30 Kasım 2013 Cumartesi

Determination of Reliable Selection Criterias for Early Generations in Potato Breedıng

 Determination of Reliable Selection Criterias for Early Generations in Potato Breedıng

Mete Kaan BÜLBÜL

ABSTRACT

              This study was conducted to evaluate the effectiveness of some visual selection criteria; and, to determine the reliable selection criteria for seedling and the first clonal generations in potato breeding programs aiming to develop of high yielding cultivars.
              The hybrid true potato seeds from eleven crossing combinations were obtained with crossing in Nevsehir during summer season in 2010. The seedlings from true seeds were grown in greenhouse in Hatay from December 2010 to March 2011 to obtain seedling generations. Then, one tuber of each seedling was planted into field in Kayseri in June 2011 to obtain the first clonal generation. In each generation, some morphological and agronomic traits, which can be used as selection criteria, were measured on each plant. A Breeder Preference Score (BPS) on 1-9 scale (1 the worst-9 the best) were also given to each plant based on their visual appearance before and after harvest. Then, the correlation coefficients were calculated between measured traits and given BPS in each generation. The correlation coefficients between BPS of seedling and the first clonal generation for each hybrid plant were also calculated.   
                 The results indicated that morphological characteristics of same plant could significantly vary between seedling and field generations. The selections for even tuber shape and eye depth may be misleading when the tuber size is very small in the seedling stage. It was concluded that the threshold level for BPS should be lower in the seedling stage due to weak correlation between BPS values of seedling and field generations.                                                                                                       


 Objectives


This study was conducted;

üto evaluate the effectiveness of some visual selection criteria; and,

üto determine the reliable selection criteria for seedling and the first clonal generations in potato breeding programs aiming to develop of high yielding cultivars.
Methods 
üThe measurements were done on 40 plants in each of 10 cross combinations.
üThe experiment for seedling generations were conducted in greenhouse at the Mustafa Kemal University in Hatay, Turkey between November 2010 and March 2011.  
üThe field experiment or the first field generation were conducted in the seed production site of Doga Seed Inc. İn the Tomarza, Kayseri, Turkey between June-October 2011.
üThe following morphological and agricultural traits were evaluated in both experiments: The seedling/plant height, stem diameter, width and length of terminal leaflet, tuber shape, eye depth, skin appearence, skin color, number of tubers per plant and tuber weight per plant.
üBreeding Preference Score (BPS) (1 very bad-9 very good) according to general appearance of haulms (BPSHw) and tubers (BPSTbr) were given to each plant.
Figure 1. Cross combinations used in the study.

Combinations            Number of Genotype of Seedling   Number of Genotype of First Clonal Genaration
Planted in theNumber of TPS Number of Tubers of Seedling Generation Number of Single Tuber Planted Number of Tubers of First Clonal Generation
1) Saturna X L.Olimpia 40 40 40 36
2) Kiebtz X Challanger 40 40 40 31
3) Alegria X Challanger 40 40 40 19
4) Tucan X Alegria 40 39 39 39
5) Fasan X Tucan 40 39 39 34
6) Pomqueen X Tucan 40 39 39 19
7) Atlantic  X R. Russet 40 40 40 38
8) Gala X Challanger 40 40 40 19
9) Saturna X Alegria 40 40 40 33
10) Tucan X Challanger 40 39 39 30



Table 1. Correlation coefficients between BPS values and evaluated plant traits

Seedling Generation
BPSHw BPSTbr
PH 0,6624** 0,1934
ST 0,573** 0,4567**
LW 0,0806 0,0989
LH 0,6957** 0,5512**
TS 0,2407** -0,0443
TED 0,178* 0,2689**
TSS -0,1517 -0,0275
TSC 0,0707 0,0725
TNT 0,292** 0,6541**
TWT 0,6855** 0,7061**
BPSTbr 0,4809


First Clonal Generation
BPSHw BPSTbr
PH 0,79** 0,3278**
ST 0,752** 0,3492**
LW 0,0317 0,0711
LH 0,2099* 0,1468
TS 0,073 0,2194*
TED 0,0416 0,1407
SS 0,1253 0,0104
SC 0,1352 0,0682
TNT 0,4308** 0,3969**
TWT 0,6146** 0,7621**
BPSTbr 0,5015**


                   Seedlin      Clonal
BPSHw BPSTbr
BPSHw 0,1793** 0,2356**
BPSTbr 0,1951** 0,1371*

**p>0,01,; p>*0,05
PH = Plant Height , TED= Tuber Eyes Depth, ST = Stem Thickness , TSS = Tuber Skin Smoothness, LW = Leaf Width                      TSC = Tuber Skin Color, LH = Leaf height, TNT = Total Number of Tubers, TS = Tuber shape, TWT=  Total Weight of Tubers, BPSHw = Breeder Preference Score  for  Haulms, BPSTbr = Breeder Preference Score  for Tubers

Key results

ØThe stem diameter, leaf length, tuber eye depth, number of tubers per plant and tuber weight per plant were significantly correlated with both BPSHw and BPSTbr in seedling generation .
ØIn seedling generation, the correlation between BPSHw and BPSTbr were also significant. 
ØIn the first clonal generation, plant height, stem diameter, number of tubers per plant and tuber weight per plant  were found as significant.
ØThe skin color can be used as a selection criteria starting from the seedling generation, while using tuber shape or eye depth as a selection criteria in seedling generation is not reliable for the subsequent generations.






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