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United States Department of Agriculture

Agricultural Research Service

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Research Project: IMPROVING FLOWERING OF LONGAN AND LYCHEE TREES IN HAWAII

Location: Tropical Plant Genetic Resources and Disease Research

2010 Annual Report


1a.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.


1b.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).


3.Progress Report

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.


Last Modified: 7/31/2014
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