exchange with leaf age and fruit growth were determined in lychee trees (Litchi chinensis Sonn.) growing in subtropical Queensland (27 degrees S). Leaves expanded in a sigmoid pattern over 50 days during spring, with net CO2 assimilation (A) increasing from -4.1 +/- 0.9 to 8.3 +/- 0.5 micromol m-2 s-1 as the leaves changed from soft and red, to soft and light green, to hard and dark green. Over the same period, dark respiration (Rd) decreased from 5.0 +/- 0.8 to 2.0 +/- 0.1 micromol CO2 m-2 s-1. Net CO2 assimilation was above zero about 30 days after leaf emergence or when the leaves were half fully expanded. Chlorophyll concentrations increased from 0.7 +/- 0.2 mg g-1 in young red leaves to 10.3 +/- 0.7 mg g-1 in dark green leaves, along with stomatal conductance (gs, from 0.16 +/- 0.09 to 0.47 +/- 0.17 mol H2O m-2 s-1). Fruit growth was sigmoidal, with maximum values of fresh mass (29 g), dry mass (6 g) and fruit surface area (39 cm2) occurring 97 to 115 days after fruit set. Fruit CO2 exchange in the light (Rl) and dark (Rd) decreased from fruit set to fruit maturity, whether expressed on a surface area (10 to 3 micromol CO2 m-2 s-1 and 20 to 3 micromol CO2 m-2 s-1, respectively) or on a dry mass basis (24 to 2 nmol CO2 g-1 s-1 and 33 to 2 nmol CO2 g-1 s-1, respectively). Photosynthesis never exceeded respiration, however, the difference between Rl and Rd was greatest in young green fruit (4 to 8 micromol CO2 m-2 s-1). About 90% of the carbon required for fruit growth was accounted for in the dry matter of the fruit, with the remainder required for respiration. Fruit photosynthesis contributed about 3% of the total carbon requirement of the fruit over the season. Fruit growth was mainly dependent on CO2 assimilation in recently expanded dark green leaves.

We investigated the effects of the timing of shoot elongation on the flowering of lychee (Litchi chinensis Sonn.) in eastern Australia. Trees of cv. Kwai May Pink growing in Alstonville (lat. 28.9° S) were pruned during spring and summer, and subsequent shoot elongation was measured until the following spring. New shoots grew by discrete flushes, with the trees initiating 3, 2, or 1 vegetative shoots prior to winter, according to the pruning sequence. Shoots were vegetative when the mean temperature during early flush development was above 17-19°C, and floral at lower temperatures. Trees with successive flushes commencing in February (late summer) and June (early winter) were more likely to flower than trees with flushes commencing in April and August, because the weather conditions in June were cooler than those in August and more likely to favour induction. The importance of cool weather conditions during early flush development for floral determination was not significantly affected by the number of vegetative flushes to develop between pruning and winter. Having shown that the phase of recurrent flushing affects flowering, we sought to model the process in order to recognise reproductive and non-reproductive cycles along Australia's north-eastern seaboard, and to develop a management strategy for the promotion of flowering. From the results of the Alstonville pruning trial, the interval between successive flushes was regressed against the mean product of daily irradiation and mean daily temperature (°C.MJ/[m2.day]) during the interval. The regression was used in conjunction with long-term weather records to estimate the flush commencement dates required for the completion of 1 or 2 vegetative flushes by the winter solstice at different latitudes. The earliest date for the completion of 1 flush ranged from 16 February in northern New South Wales (lat. 30° S) to 13 March in northern Queensland (lat. 17° S). To test the model, a pruning trial was conducted near Mareeba (lat. 17° S). Trees pruned on 10 February, estimated to produce ≈ 1.5 flushes prior to winter (i.e. flushes in late autumn and early spring, but not in winter), flowered poorly and had low yields. In contrast, trees pruned on 11 March, estimated to produce 1 vegetative flush by winter, had good flowering and yields. Thus, strategic pruning after harvest can be used to manipulate flushing times, so that new, potentially flowering shoots emerge in winter. Cool temperatures are still required for successful flowering, and we provide estimates of the likelihood of such weather in the major growing areas by calculating the annual number of days with a mean temperature <20°C. For Cairns (lat. 16.9° S) the number of such days varied from 0 to 39 from 1888 to 1993, which is consistent with the irregular flowering of lychee in coastal northern Queensland. Our work is the first demonstration for any species that the phase of recurrent flushing affects flowering, and emphasises the interplay between a plant's endogenous developmental cycle and seasonal variations in weather.

