Cotton line GDPSR 38-136 (Tak Fa 2)

Parinya Sebunruang , psebunruang@yahoo.com

Nakhon Sawan Field Crops Research Centre, Tak Fa, Nakhon Sawan 60190

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Cotton is one of the most importance economics crops, particularly for the textile industry in Thailand. It is used as raw material for making clothes, fabrics both for domestic used and for export, which is about 100,00 million Baht (Approx. 2,273 US$) per year. In the year 1980/1981, the planting area to cotton was 154,672 ha. but now the planting area decrease dramatically to be only 26,115.5 ha. With the production is only 36,340 tons, that is not enough for domestic used. Therefore, it is necessary to import cotton about 18,700 million Baht (Approx.425 mUS$) every year. Growing cotton has many problems, such as diseases and insects pests. Sri Sam rong 60 (SR60) and Sri Sam rong (SR 2) are the only recommended varieties in the present. But these varieties had been used by Thai farmers for more than ten years. Now, the textile industry want the long staple cotton (1.15-1.20 inch) or medium length (1.00-1.04 inch) for making better quality fabrics and clothes for export purpose. SR 2 is a good variety for this purpose but the weak point is low yielding ability (1,750-2,063 kg per ha). In August 1999, The Royal Thai government has announce the exempt of imported duty, this result to price of domestic cotton will be base on staple quality with the standard of T –3 staple length or longer than 1.09 inch. The Nakhon Sawan Field Crop Research Centre (NSFCRC) is using this standard for the improvement of the new cotton line, that should be better than SR 2 in both staple quality and yield potential. Until the year of 2001, a new cotton line name, GDPSR 38-136 which meet the above requirement was obtained.

Improvement Background

Cotton line GDPSR 38-136 derived from crossing of variety GDI 9-67 and Pima 79-106 and then crossed by SR 2 [(GDI 9-67 x Pima 79-106) x SR 2)] by Mr. PAYON Khumpai , a former cotton breeder of the NSFCRC with the objective of merging all the good characteristics of each variety mention above in to one variety. GDI 9-67 is derived from crossing of Sri Sam rong 2 (SR 2) a good staple quality and resistance to leaf curl disease, and Nakhon Sawan 1 (NS 1) a high yield potential variety with spreading plant type and early maturity variety. Then using modified bulk selection method for selection against leaf curl disease in artificial inoculation plot in field condition. Until the 7 generation (F 7) the GDI 9-67 was obtained which is resistant to leaf curl disease, spreading plant type, high yield, and big cotton boll. But one weak point of this line was observed, that was low staple quality. Then this line was crossed to Pima 79-106, a very good staple quality variety. After 6 generation of selections, This line then crossed again to SR 2 to up grade the percentage of ginning out turn.

Characteristic of cotton line GDPSR 38-136

  1. Obviously longer staple length than SR 60 and SR 2. Staple length, Uniformity, and micronair are equal to SR 2 and SR 60.
  2. Average yield is 1,931 kg. per ha. Which is higher than SR 2 about 7%
  3. Resistance to leaf curl disease in the same level of SR 2 and SR 60 in the artificial inoculation plot.

Table 1. Characteristics

Character\Line or Variety GDPSR 38-136 SR 2 SR 60

1. Plant type Spreading Spreading Spreading

2. Hair on the stem Short hair None None

3. Leaf shape Digitate Palmate Palmate

4. Leaf colour Green Green Green

5. Hair on Leaves Little Little Little

6. Leaf margin Smooth Smooth Smooth

7.Leaf loop Rise Rise Rise

8. Pigment gland on leaf vein Yes Yes Yes

9. Petal colour Cream Cream White

10. Anther colour Cream Cream Cream

11. Bract character Wide Wide Wide

12. Ball character Oblong Round Round

13. Fibre colour White White White

14. Staple Length Long Long Long

 

 

 

Table 2. Agronomic characters

Character\Line or Variety GDPSR 38-136 SR 2 SR 60

Yield (Kg/ha.)1 1,931 1,806 2,031

Flowering date(days)2 53 55 51

Harvesting date (days)2 120-160 120-160 110-160

Plant Height(cm)2 143 128 149

Number of monopodia branches per plant2 2 3 2

Number of sympodia branches per plant2 16 13 14

Table 2. (Cont.)

Character\Line or Variety GDPSR 38-136 SR 2 SR 60

Number of ball per plant2 29 24 25

Weight(g)2 6.07 6.00 6.92

Number of seed per boll2 33 31 36

100 seed weight(g)2 11.09 11.39 11.05

Reaction to leaf curl2 Resistance Resistance Resistance

Ginning out turn2 37.7 39.0 39.7

 

 

Table 3. Staple quality

Character\Line or Variety GDPSR 38-136 SR 2 SR 60

Length(inch)1 1.20 1.11 1.09

Strength(gram/tex)2 20.9 19.2 18.5

Uniformity(%)2 52 53 52

Micronair3 4.0 3.7 4.7

Source: 1. Average from 66 trials

2. Average from 5 trials in 1999.

3. Data from laboratory at NSFCRC.

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