IDENTIFICATION OF DROUGHT TOLERANT MOLECULAR MARKERS IN RICE (Oryza sativa L.) I- ASSESSMENT OF F1 GENOTYPES UNDER NORMAL AND DROUGHT CONDITION

Abstract

The present study was carried out at the Experimental Farm of the Rice Research and Training Center (RRTC), Sakha, Kafer EL-Shiekh, Egypt, during three successive rice growing seasons 2010, 2011 and 2012 aiming to establish combiners that may have drought tolerance characters by hybridization between local sensitive and imported tolerant rice cultivars which will be subjected to aggressive Simple Sequence Repeat (SSR) molecular technique. So, eight genotypes namely; Moroberekan, IET1444, Azucena, IRAT170, GZ530-20-10, Giza177, Giza 178 and Sakha101 were chosen for line by tester cross. The hybrid grains were grown in 2011 as F1 and transplanted in a randomized complete block design (RCBD), with three replications, (each F1 cross transplanted between its parents). All the genotypes (eight parents and 15 F1 crosses) were planted under both normal and imposed drought conditions. The obtained results exhibited that, the parents Moroberekan, IET 1444, Giza 178 and Sakha 101 and the F1 crosses involved these parents, in particular the crosses Moroberekan x Giza177 and IET 1444 x Sakha 101 showed the most favorable mean performances values for root, yield and physiological characters, under stress conditions. Moreover, under drought stress, the following F1 crosses; IET 1444 x Giza177, IRAT 17 x Sakha101 show remarkable increase in the mean performance of average panicle length, average number of panicles per plant, average grain yield per plant as well as harvest index. However, insignificant heterotic effects were recorded for average root volume (RV) with the F1 combiner; GZ350-20-10 x Giza178. Neverthless, root to shoot ratio (R:S) did not show insignificant heterosis effects under drought condition. The most desirable crosses under normal and drought stress were; Moroberekan x Giza177, Moroberekan x Sakha101, IET 1444 x Giza178, IET 1444 x Sakha101. Since these crosses maintained the most favorable shoot, root, yield and physiological characters under both normal and drought stress conditions. The vigorous growth of F1 rice hybrids may partially attributed to the development and function of the root system. Also, it was found that F1 hybrid surpassed parents in the total root length, number. of root per plant. As a result, the root system of F1 hybrids was not only greater in volume, but also longer in length. Additionally, root to shoot ratio showed higher values than that of parents. Signficant GCV estimates were recorded for all the studied traits except the parents IET 1444 for average root volume per plant and the parent Giza 178 for root to shoot ratio under normal condition and Giza 177 for average number of roots per plant for number of roots per plant. Also, signficant GCV estimates were recorded for all the studied traits except the parents IRAT 170, Giza 177 and Giza 178 for average relative water content.