Progress 10/01/10 to 09/30/11
Outputs
Progress Report Objectives (from AD-416) 1) Optimize chlorate-induced flowering & fruit production in longan; 2) Determine the long-term effect of chlorate application on longan fruit quality; 3) Determine floral induction for "Kaimana" Lychee; 4) Evaluate new lychee cultivars for Hawaii; and 5) Stimulate off-season flowering of lychee. Approach (from AD-416) 1) Foliar applications of alternative chemicals to chlorate will be evaluated & fruit thinning experiment will be conducted; 2) Soil chlorate levels, plant nutrition, flowering & fruit quality will be evaluated on longan tree after repeated application of chlorate; 3) Artificial cool temperatures will be used to determine floral induction for "Kaimana" lychee; 4) Molecular markers will be used to identify lychee that flower & fruit in Hawaii; and 5) Grafting experiments will be used to transmit floral stimuli from longan to lychee and between lychee cultivars with different floral initiation requirements. (Documents Trust agreement with UH Hilo. 425 log 31540). Formerly 5320-21000-009-07T (09/2008). This agreement was established in support of Objective 3 of the parent project, the goal being to characterize and evaluate tropical fruit genetic resources for priority traits, such as flowering and fruiting. This is the final report for the project 5320-21000-012-01T which will terminate in August, 2011. Chlorate treatments in longan commonly induce flowering in 90 to 100% of terminals which require fruit thinning when fruits are 6-12 mm in diameter. Fruit thinning is a labor intensive process consisting of removal of 1/2 to 2/3 of each panicle. Sequential applications of foliar fertilization during fruit development and hand thinning of fruiting panicles on two longan cultivars, �Egami� and �Biew Kiew� were compared. In the heavier bearing �Egami� cultivar, the incidence of fruit cracking and unmarketable under-sized fruits was greater in the foliar fertilized trees compared to hand thinned tree. Postharvest quality including aril firmness and disease incidence was also more severely affected in the fruits from the foliar fertilized trees compared to the hand thinned trees. The foliar fertilization treatment was comparable to hand thinned fruiting panicles in the lesser bearing �Biew Kiew� cultivar, and fruit quality was retained even after storage for 14 days. Fruits from the chlorate treated trees were also provided to researchers for additional post-harvest packaging treatments to determine the best packaging material on longan quality. Flowering locus T (FT) is a gene involved in flowering, originally identified in model system Arabidopsis. Equated to the classic physiological flowering signal florigen; the FT protein is produced in leaves and translocated into the meristem where it initiates the transition from vegetative to floral growth. Using degenerative PCR primers we have isolated three full length FT orthologs from longan and the 5� end of four FT orthologs from lychee. From Southern blot analysis, we estimate that there may be five FT genes in longan and four or five genes in lychee. Semi-quantitative polymerase chain reaction (PCR) suggest that the FT genes in longan are less abundant in leaves from chlorate treated trees 12 to 24 days after chlorate treatments compared with non-treated trees. Temperature regulation has not been determined due to low floral induction conditions present in Hawaii during the winter of 2010 to 2011. The lead scientist monitored progress through site visitations, individual meetings with growers, and presentations at the Hawaii Tropical Fruit Growers annual meeting.
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Progress 10/01/09 to 09/30/10
Outputs
Progress Report Objectives (from AD-416) 1) Optimize chlorate-induced flowering & fruit production in longan; 2) Determine the long-term effect of chlorate application on longan fruit quality; 3) Determine floral induction for "Kaimana" Lychee; 4) Evaluate new lychee cultivars for Hawaii; and 5) Stimulate off-season flowering of lychee. Approach (from AD-416) 1) Foliar applications of alternative chemicals to chlorate will be evaluated & fruit thinning experiment will be conducted; 2) Soil chlorate levels, plant nutrition, flowering & fruit quality will be evaluated on longan tree after repeated application of chlorate; 3) Artificial cool temperatures will be used to determine floral induction for "Kaimana" lychee; 4) Molecular markers will be used to identify lychee that flower & fruit in Hawaii; and 5) Grafting experiments will be used to transmit floral stimuli from longan to lychee and between lychee cultivars with different floral initiation requirements. (Documents Trust agreement with UH Hilo. 425 log 31540). Formerly 5320-21000-009-07T (09/2008). This agreement was established in support of Objective 3 of the in-house project, the goal being to characterize and evaluate tropical fruit genetic resources for priority traits, such as flowering and fruiting. Pruning and foliar fertilizer management strategies for synchronized flowering and fruiting are being evaluated at 5 locations varying in elevation and climacteric conditions on the Big Island of Hawaii. Preliminary results suggest that irrigation after cool floral inducting temperatures substantially increases the flowering and fruit size in areas with reduced rainfall. Comparison of the recommended thinning protocol of removing 2/3 of the flowering panicle and a foliar fertilizer schedule to increase fruit size is being evaluated. We have confirmed results which suggest that foliar fertilizer and hand thinning result in fruits of similar size and TSS (total soluble sugar). Fruits from this study were provided for the post- harvest quality study which showed that longan trees treated with excess foliar fertilizer results in diminished post-harvest quality and increased disease incidence. The ADODR monitored progress through site visitations, individual meetings with growers, and presentations at the Hawaii Tropical Fruit Growers annual meeting.
