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【Objective】The production mode of Hainan longan can be divided into natural flowering on-season longan and off-season longan induced by potassium chlorate. Reasonable fruit loading is extremely important to maintain tree vigor and avoid alternate bearing results. The fruit loading regulation modes in the production of on-season and off-season longan are greatly different. The fruit setting amount of on-season longan is great, which seriously affects the tree vigor and fruit quality, while off-season longan fruit abscission before harvest is a common phenomenon, which seriously affects the yield. Therefore, fruit thinning of on-season longan and fruit preserving of off-season longan are equally important in the production.【Method】The main cultivar Shixia longan was used as the test material, and two tests including fruit thinning of on-season longan and fruit preserving of off-season long were set. The fruit thinning effect was studied by treating the longan ears with different fruit thinning agents, and the fruit preserving effect was studied with the treatment of different fruit preserving agents after artificially induced fruit abscission of off-season longan.【Result】By tracking and monitoring the fruit abscission rate and the separation force of the pedicel abscission layer, it was found that IAA and DMTU treatments delayed fruit abscission process for 2 days, 2, 4-D and NAA treatments delayed the fruit abscission process for 3 days in off-season longan, but neither of them could prevent fruit abscission. Treatment of fruit substituted by IAA completely inhibited the pedicel separation in off-season longan. Girdling treatment could induce 100% of on-season longan fruit abscission within 6 days; different concentrations of ethephon, paraquat and 100 g/L urea treatment could induce 11.88%-53.05%, 29.23% and 35.43% of fruit abscission respectively within 10 days. After 10 days, there was very little fruit abscission under urea treatment, while other treatments showed sustained fruit abscission.【Conclusion】The results show that carbohydrate stress, paraquat, ethephon and urea treatment can induce the abscission layer separation of longan pedicel, and these agents have a fruit thinning effect on on-season longan. IAA, 2, 4-D, NAA, DMTU can delay the abscission layer separation of fruit pedicel, which can effectively delay the abscission of off-season longan before harvest. All the treatments that can enhance the IAA signal can play a role in fruit preserving, while all the treatments that reduce the synthesis and transport of IAA and the treatments that enhance the ethylene signal have effects on fruit thinning. Therefore, in terms of production, it is suggested that measures should be taken to thin the fruit of on-season longan as early as possible to reduce the consumption of carbohydrates and then ensure the quality and yield of the fruits. In the middle fruiting period of off-season longan, certain fruit preserving measures should be taken to ensure the accumulation of IAA in the fruit to avoid the abscission of fruits.

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An experiment with girdling applied on the main stem and fruit branch during the early or flourishing stage of flowering and boll-setting was conducted to investigate the effects of different girdling treatments on the growth, yield and water use efficiency (WUE) of cotton. The results showed that compared with the control (CK), leaf area index (LAI) of girdling treatments reduced significantly and the maximum LAI of girdled cotton occurred 5-15 days in advance. Girdling reduced the shedding rate of squares and bolls significantly, and the shedding rate of squares and bolls with girdling applied on the main stem at the flourishing stage was 15. 8% lower than that of CK. In contrast with CK, the seed-cotton yield and WUE increased by 24. 4% and 26. 7% with girdling applied on the main stem at the flourishing stage, and increased by 13. 9% and 16. 7% with girdling applied on the fruit branch at the early stage, respectively. However, the girdling on the fruit branch at the flourishing stage improved the seed-cotton yield and WUE insignificantly. The seed-cotton yield with girdling on the main stem at the early stage had not significant difference and its WUE reduced slightly compared with CK. It has been concluded that the girdling applied on the main stem at the flourishing stage of flowering and boll-setting could effectively reduce the abscission rate of squares and bolls, improve yield and WUE significantly, and realize the effective unity of high production and water-saving. [ABSTRACT FROM AUTHOR]

To explore the nutrient source and supply-demand relationship of the female cone deve-lopment and new shoot growth of Pinus koraiensis, reproductive mother branches were experimentally girdled, defoliated, and under the combination of both treatments. The effects of different treatments on the female cones development, branch growth and the content of carbohydrate (NSC), nitrogen (N) and phosphorus (P) in different tissues and organs were measured. The results showed that girdling significantly affected female cone development, new shoot growth, and the contents of NSC, N and P in different tissues and organs, while defoliation treatment had limited effect. The NSC content in the mother branch xylem and phloem after girdling were significantly lower than that of the control (CK, ungirdling+0% defoliation), and decreased significantly with the increases of the degree of defoliation. The NSC content in mother branch xylem and phloem of girdling+100% defoliation was 59.0% and 64.8% lower than that of CK, respectively. The deficiency of NSC resulted in the death of mother branches and new shoots and the abortion of female cone. Under girdling treatment, the contents of N and P in xylem and phloem of mother branches of 0%, 50% and 100% defoliation treatment were significantly higher than that of CK. The contents of N and P in xylem of mother branches were 17.3%, 18.2% and 24.3% and 17.9%, 7.1% and 3.6% higher than those of CK, respectively. The contents of N and P in phloem of mother branches was 39.3%, 35.2% and 48.9% and 31.0%, 28.2% and 14.8% higher than those of CK, respectively. The female cone development and new shoot growth of P. koraiensis consumed a large amount of NSC, N and P. The carbohydrates and mineral nutrients manufactured or stored in the mother branches could not meet the needs of female cone development and new shoot growth, and thus they need to be imported from other tissues.