Abstract
<p class="042abstractstekst">The study quantified the effect of gibberellic acid (GA<sub>3</sub>) as a pre-flowering treatment for male parent Giza 178 R and the influence of male to female ratio (2R:10A, 2R:12A, 2R:14A and 2R:16A) between male (R) to female (A) for two Cytoplasmic Male Sterility (CMS) lines (‘IR69625’ and ‘G46’) on hybrid rice seed production. The main plots were occupied by CMS lines while; GA3 application for male parent Giza 178R were arranged in the sub plots and male to female ratio was arranged in the sub-sub plots. The results indicated that, the, duration of floret opening, angle of floret opening, filaments exsertion, filaments length<strong>, </strong>anther length, plant height and number of tiller hill<sup>-1 </sup>of male parent Giza 178R were significantly at 300 g GA<sub>3</sub> ha<sup>-1</sup> concentration. Plant height, panicle exsertion, panicle length, flag leaf angle and 1000-grain mass of CMS were not significantly affected by the GA<sub>3</sub> application for male parent and male to female ratio, while, number of fertile panicles hill<sup>-1</sup>, panicle mass, seed set, seed yield and harvest index of CMS lines were highly significantly affected. The highest seed yield (2.880 and 2.950 t ha<sup>-1</sup>) was obtained by CMS line IR69625A using 300 g GA<sub>3</sub> ha<sup>-1</sup> of male parent Giza 178R with male to female ratio of 2R:14A during both seasons.</p>
Highlights
2 MATERIALS AND METHODSHybrid rice breeding, which was initiated in Egypt has led to great improvement in rice production (Zaman et al, 2002; Hamad, 2018)
The GA3 application rates (0, 150, 200 and 300 g GA3 ha-1) for male parent Giza 178R was allocated to subplots and male to female ratio (2R:10A, 2R:12A, 2R:14A and 2R:16A) between male (R) to female (A) was arranged in the sub-sub plots
The results indicated that, the foliar application of GA3 significantly increased panicle exsertion, seed set and seed yield of cytoplasmic male sterile (CMS) lines at 300 g ha-1 concentration
Summary
Hybrid rice breeding, which was initiated in Egypt has led to great improvement in rice production (Zaman et al, 2002; Hamad, 2018). No information is available on how these CMS lines will respond to GA3 application with reference to their heading characteristics Such data are very important to generate baseline information whether genotypic variations exist among CMS lines in response to GA3 pre-flowering treatment and whether such responses follow similar trends. This will help in identifying CMS lines which are responsive to GA3 application to maximize their utilization in the development of new hybrid rice varieties with higher seed yield potential. The objective of this investigation was to study the performance of Giza178R male parents as affected by GA3 application rates and male to female ratio on the growth characteristics and hybrid seed yield production of two CMS lines (IR69625A and G46A)
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