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Progress 10/01/08 to 09/30/09
Outputs
Progress Report Objectives (from AD-416) 1) Optimize chlorate-induced flowering & fruit production in longan; 2) Determine the long-term effect of chlorate application on longan fruit quality; 3) Determine floral induction for "Kaimana" Lychee; 4) Evaluate new lychee cultivars for Hawaii; and 5) Stimulate off-season flowering of lychee. Approach (from AD-416) 1) Foliar applications of alternative chemicals to chlorate will be evaluated & fruit thinning experiment will be conducted; 2) Soil chlorate levels, plant nutrition, flowering & fruit quality will be evaluated on longan tree after repeated application of chlorate; 3) Artificial cool temperatures will be used to determine floral induction for "Kaimana" lychee; 4) Molecular markers will be used to identify lychee that flower & fruit in Hawaii; and 5) Grafting experiments will be used to transmit floral stimuli from longan to lychee and between lychee cultivars with different floral initiation requirements. (Documents Trust agreement with UH Hilo. 425 log 31540). Formerly 5320-21000-009-07T (09/2008). Significant Activities that Support Special Target Populations Comparison of the recommended thinning protocol of removing 2/3 of the flowering panicle and a foliar fertilizer schedule to increase fruit size is being evaluated. Preliminary results suggest that foliar fertilizer and hand thinning result in fruits of similar size and TSS (total soluble sugar). Fruits from this study were provided for the post-harvest quality study which showed that longan trees treated with excess foliar fertilizer results in diminished post-harvest quality and increased disease incidence. Treatment of �Biew Kiew� longan trees with low (50g) and high (300g) KClO3 levels were evaluated over a three year period. Lower chlorate treatments on trees not previously treated with chlorate resulted in flowering that ranged from 48% to 93% for year 1, 6% to 22% for year 2 and 34% to 71% for year 3. Higher chlorate treatments on trees not previously treated with chlorate resulted in flowering that ranged from 78% to 100% for year 1, 100% for year 2 and 52% to 91% for year 3. These results suggest that 50g KClO3 is too low a level to give consistent flowering and fruit production; un-thinned fruit size is not significantly different compared to thinned fruit from trees treated with 300g KClO3. The diminished flowering response was not observed until the 3rd application of chlorate at the higher rate of 300g KClO3 but a lower response was observed in year 2 with the lower chlorate treatment. A study has been initiated to synchronize the vegetative growth of the longan trees after fruit harvest to determine if the number of flushes prior to chlorate treatments will affect the flowering response. Preliminary experiments to determine the cold requirements for �Kaimana� flowering were conducted on �Kaimana� potted plants moved to the Volcano experiment station (4000 ft elev) and exposed to cold temperatures for 4, 5 and 6 weeks. Exposure to average daily air temperatures of 56.69 �F and soil temperatures of 50.38�F for all exposure times resulted in 100% flowering of �Kaimana� while untreated control plants kept in Hilo did not flower, suggesting that potted lychee plants are suitable to determine the temperature and duration required for floral induction of �Kaimana�. Preliminary experiments on exposure of �Kaimana� to day temperatures of 72�F and night temperatures of 60�F or 65�F for 2 weeks did not result in lychee flowering. Other growth chamber experiments to determine the cold requirements of �Kaimana� floral induction are currently being evaluated. The ADODR monitored progress through site visitations, individual meetings with growers and presentations at the Hawaii Tropical Fruit Growers annual meeting.
