A study on the techniques for producing off-season wax apples in Zhangzhou

ZHENG Jiaxie;ZHOU Hongling;ZHANG Shaoping;ZHENG Yunyun;Institute of Subtropical Agriculture, Fujian Academy of Agricultural Sciences;

Wax apple;;Producing off-season;;Girdling;;Shading;;Root pruning;;Flower forcing agent

【Objective】Organophosphorus pesticides, such as chlorpyrifos and fenitrothion, are commonly used as flower forcing agent for wax apples [Syzygium sarnarangense(Bi.) Merr. et Perry]. A pollution-free flower forcing agent replacing organophosphorus pesticides for producing off-season wax appleswas studied in Zhangzhou. The main technique of flower forcing in wax apples includes retardation of vegetative growth by pruning, girdling, root pruning, field flooding, field drying, shading, heavy pruning alone, or combination of these methods, followed by the treatment with flower forcing agent.【Methods】6-year-old trees of wax apple‘Pink'were used as the experimental materials for producing off-season wax apple.The flower forcing procedures included girdling and 90% shading for 45 days after the secondary shoots matured after light pruning in early March, followed by root pruning and spraying flower forcing agent about 15 days later. To compare with chlorpyrifos, the commonly used flower forcing agent, a self-prepared pollution-free MP(a foliage fertilizer)was used as flower forcing agent based on previous screening test for effective forcing agent. The experiment included 12 treatments: treatment 1, girdling and shading plus pruning and chlorpyrifos treatment, treatment 2, girdling and shading plus chlorpyrifos treatment,treatment 3, girdling plus chlorpyrifos treatment, treatment 4, girdling and shading plus pruning and MP treatment, treatment 5, girdling and shading plus chlorpyrifos treatment, treatment 6, girdling plus chlorpyrifos treatment, treatment 7, girdling and shading plus pruning, treatment 8, girdling and shading, treatment 9, girdling and pruning, treatment 10, chlorpyrifos treatment alone, treatment 11, MP treatment alone, and treatment 12, control with no girdling, shading, pruning or chemical treatment. A randomizedblock design with three replications(three trees) was used. The experiment was repeated twice to test the repeatability of the results. The phenophases of blooming and fruiting were recorded and the number of flower clusters, fruit yield, fruit mass and soluble solid content were investigated at different stages. The flowering and fruiting characteristics were compared between MP and chlorpyrifos as the flower forcing agents for producing off-season wax apples.【Results】The treatments had 1 to 5 day difference in time of flower bud appearance after spraying the forcing agents. The flower buds began to appear in the mid to late August; the beginning of blooming occurred in the mid September; the full blooming was in the late September; the beginning of fruit set took place in the early October; fruit harvest initiated in the early December, and fruit harvest ended in the early February next year, when the flower forcing agents were sprayed in the early August. The results of the repeated experiment showed that there were 213.0 flower clusters in average in each plant in treatment 1(girdling and shading plus pruning and chlorpyrifos treatment). The number was 224.5 in treatment 4(girdling and shading plus pruning and MP), 113.5 in treatment 5, 96.0 in treatment 2, 18.0 in treatment 3, 15.0 in treatment 6, 8.5 in treatment 7 and 5.5 in treatment 8,and there was no flowers in treatments 9, 10 and 11 and in the control. The number of flower clusters per plant in treatment 1 or treatment 4 was significantly larger than those in the other treatments. However, there was no significant difference between treatment 1 and treatment 4. The average fruit yield per plant was 73.0 kg in treatment 1 and 77.8 kg in treatment 4, both being significantly higher than those of the other treatments. There was no significant difference in fruit productivity between treatment 1 and treatment 4. The different treatments had little effect on fruit mass and soluble solid content in the fruit.The results indicated that flower forcing in treatment 1 and treatment 4 was very effective and that chlorpyrifos can be replaced by MP as the flower forcing agent for producing off-season wax apples.【Conclusion】Chorpyrifos and MP resulted in comparable effect in forcing flowering in wax apple. Therefore it is possible to use the self-prepared pollution-free MP instead of organophosphorus pesticides as the flower forcing agent for producing off-season wax apples. The flower forcing procedures are girdling and 90%shading for 45 days started when the secondary shoots mature after light pruning in the early March, followed by root pruning and spraying MP 15 days later.