Shoot growth, chlorophyll concentrations, gas exchange and starch concentrations were studied in lychee (Litchi chinensis Sonn.) seedlings of cultivar "Wai Chee" grown in a heated greenhouse at Nambour in subtropical Australia (27 degrees S). We also examined the effects of shoot defoliation and root pruning on leaf expansion. Shoot growth showed a rhythmic cycle under constant greenhouse conditions, with a mean duration of flushing of 20 days and an interval of 10 days over three cycles. Shoots and leaves expanded in a sigmoidal pattern to about 80 mm and 500 cm(2), respectively, for each flush. Starch concentrations of the lower stem and roots decreased as the young red leaves expanded, and increased as the fully expanded leaves turned dark green. Chlorophyll concentrations and net CO(2) assimilation rate were highest in the fully expanded dark green leaves. Removing 50% of the area of each fully expanded leaf had little effect on the expansion of younger leaves, but total biomass of defoliated plants was only 60% of that of controls. In contrast, removing half the roots just before bud swelling reduced final leaf area by 80%. We conclude that the young shoot has relatively low rates of photoassimilation until the leaves are fully expanded and dark green, and depends on assimilates from elsewhere in the plant. During leaf expansion, translocation of assimilates to the shoot occurred at the expense of the roots.

In glasshouse experiments, high temperatures increased vegetative growth in the tropical rambutan (Nephelium lappaceum L. seedlings of cv. Rapiah). In absolute terms, there was generally a greater response to night temperature (day/night temperatures of 32 degrees/14 degrees C vs. 32 degrees/28 degrees C) than to day temperature (22 degrees/14 degrees C vs. 32 degrees/14 degrees C), and better growth at 32 degrees/28 degrees C than at 32 degrees/22 degrees C. The effects of temperature on nutrient concentrations were small, whereas average leaf water potential (Psi(L)) during the day was -1.5 MPa at 32 degrees/28 degrees C, 0.1 to 0.4 MPa higher with nights of 14 degrees or 22 degrees C, and 0.7 MPa higher at 22 degrees/14 degrees C. Average net CO2 assimilation rate (A) was 5.3 mu mol m(-2)s(-1) at 32 degrees/22 degrees and 32 degrees/28 degrees C, 50% lower at 32 degrees/14 degrees C and 80% lower at 22 degrees/14 degrees C. When seedlings of cv. Rapiah were grown in water baths, the two critical root temperatures at which 90% of maximum plant weight occurred were similar for leaves and stems (about 24 degrees to 30 degrees C), but lower for roots (19 degrees to 25 degrees C). There was only a small effect of temperature on the concentration of most nutrients,and on average day time Psi(L), whereas average A was 4.5 mu mol m(-2)s(-1) at 28 degrees C, 30% lower at 20 degrees C, and 80% lower at 150 and 38 degrees C. These experiments show that rambutan growth was strongly reduced when night or root temperatures fell to 14 degrees or 15 degrees C. The main effect was through lower CO2 assimilation, whereas the changes in water and nutrient status were relatively small. Areas where night or root temperatures remain at or below 14 degrees C for prolonged periods should be avoided for rambutan production.

The roles of current CO2 assimilation and stored carbohydrates on fruit retention in lychee (Litchi chinensis Sonn.) were investigated. In 12 year old 'Tai So' trees growing at Burgershall in subtropical South Africa (lat. 25 degrees S), terminal branches were cinctured (girdled) 0.5 or 1.0 m from the fruit cluster about 2-4 weeks after anthesis in October to isolate the fruit from the rest of the tree. Each branch had 0, 5, 10, 20 or 30 leaves, and 0, 5, 10, 20 or 30 fruit. In a separate experiment, branches were cinctured 0.5 or 1.5 m from the fruit cluster in October, while uncinctured branches acted as controls. At Nambour in subtropical Australia (lat. 27 degrees S), branches of ten year old 'Souey Tung' were cinctured in October after fruit set about 1.2 m from the fruit cluster, while other branches were cinctured and thinned to five leaves or five fruit per fruit cluster or left uncinctured and unthinned. In other experiments, seven year old trees of cv. Wai Chee and ten year old trees of cv. Kwai May Pink were cinctured on the trunk in November or left uncinctured. The number of fruit retained per panicle, net CO2 assimilation, yield and concentrations of starch in the leaves and stem were determined. In South Africa, the greatest number of fruit per panicle at harvest (8.6) occurred with 30 leaves and 30 fruit at the start of sampling, but a different response was given when the number of fruit retained was expressed as a proportion of that soon after fruit set. Relative fruit retention was below 5% in branches with no leaves and 50-60% in branches with six leaves per fruit. In Australia, about a quarter of the fruit were retained at harvest in control and cinctured branches compared with more than two-thirds after fruit thinning and only one-tenth after leaf thinning. Starch generally accumulated in the stems after fruit were removed, whereas CO2 assimilation was greatest after leaf removal and least with fruit removal. There was double the relative fruit retention with cinctures at 0.5 m (25%) compared with controls (14%), and three times as many with cinctures at 1.5 m (38%), and a 35% increase in yield when whole trees were cinctured. These results suggest that lychee fruit appear to be mainly dependent on current CO2 assimilation. Cincturing increased yields presumably by redirecting assimilates to the developing crop.

