ABSTRACT

This study was carried out on ?Xuong Com vang? longan 4-5 year old trees grafted on ?Da Bo? longan rootstocks at Chau Thanh district, Dong Thap province from 8/2007-6/2008. The experiments were the factorial experiments with two factors which were arranged in randomized completely block design, 5 replications, each replication equal to one tree. The first factors was dosages of potassium chlorate i.e. 0, 8, 16 and 24 g per meter of canopy diameter applying by collar drenching; the second one was application with and without 3-5 mm main branch cincturing. The results showed that the treatment of potassium chlorate at 24 g/m canopy diameter obtained the highest ratio of flowering (72.4%). Cincturing of main branch in 3-5 mm increased ratio of flowering about 36%. Treatment of potassium chlorate at 24 g/m canopy diameter combination with cincturing induced early-season flowering 30 days earlier than that of control treatment. Treating KClO3 caused decreasing level of total nitrogen in leaf but increased the rate of C/N on flowering period. The ratio of flowering correlated negatively with total nitrogen in leaf (r=-0,83**) but positively correlated with ratio of C/N (r=0.82).

Keywords: Cincturing, off-season, Xuong Com Vang, potassium chlorate

Title: Effect of potassium chlorate treatment and cincturing application on off-season flowering and yield of ?Xuong Com Vang? Longan (Dimocarpus longan Lour.) in Chau Thanh district, Dong Thap province

ToM t?T

Thi nghi?m d??c th?c hi?n tren cay nh?n Xu?ng C?m Vang 4-5 nam tu?i ghep tren g?c nh?n tieu Da Bo t?i huy?n Chau Thanh, t?nh D?ng Thap t? thang 8/2007-6/2008. Thi nghi?m th?a s? hai nhan t? d??c b? tri theo th? th?c kh?i hoan toan ng?u nhien, v?i 8 nghi?m th?c 5 l?n l?p l?i, m?i l?n l?p l?i t??ng ?ng m?t cay. Nhan t? th? nh?t la n?ng d? x? ly chlorate kali bao g?m 0, 8, 16 va 24 g/m d??ng kinh tan va nhan t? th? hai la co ho?c khong co khoanh canh. Chlorate kali d??c ap d?ng b?ng cach t??i vao d?t, xung quanh tan cay. Khoanh canh d??c khoanh m?t ngay sau khi x? ly chlorate kali v?i b? r?ng v?t khoanh t? 3-5 mm. K?t qu? cho th?y, x? ly KClO3 v?i li?u l??ng 24 g/m d??ng kinh tan co t? l? ra hoa cao nh?t (72,4%). Bi?n phap khoanh canh co tac d?ng lam tang t? l? ra kho?ng 36%. X? ly Chlorate kali v?i li?u l??ng 24 g/m d??ng kinh tan k?t h?p v?i khoanh canh kich thich nh?n Xu?ng C?m Vang ra hoa s?m h?n d?i ch?ng 30 ngay. X? ly KClO3 lam gi?m ham l??ng d?m t?ng s? nh?ng tang t? s? C/N trong la ? giai do?n ra hoa. T? l? ra hoa co t??ng quan ngh?ch v?i ham l??ng d?m t?ng s? trong la (r = -0,83**) nh?ng t??ng quan thu?n v?i t? s? C/N (r =0,82**).

T? khoa: Chlorate kali, khoanh canh, mua ngh?ch, Xuong C?m Vang