Study of Genetic Behavior of Some Quantitative and Qualitative Traits in Sorghum hybrids [Sorghum bicolor L. Moench]

Saoud Shehab
Commission for Scientific Agricultural Research-
Department of Crop Research Administration
Faculty of Agriculture- Damascus University


This study was conducted in General Commission for Agricultural Scientific Research between (1999-2001). Crosses between (4) male sterile lines introduce from India and Zimbabwe and (15) local and exotic male parents (lines and varieties) were made in (1999), to produce superior hybrid yields comparing with local varieties. The derived thirty-six fertile hybrids, second generation and their parents were evaluated in Damascus and AL Raqqa locations in 2001. Entries were arranged in a line x tester mating design according to randomized complete block design with two replications for location. Study of cytoplasmic-male sterility behavior was assessed in (2002).
All evaluated traits showed heterosis with different magnitudes. The values of mid-parent and high-parent heterosis exceeded 100% for seed weight and seed number traits. This has been obviously shown in the crosses involved parents arose from different geographical areas. The highest value of heterosis for seed number and seed weight was recorded in the hybrid (IZRAA 41 x MMS48A).
Some hybrids had positive specific combining ability for some traits,  but (AZRAA 41 x MMS48A) was the only hybrid which had positive specific combining ability for seed weight/head only. This hybrid resulted from a cross involved parents with positive general combining ability emphasizing the importance of additive x additive effect. This combination could be utilized in the hybrid programs.
Narrow-sense heritability for plant height and head length were relatively high in Damascus location (65% and 56%) respectively, but the narrow-sense heritability of all traits in Raqqa location was low, the range was from 3% for threshing percentage to 34% for plant height, and from 22% for seed weight/head to 60% for plant height in the combined estimation.
Genetic advance estimates were relatively low for all traits, the range was from 0% for 100 seed weight to 28.3% for plant height (Damascus location). And from 0.02% for seed numbers/head to 15.2% for plant height (Raqqa location), and from 5.8% for days flowering to 26.5% for plant height (combined estimation).
Some characters as plant height and head length showed relatively high estimates of heritability but exhibited low values of genetic advance.
Therefore other traits had low heritability coupled with low values of genetic advance indicated predominance of non-additive gene action. This result implies that it will need several generations of selection to improve grain yield components and other traits.
Interrelationships of some agronomic traits in first generation revealed that seed weight/head was significantly and positively correlated with head width (r = 0.67**), threshing percentage (r = 0.43**), seed number/head (r = 0.85**) and 100 seed weight (r = 0.40**). The first three traits had significantly and positively correlated as the first generation, for that the selection for yield components will be more effective and increase yield sequence generations.
This study also enabled us classifying the (15) parents according to behavior of cytoplasmic-male sterility as: (9) were restorers, (3) maintainers, (3) partials (sterility or fertility). Positive results were obtained from transfer sterile character from exotic line (ATX629) to local lines (IZRAA-3 and RAZEENIH), by using back cross method.