Cassava

Yield Stability of Thai Cassava (Manihot Esculenta Crantz) Varieties Grown in Late

Rainy Season.

Boonseng O.,¹ C. Rodjanaridpiched,² E. Sarobon,² P. Duangpatra, ³ A. Summart,⁴ and P. Chatwachirawong²

1Rayong Field Crops Research Centre, Muang, Rayong. 202250 Thailand.

^{2Department of Agronomy, Faculty of Agriculture, Kasetsart University, Bangkok. 10900. Thailand.
^{3Department of Soil Science, Faculty of Agriculture, Kasetsart University, Bangkok. 10900. Thailand.
^{4Banmai Samrong Field Crops Experiment Station, Sikhiu, Nakhon Ratchasima. 30340. Thailand.
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Growing cassava in the late rainy season is becoming popular among farmers in order to reduce weed problems. Varieties used for growing in the late rainy season are the same as those grown in the normal season (early rainy season). Performance of these varieties when grown in the late rainy season is not known and should be studied in various locations (environments). Thus, the objective of this study was to investigate the performance of cassava varieties for either adaptability to a wide range of environments or to specific environments in term of yield stability. Five Thai cassava cultivars, namely Rayong 1, Rayong 60, Rayong 90, Si Racha 1 and Kasetsart 50 were planted in the late rainy season (October) 1992 in 11 locations (environments). In each environment or location, the 15-15-15 compound fertilizer was applied at rate of 0, 313, 625 and 1,250 kg/ha. The analysis shows that the mean square of variety (genotype) x environment interaction was highly significant (Table 1), indicating that the cassava varieties tested yield differently under different environments. Data from Table 2 show that within the low yielding environments such as Burirum Farm, Dankhuntod Farm, Korat Farm, Lat Bau Khao Farm, Rayong Field Crops Research Centre, Sikhiu Farm and Seong Sang Farm Kasetsart 50 gave the highest yield. On the other hand, within the high yielding environments Rayong60 gave the highest yield (at Khon Kaen Field Crops research Centre and Mukdahan Field Crops Experiment Station), while Rayong 90 gave the highest yield at Banmai Samrong and Maha Sarakham Field Crops Experiment Stations. The analysis (Table 1) also shows that the mean squares of variety (genotype) x fertilizer interaction was highly significant, indicating that the cassava varieties tested yielded differently under different rate of fertilizer. Kasetsart 50, Rayong 1, Rayong 90, and Si Racha produced good yields at 313 kg of 15-15-15 /ha, whereas Rayong 60 produced highest yield at 625 kg/ha (Table 3). Thus, it can be concluded that Kasetsart 50 is suitable for growing in relatively low yield environments. On average, the varieties tested produced their highest yield at a medium rate of fertilization of 625 kg of 15-15-15 /ha, but Kasetsart 50, Rayong 1, Rayong 90 and Si Racha produced similarly high yield at lower rate of 313 kg of 15-15-15 /ha

Bibliography

Gauch, H.G. 1988. Model selection and validation for yield trials with interaction. Biometrics 44 : 705-715

Table 1 Variance components and percent of sum of squares from the total genotype x
Environment interaction variation (in parentheses) of dry root yield of 5 cassava
Varieties, applied with 4 rates of mixed fertilizer 15-15-15 under 11 environments.
Source of variation			df		Sum of squares							Mean square
Environment (Env.)			10		7268.09					726.81**
Rep. Within Env.			22		426.12							19.50*
Genotype (Gen.)			4		893.15							223.29**
Gen. X Env.			40		1176.17							29.40**
PCA 1			13		713.35 (60.65%)							54.87**
PCA 2			11		282.87 (24.05%)							25.71*
Residual			16		179.95							11.24 ns
Rep x Gen. within Env.			88		1113.60							12.65
Fertilizer (Fer.)			3		582.60							194.20**
Gen. X Fer.			12		55.58							4.63**
Env. X Gen. X Fer.			150		838.22							5.59**
Rep. X Fer. within Env. Gen.			330		618.09							1.87
^{ns non-significant}
significant at p < 0.05
Table 2 Mean dry rood yield of 5 cassava varieties, applied
with 4 rates of mixed fertilizer 15-15-15 under 11 environments.
Environments	Varieties							Mean	PCA1		PCA2
	KU50	R1		R60		R90	SR1
BMS	12.83	14.62		12.43		15.48	11.52	12.83	0.25		0.63
BR	7.22	4.86		5.95		6.09	4.75	7.22	0.19		-0.26
DAN	11.58	9.1		10.32		10.35	9.00	11.58	0.17		-0.28
KK	16.3	11.55		16.98		13.44	7.71	16.3	-0.97		-0.48
KR	9.84	8.43		9.33		9.68	6.38	9.84	-0.05		0.01
LAD	8.47	7.31		7.48		8.44	6.27	8.47	0.19		0
MAH	17.75	18.52		16.96		19.44	16.55	17.75	0.32		0.39
MUK	12.01	11.99		13.67		13.45	4.73	12.01	-0.89		0.55
RY	11.69	9.49		10.61		10.74	8.93	11.69	0.12		-0.21
SI	9.3	6.83		7.6		8	7.71	9.3	0.37		-0.34
SS	8.07	6.87		6.86		7.97	6.34	8.07	0.29		-0.03
PCA 1	-1.05	0.2		-2.94		-0.3	4.1
PCA 2	-2.13	2.38		-1.02		2.01	-1.24
Note : BMS = Banmai Samrong Field Crops Experiment Station RY = Rayong Field Crops Research Centre
MAH = Mahasarakham Field Crops Experiment Station KK = Khon Kaen Field Crops Research Centre
MUK = Mukdahan Field Crops Experiment Station BR = Burirum Farm, Nonsuwan, Burirum.
DAN = Dankhuntod Farm, Dankhuntod, Korat. KR = Korat Farm, Muang, Korat.
LAD = Ladbaukao Farm, Sikhiu, Korat. SI = Sikhiu Farm, Sikhiu, Korat.
							SS = SeongSang Farm, SeongSang, Korat

^{** significant at p < 0.01}
Table 3 Mean dry root yield (ton per hectare) of 5 cassava varieties applied with 4 rates mixed
Fertilizer 15-15-15 under 11 environments. 1/ In a row, fertilizer means followed by a common letter are not significantly different at p < 0.05 by LSD

2/ In a row, fertilizer means within each variety that followed by a common letter are not significantly different

at p < 0.05 by LSD

Cassava 1