Lama Khaled Alloun
Aleppo Research Center-
General Commission for Scientific Agricultural Research (GCSAR)
Faculty of Agriculture, Damascus University
This research was carried out in collaboration between the University of Damascus and the General Commission for Scientific Agricultural Research (GCSAR) during 2004 – 2009. The field work has been carried out at the GCSAR Research Station near the Tel-Hedya village whereas the genetic analysis was done at biotechnology facilities of the Aleppo Agricultural Research Centre.
The research aimed at (1) describing the local types of pepper grown in the provinces of Aleppo, Idleb and Hama; (2) developing pure line varieties through self-pollination; (3) promoting male sterility using 2,4-D instead of the stressful flower emasculation process; (4) making controlled crosses between local and foreign lines to develop new hybrids of pepper; and (5) carrying out a comparison among the new local lines using genetic fingerprinting and morphological description techniques.
Mass selection was done during the seasons 2004 and 2005 followed by single selection during 2006, 2007 and 2008. The selection was done based on the shape, pungency and color of fruits. The selection process resulted in 14 local lines and 6 foreign lines.
Promotion of male sterility on pepper lines 1 and 8 was carried out using 5 concentrations of 2,4-D (2,4-Dichlorophenoxy acetic acid):0, 10, 20, 30,40 mg/liter during 2007. The concentration 20 mg / liter gave the best results for promoting male sterility without affecting the fertility of ovules. The concentrations 30 and 40 mg / liter resulted in sterile pollens and ovules with poisonous effects on the plants. The concentration of 20 mg/liter increased the rate of parthenocarpic fruits without seeds.
Ten local varieties of pepper were crossed with five introduced varieties in top cross fashion to estimate heterosis and heterobeltiosis of 19 F1 hybrids. Heritability for earliness, fruit and seed yield and fruit characteristics have been evaluated during 2007-2008. Hybrids (line 4 x line 15, line 13 x line 15, line 9 x line 15, line 2 x line 19) showed highest heterobeltiosis for most traits studied. Heritability was more than 70% for fruit length, width, wall thickness and weight of 10 fruits. Based on the above, it could be concluded that in pepper, genetic variance is bigger than environmental variance and the selection is a better method to improve them. Heritability ranged from 50 to 70% for fruit yield per plant at physiological and biological maturity and number of days from planting to flowering. For the number of days from planting to physiological maturity, the heritability was only 32%. This indicates that the environmental variance for this character is bigger than the genetic variance and that hybridization is a better method to improve it.
Phenotypic description for 13 quantitative traits and molecular description using Simple Sequence Repeat (SSR) technology were assessed for fourteen local lines of pepper during 2008-2009. Cluster analysis for phenotypic and molecular description has sown distinctness between local lines. Except for line 2 and 7 from Hama and Aleppo respectively, the phenotypic and molecular description was different suggesting that they had the same genetic source. The differences between the two descriptions is due to the fact that SSR analysis measures genetic variation mainly in non-coding sequences which probably have a relatively minor impact on the phenotype. On the other hand, quantitative morphological traits are affected by environmental conditions, showing considerable variation.