A Clustering Study on Selection of Parents in Cotton Breeding

MATERIALS AND METHODS

This study was conducted at Nazilli Cotton Research Institute (latitude; 37°44’-37°-49’ N and longitude; 27°44’-27°50’ E). Eighty-one cotton genotypes of genetic stocks (Gossypium hirsutum L. and Gossypium barbadanse L.) were used as a material (Table 1). The plots were 12 m length and consisted of one each row. The planting norm was 0.7x0.2 m, the density was 71420 plant ha^-1. Conventional growing practices were applied though growing season for Aegean Region of Turkey.

Table 1:	Eighty-one cotton genotypes of genetic stocks (G. hirsutum L. and G. barbadanse L.)

Genotypes in genetic stocks were evaluated from the point of plant height (PH;cm), first picking percentage (FPP; %), Number of Days Boll Opening (NDBO; day), Boll Opening Degree Days (BODD), Boll Weight (BW; g), seed index (SI; g) and lint percentage (LP; %), fiber length (mm), fiber fineness (mic) and fiber strength (g/tex). Hierarchical clustering was carried out using UPGMA (Unweighted Paired Group Method using Arithmetic Averages) for fiber length, fiber fineness and fiber strength which was recommended when the different size of groups and number of characters were used (Rincon et al., 1996).

RESULTS AND DISCUSSION

The cotton quality parameters, fiber length, fiber fineness and fiber strength concerning genotypes were used to compute a dendrogram showing Euclidian distance in order to define relationships among the genotypes. Ten groups were defined by cluster analysis and distribution of fiber length and fiber fineness of cluster groups were presented in Cluster B and I contain 5 and 3 genotypes with having considerable values for fiber length and fiber fineness, respectively. In the cluster B, 8 (Askabat 100; G. barbadense L.), 54 (Sealand 542; G. hirsutum L.), 33 (Giza 45; G. barbadense L.), 22 (Delcerro; G. arboreumxG. thurberixG. hirsutum L.), 31 (Ege 69; G. hirsutum L.) had long stable and finest fiber characteristics. Cluster I were 35 (Giza 75; G. barbadense L.), 34 (Giza 70; G. barbadense L.) and 30 (ED 110; G. hirsutum L. ). The pedigrees of Ege 69 and ED 110 are 2421-A RussianxSealand 542 and Ege 69xDelcerro, respectively. Otherwise, when the mean and standard errors of genotype characteristics were evaluated in Table 2, FPP, NDBO and BODD of Cluster B were 45.48±24.62%, 124.00±7.78 days and 1372.40±67.57 growing degree-days, respectively. These values for Cluster I were 29.17±27.23%, 132.33±12.42 days and 1439.33±106.04 growing degree-days, respectively. It could be defined that Cluster B and I had high plant height and seed index, late maturity and low lint percentage. The choosing of parents from these clusters may be a problem in terms of earliness and lint percentage for long stable cotton breeding.

Cluster J, H, F, G, E and D, total 65 genotypes, were in range of stable length for upland cotton (from 28.0 mm to 32.00 mm). Also, there were three different groups for fiber fineness. Fiber fineness values of first, second and third groups ranged from 3.0 to 3.8 mic, 3.8-4.7 mic and 4.7-5.5 mic., respectively (Fig. 1). H group (Carmen, DPL 5690 and Sicala 33) had the longest fiber length in these groups, while these genotypes considerate with late maturity characteristics. Cluster D include Stoneville’s cultivars (Stonoville 453 for South Eastern Anatolia Region’s standard cultivar); Nazilli 84-S, Nazilli 87 and Nazilli 143 (cultivars improved by Nazilli Cotton Research Institute and standard cultivars for Aegean Region; Sayar 314 (standard cultivar for Cukurova Region); Dp 388 and DAK 6 with having thicker fiber, higher lint percentage and the highest seed index.

Green fiber (81), 153 F (1) and Okra 201 (49) were in Cluster A and this group had short and finest fiber. Also, this cluster could be defined as late maturity and lower boll weight. Cluster C include Aleppo 1 (Syria origin) and Dark Yellow Fiber and had short and coarse fibers. Also, Mc Namara (41; Red Leaf) and Yellow fiber (24) genotypes showed similar characteristics.

Fig. 1:	Clusters include different numbers of genotypes

Table 2:	Mean±SE of genotype characters of cluster groups
PH; Plant Height, FPP; First Picking Percentage, NDBO; Day Number of Days Boll Opening, BODD; Boll Opening Degree Days, BW; Boll Weight, SI; Seed Index, LP; Lint Percentage

The NDBO and BODD values of Carmen (14; Cluster H) and Nazilli 84 S (44; Cluster D), Aegean Region standard cotton cultivars, were 130; 1425 and 119; 1327. The first factor in choosing parents continues to be yield; stability is the second factor (Esbroeck and Bowman, 1998). According to same authors, adapted cultivars have been intercrossed to such extent that a cross involving distantly-related parents requires the use of un-adapted germplasm. Unay et al. (2003) and Sezener et al. (2006) revealed that Nazilli 84 S was the most stable variety for lint yield, while Carmen was group of the mid-adaptation to all environments. In the long staple cotton breeding, the genotypes in Cluster B and I should be crossed to Aegean Region standard cotton cultivars, Nazilli 84 S and Carmen. In the cluster B I, Askabat 100, Giza 45, Giza 75 and Giza 70 belong to Gossypium barbadense L. The probable barbadensexhirsutum crosses could contain a large number of undesirable genes or gene combinations especially for maturity or earliness. Therefore, long staple cotton breeding programs should contain upland genotypes such as Sealand 542, Delcerro and Ege 69.