The impact of soil water deficits and non-hydraulic root signals on the expansion, functioning and water status of leaves and the opening of flowers of passionfruit was studied in a series of pot experiments. Hydraulic and non-hydraulic signals were separated by withholding water from half the root system.The leaves of well-watered plants expanded in a sigmoid pattern to about 65 cm(2) over 15 to 18 days. Drying the whole root system stopped leaf expansion after 6 days, but did not change the pattern of leaf growth. Growth resumed after rewatering but the final leaf size was halved. As leaf growth slowed, the net photosynthesis, P-n, of mature leaves fell from 11 +/- 1 mu mol CO2 m(-2) s(-1) to less than zero as the leaves wilted. Leaf water potential, psi(1), of mature leaves at midday ranged from -0.9 MPa in well-watered plants to -3.1 to -3.7 MPa in wilted plants. After rewatering, psi(1) returned to -0.9 MPa within 1 day, but P-n took 3 days to return to control levels. A midday psi(1) of -1.5 MPa was associated with a 50% reduction in relative leaf expansion and net photosynthesis.Drying half of the root system reduced leaf expansion by 26%, compared with well-watered plants, and water use by 21 to 27%, without influencing psi(1) or P-n. Plants with half the root system dry for 13 days flowered earlier than well-watered plants but had the same number of open flowers 1 month after treatments ended, Non-hydraulic root signals affect leaf expansion and flowering in passionfruit.

The effect of temperature was investigated on the vegetative growth and flowering of nine coffee cultivars (Catuai Rojo, Catuai, Caturra Amarillo, Caturra Rojo, Catimor, BMK, SL6, K7 and LB) grown in pots under glass. High day/night temperatures (33 degrees/28 degrees compared with 18 degrees/13 degrees, 23 degrees/18 degrees and 28 degrees/23 degrees C) accelerated stem extension and node production. Growth was greatest in cvs K7 and SL6 and lowest in cv. Caturra Rojo. Prolonged exposure to high temperatures of 33 degrees/28 degrees C accelerated leaf loss and induced a general decline in tree health. All cultivars showed rapid initial growth during summer and autumn, and slower growth during winter and spring under short days (<13 h) and low irradiances (<6.8 MJ m(-2) d(-1)). Growth did not recover in spring and summer at the end of the experiment. Inflorescences were initiated mainly from April to September under photoperiods <12 h. More floral buds initiated at 23 degrees/18 degrees C and 18 degrees/13 degrees C than at 28 degrees/23 degrees C and no floral initiation occurred at 33 degrees/28 degrees C. Inflorescence development took 4-6 weeks at 28 degrees/23 degrees compared with 8-10 weeks at 23 degrees/18 degrees and 12-14 weeks at 18 degrees/13 degrees C. High temperatures also induced floral malformations. Cvs Catuai Rojo, Caturra Rojo and Caturra Amarillo had most inflorescences per node and cvs K7, BMK and LB fewest. Temperatures of 33 degrees/28 degrees C during summer will ensure maximum vegetative growth and potential number of flowering nodes. Temperatures of 23 degrees/18 degrees C during winter will ensure healthy and synchronized floral bud development and maximize the number of inflorescences per node.

Flowering in lychee (Litchi chinesis Sonn.) is promoted by low temperatures, but the critical level and duration of chilling required for successful induction are not known. The effects of maxima/minima of 15 degrees/5 degrees, 20 degrees/5 degrees, 20 degrees/10 degrees, 20 degrees/15 degrees, 25 degrees/10 degrees, 25 degrees/15 degrees, 25 degrees/20 degrees or 30 degrees/20 degrees C on vegetative growth and flowering of cvs Kwai May Pink and Casino were investigated. In a second experiment, plants of cv. Wai Chee were given 0, 2, 4, 6, 8, 10 or 31 weeks of induction at 15 degrees C before transfer to non-inductive conditions at 30 degrees/20 degrees C. In a third experiment, cv. Wai Chee was grown at 15 degrees C and given 0, 1, 2 or 8 h above 20 degrees C (0, 2, 4 or 15 h above 15 degrees C) per 24 h. In Experiment 1 with cv. Kwai May Pink, there was vegetative growth at 25 degrees/20 degrees C and 30 degrees/20 degrees C, a mixture of vegetative growth and flowering at 25 degrees/10 degrees and 25 degrees/15 degrees C, and flowering at lower temperatures. Cv. Casino responded similarly, except that there was no growth or flowering at 25 degrees/10 degrees C and 25 degrees/15 degrees C. For both cultivars, nearly all branches flowered at 20 degrees/15 degrees C or lower. Flowering in 'Wai Chee' occurred with four weeks at 15 degrees C before transfer to warmer temperatures and was greatest with six weeks. There was also an effect of treatment on the type of inflorescence, with fewer leaves after ten weeks of induction. Plants of 'Wai Chee' exposed to 2 h above 20 degrees C per day were mainly floral, whereas those given eight or more hours were vegetative. It was concluded that flowering in lychee was best after ten weeks at 15 degrees C, while periods of 8 h or more per 24 h above 20 degrees C were detrimental.