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Progress 10/01/07 to 09/30/08
Outputs
Progress Report Objectives (from AD-416) 1) Optimize chlorate-induced flowering & fruit production in longan; 2) Determine the long-term effect of chlorate application on longan fruit quality; 3) Determine floral induction for "Kaimana" Lychee; 4) Evaluate new lychee cultivars for Hawaii; and 5) Stimulate off-season flowering of lychee. Approach (from AD-416) 1) Foliar applications of alternative chemicals to chlorate will be evaluated & fruit thinning experiment will be conducted; 2) Soil chlorate levels, plant nutrition, flowering & fruit quality will be evaluated on longan tree after repeated application of chlorate; 3) Artificial cool temperatures will be used to determine floral induction for 'Kaimana' lychee; 4) Molecular markers will be used to identify lychee that flower & fruit in Hawaii; and 5) Grafting experiments will be used to transmit floral stimuli from longan to lychee and between lychee cultivars with different floral initiation requirements. (Documents Trust agreement with UH Hilo. 425 log 31540) Significant Activities that Support Special Target Populations Treatment of longan with potassium chlorate often results in 100% flowering terminals which results in smaller fruits. We have conducted experiments to determine the optimal amount of the panicle that must be hand thinned to maximize fruit size and total harvestable fruits per tree. �Biew Kiew� trees were treated with 250 g of potassium chlorate. When fruit reached �pea-size�, longan panicles were thinned to remove 0%, 25%, 50% or 75% (10 panicles per treatment) of the developing fruit. The number of fruits per panicle was recorded during treatment implementation. The remaining panicles were thinned to remove 2/3 of the fruits. No significant difference was detected in the fruit size and weight for the fruit thinning panicles suggesting the overall fruit load per tree may be more important than thinning individual panicles. Experiments are currently being implemented to determine if foliar fertilizers can replace the labor intensive hand-thinning procedure. Harvested fruits from foliar and hand thinned trees will be provided to another project which will be evaluating postharvest quality during storage. In Hawaii, consistent lychee production is achieved through management practices that limit high nitrogen content and new vegetative flushes during the time of year when cooler temperatures induce flowering. We have adapted the pruning and foliar management protocol developed at the TPGRM unit and expanded it to commercial 'Kaimana' fields located in the rocky soils of Kona and deep silty clay loam soils in Hamakua. The pruning and foliar fertilizer application successfully resulted in flowering and fruiting of lychee in Kona similar to the trees in the TGRMU lychee orchard. However, the pruned and foliar fertilized trees resulted in vigorous vegetative growth and reduced flowering and fruit production in the Hamakua orchard. The best treatments for this location were non-pruned control trees and non-pruned trees treated with foliar fertilizer only. These experiments will be repeated at the various locations for the next lychee season. In addition, plants have been propagated to determine the temperature requirements for floral induction of �Kaimana� lychee through growth chamber experiments. Application of foliar fertilizer instead of ground applied granular fertilizer to producing �Kaimana� trees after pruning provided consistent levels of nutrients to the trees, reduced reliance on fertilizer availability dependent upon rainfall and limited the amount of residual fertilizer held in the soil. An average production of about 100 lb per tree per year occurred over two seasons in 8-9 year old trees when pruning and foliar fertilizer was used to synchronize and condition 'Kaimana' lychee trees at the Waiakea Station. This pruning and foliar management protocol at Kona and Hamakua orchards resulted in successful flowering and fruiting in Kona similar to trees at Waiakea. However, treatments in Hamakua resulted in vigorous vegetative growth and reduced flowering and fruit production. The pruning/foliar treatment was most promising in orchards with rocky soils and little water holding and nutrient retention capacity.
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Progress 10/01/06 to 09/30/07
Outputs
Progress Report Objectives (from AD-416) 1) Optimize chlorate-induced flowering & fruit production in longan; 2) Determine the long-term effect of chlorate application on longan fruit quality; 3) Determine floral induction for "Kaimana" Lychee; 4) Evaluate new lychee cultivars for Hawaii; and 5) Stimulate off-season flowering of lychee. Approach (from AD-416) 1) Foliar applications of alternative chemicals to chlorate will be evaluated & fruit thinning experiment will be conducted; 2) Soil chlorate levels, plant nutrition, flowering & fruit quality will be evaluated on longan tree after repeated application of chlorate; 3) Artificial cool temperatures will be used to determine floral induction for "Kaimana" lychee; 4) Molecular markers will be used to identify lychee that flower & fruit in Hawaii; and 5) Grafting experiments will be used to transmit floral stimuli from longan to lychee and between lychee cultivars with different floral initiation requirements. (Documents Trust agreement with UH Hilo. 425 log 31540) Significant Activities that Support Special Target Populations This report serves to document research conducted under a trust agreement between ARS and the University of Hawaii, Office of Research Services. Additional details of research can be found in the report for the parent CRIS 5320-21000-009-00D 'Assuring long-term preservation of tropical crops via genetic resource management. No significant research has been made for this project since funding was not received until August 2007.
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