Genetic Behavior of Some Rice Root Characteristics, Yield and Yield Components as Affected by Water Deficit

Abstract

Eight local and exotic cultivars of rice were crossed to obtain 28 F1 crosses, through half diallel mating design. The eight parents and their 28 F1s ( excluding reciprocals) were grown in a randomized block design with three replications at the farm of Sakha Research Station, Sakha, Kafr El-Sheikh, Egypt in 2020 and 2021 rice seasons. GCA and SCA were significant for most of studied traits. GCA/SCA ratios were found to be less than unity for all studied traits, indicating that the non-additive type of gene action was great importance in the inheritance of these traits. Estimates of GCA effects indicated that, the parent IET1444 was a good general combiner for most of studied characters. The hybrid combinations IR 65600-77×Nerica 9 were the best SCA for most of studied characters. IR 65600-77×Nerica 9 rice hybrid exhibited significant and highly significant positive estimates of heterosis as a deviation from mid and better parent for root length, number of roots/plant, root volume, root/shoot ratio, relative water content, flag leaf area, number of panicles/plant, 1000-grain weight and grain yield/plant under water deficit conditions, except root length for better parent was insignificant.

Studies on Combining Ability and Heterosis for Yield, Its Components and Some Grain Quality Traits in Rice Using Line X Tester Under Normal and Water Deficit

“…Estimates of both general (GCA) and specific combining ability (SCA) variances were found to be highly significant for all yield and its components and some grain quality traits under both water deficit and normal conditions, except grain shape traits under both conditions which were insignificant, indicating the importance of additive and non-additive genetic variances in determining the inheritance of these studied traits. The obtained results are in harmony with those previously observed by El-Naem (2010) and Daher et al, (2023). Mean performance of parents and their F 1 generation.…”

“…So, selection can be postponed to later generation. These findings were in agreement with those of EL-Naem (2010), El-Hity et al, (2015), Abo-Zeid (2016), Daher et al, (2023) and El-Agoury et al, (2023).…”

“…High GCA effects are related to additive and additive x additive components for genetic variation, the parents with higher positive significant GCA effects are considered as good combiners, while those with negative GCA effects are poor general combiners except in case of earliness, plant height, sterility %, grain shape and amylose content %. Similar results were obviously recorded by El-Naem (2010), El-Hity et al, (2015) and Daher et al, (2023). According to the results most of the studied genotypes were good combiners for water deficit conditions, consequently successful breeding program could be conducted for drought tolerance depending on pyramiding of gene specific to the studied traits and selection must be done in a later generation for most studied traits and under controlled conditions in order to minimize environmental effects.…”

“…Cross 11 L 236 x GZ 1368-S-5-4 recorded significant negative mid and better parent heterosis for sterility % under normal conditions while, cross IR 6500-127 x GZ 1368-S-5-4 was the best under water deficit conditions. Similar results were reported by several scientists like, El , EL-Keredy et al, (2003), Chitra et al, (2006), Saravanan et al, (2006), El Abd et al, (2007, Ganapathy and Ganesh (2008), Amudha et al, (2010), Daher et al, (2023) and El-Agoury et al, (2023).…”