1. Effect of Potassium Chlorate Concentration on Flower Initiation of Longan (Dimocarpus longan Lour.) in Soi Dao District, Chanthaburi.
Benjaporn Tangsukkasemsan
Faculty of Agricultural Technology,
Rambhai Barni Rajabhat University, Chanthaburi, Thailand.

2. Chanthaburi Location Eastern part of Thailand 245 km from Bangkok
Area : 6,338 km2

5. Introduction Longan (Dimocarpus longan Lour.) , cultivar “Daw”
an economic crop of Thailand
Fresh eaten
preserved: canning / dried

6. Products

7. longan require a period of cool and dry climatic conditions for induction of flowering
northern provinces i.e : Lumpun, Chiang Mai and Chiang Rai.

8. longan growers have discovered an alternative method of floral induction in the absence of suitable climatic conditions.
application of chlorate compound : potassium chlorate or sodium chlorate

9. Chanthaburi

10. Plantation and Yield 1996 -2007 Year Planting Area (acre)
Harvested area
(acre) 
total Yield
(ton)
Average yield/Acre  
1996
4,102
1,965
1,979
1007
1997
3,982
1,907
1,918
1005
1998
4,238
2,611
6,301
2412
1999
4,999
3,649
2000
5,648
4,294
19,047
4360
2001
8,062
19,273
4487
2002
11,058
5,460
27,051
4955
2003
12,620
6,930
34,813
5025
2004
19,378
9,948
49,782
5000
2005
32,462
20,724
104,467
5040
2006
33,130
21,813
103,798
4757
2007
33,462
26,789
129,867
4847

11. Suggestion rate
Subhadrabandhu and Yapwattanaphun, (2000): Cultivar 'Daw' requires 8 g/m² of potassium chlorate as soil drench
Somchai Ongprasert and Winai Wiriya-Alongkorn (2007) : 200 mg of potassium chlorate per liter of standard nutrient solution

12. C. Sritontip et. al. : soil drenched with KClO3 at 5 g/m-2 of canopy of 4-5 year- old- longan trees
Mike A. Nagao and Elodie B. Ho-a. (2000) : application of 250 – 500 grams of KClO3 around the canopy
Li XiangHong (2004) :130 g/m2 seven-year-old trees of longan cultivars Chuliang and Shixia

13. Chanthaburi growers practice
soil drench
200 grams/tree for the 4-year- old- trees
By the following years, the amount of potassium chlorate used was double.
Shortening longan tree life

14. The purposes of the study was to determine the suitable amount of KClO3 which were able to initiate flower buds
of 7- year- old - longan tree.

15. Materials and Method completely randomized design
6 treatments and 5 replications.
Treatment:
200 gm /50 L water/tree
400 gm/50 L water/tree
600 gm/50 L water/tree
800 gm/50 L water/tree
1000 gm/50 L water/tree
1000 gm/30 L water /tree (control)

16. experimental units Thirty longan trees seven-year- old
Fifty healthy vegetative shoots/tree
The potassium chlorate was applied on June 13, 2007.

18. Result : Days flowering shoots observed
KCLO3 concentration
days ns
200 gm/ 50 l water/tree
35.46
400 gm/ 50 l water/tree
29.35
600 gm/ 50 l water/tree
32.62
800 gm/ 50 l water/tree
37.25
1000 gm/ 50 l water/tree
39.96
1000 gm/ 30 l water/tree
33.83

20. Result : Percentage of flowering shoot
KCLO3 concentration
flowering shoot (%)ns
200 gm/ 50 l water/tree
52.00
400 gm/ 50 l water/tree
53.20
600 gm/ 50 l water/tree
72.80
800 gm/ 50 l water/tree
54.80
1000 gm/ 50 l water/tree
48.40
1000 gm/ 30 l water/tree
69.20

21. Yield of logan: Mean index
KCLO3 concentration
Mean index
#1ns
#2 ns
#3 ns
#4 ns
#5 ns
200 gm/ 50 l water/tree
3.8
2.2
3.0
1.6
2.0
400 gm/ 50 l water/tree
1.4
4.0
1.2
2.4
600 gm/ 50 l water/tree
2.6
800 gm/ 50 l water/tree
3.2
1000 gm/ 50 l water/tree
2.8
4.2
1000 gm/ 30 l water/tree

22. yield index = none
2 = yield 1-20 %
3 = yield %
4 = yield %
5 = yield %
6 = yield %

23. Yield of logan: mean weight per tree (kg)
KCLO3 concentration
Mean weight /tree (kg)
#1ns
#2 ns
#3 ns
#4 ns
#5 ns
total
200 gm/ 50 l water/tree
25.80
13.84
12.70
4.50
4.46
61.30
400 gm/ 50 l water/tree
4.76
43.50
26.04
3.20
3.32
80.82
600 gm/ 50 l water/tree
15.00
14.02
26.20
2.00
8.40
65.62
800 gm/ 50 l water/tree
8.72
20.40
21.00
2.84
6.72
59.68
1000 gm/ 50 l water/tree
13.44
3.08
31.20
3.80
3.18
54.70
1000 gm/ 30 l water/tree
9.30
20.90
35.10
2.28
7.18
74.76

24. conclusion the average flower initiation period was 29-40 days.
The application of grams of KClO3/ 50 liters of water/tree give the highest percent of flowering shoot.
Not only flower initiation period but also percent of flowering shoot were non-significant.

25. Thank you