The experiment was carried out in strip plot design with three replications to evaluate 14rice genotypes under normal and water deficit in the field and biotechnology lab of Rice research and Training Center at Sakha Agricultural Research Station, Sakha, Kafr EL-Sheikh Egypt, during2021 and 2022summer seasons. Results revealed a wide variation among rice genotypes and their parents for agronomical characteristics and SSR markers. Data showed that days to maturity, plant height, Flag leaf area, number of panicle-1 , Panicle length, number of filled and unfilled grains panicles-1 as well as grain yield t ha-1 were significantly affected by irrigation treatments. Grain yield was affected significantly according to the genotypes and irrigation treatments. The combination between Egyptian Yasmin with normal irrigation produced the highest values of grain yield with the lowest percentage(14.58%) of yield reduction compared to its production under water deficit conditions. While, the lowest values of grain yield were obtained with Nerica7 (V2) under water shortage conditions with the highest percentage(33.63%) of yield reduction compared to its production under normal irrigation. Fifty SSR markers were used for estimating the genetic variation among the 14rice genotypes. Rice genotypes were divided into two main groups based on the polymorphism revealed by the SSR markers. The first group has the aromatic genotype, Egyptian yasmine and the promising newly developed genotype No.2. While, the second main group has the other tested rice genotypes, NERICA7 and the other genotypes. The data indicated that phenotypic variance was generally superior than genotypic variance for all studied traits.
In order to investigate the effect of sowing dates on rice yield and its components a field experiment was carried out in Randomized Complete Block Design (RCBD) with three replications at the Experimental Farm of Sakha Agricultural Research Station, Sakha, Kafr EL-Sheikh Egypt. 14 rice genotypes were tested at different sowing dates, April 1 st , April 15 th , May 1 st and May 15 th during the two successive rice seasons 2017 and 2018. The studied characters were i.e., flag leaf area, chlorophyll content, plant height, number of panicles per hill, number of filled grains per panicle, number of unfilled spikelets per panicle, 1000-grain weight (g), grain yield (t/ha), number of days from sowing to heading and growth degree days. Analysis of variance indicated that rice genotypes were significantly different for all the studied traits. The highest values of grain yield and most of the studied characters were observed under April 15 th followed by May 1 st sowing dates. Sakha108 and GZ6903-1-2-2-1 produced the highest grain yield followed by IR77510-68-1-3-3.
Yield and its components traits of rice varieties were studied to estimate the relationship between grain yield and its components. Sixty rice genotypes were used in this research. A field experiment was conducted in a randomized complete block design with three replications at Sakha Agricultural Research Station, Kafr elsheikh, Egypt during 2017 and 2018 seasons. The results revealed that the Giza 178, GZ 9399-4-1-1-3-2-2 and Giza 177 exhibited the highest values of no.of filled grains panicle-1 and grain yield t/ha. The mean square analysis for the rice genotypes was highly significant for all studied traits, indicating that the differences among the rice genotypes and their traits. Chlorophyll content, flag leaf area, number of panicles plant-1 , panicle length and number of filled grains panicle-1 showed positive direct effect on grain yield, while, rest of traits showed negative effect on grain yield. This indicates that more number of filled grains panicle-1 is a highly reliable component of grain yield. Another important character with direct effect on grain yield is number of panicles plant-1 and flag leaf area which showed positive direct effect on grain yield. Hence, number of panicles and filled grains panicle-1 should be given a prior attention in rice improvement program because of their major influence on yield. Highly significant and positive correlations were found between grain yield and each of no.of panicles plant-1 , panicle length, no.of filled grains panicle-1 and 1000-grain weight.
Two field experiments were conducted at the farm of Sakha Research Station, Kafr el-sheikh, Egypt in 2016 and 2017 rice seasons to study the performance of some rice genotypes under both different plant spaces and various nitrogen levels. Rice varieties i.e. SP70 (Sakha108), GZ9461, GZ7112 and GZ9057 (Giza 179) were used and cultivated under three spaces namely 15x20, 20x20 and 25x20 cm with three nitrogen levels i.e. control (without N-application), 110 and 165 kg N/ha. Statistical design of the experiment was split-split plot design. Rice varieties were applied in the main plots and plant space was allocated in the sub plots, while sub sub plots received nitrogen levels. The studied characters such as chlorophyll content, plant height, number of tillers and panicles, panicle length, panicle weight, 1000-grain weight, grain and straw yield were estimated. The main results revealed that the different genotypes slightly differed in their characters under study according to genetic background. The space of 25x20 cm was the best for all the studied characters of the tested genotypes except panicle length which responded to medium space 20x20 cm. The narrowing space of 15x20 cm was not suitable for all the genotypes and decreased most of the studied characters. The application of 165 kg N/ha caused an increased in the growth, yield attributes and grain plus straw yield. Results also indicated that the combination of wider space 25x20 cm with 165 Kg N/ha caused as a significant increase in all the previously mentioned characters expect 1000-grain weight which reached to its maximum value under both narrowing space 15x20 cm and control treatment (without N-application). The combination of all the genotypes under study with the space of 25x20 cm and 165 kg N/ha produced the same greatest grain yield except GZ7112 which gave the least. Straw yield of all the genotypes was nearly the same under both medium space (20x20cm) and narrowing space 15x20cm when fertilized by 165 kg N/ha specially GZ9057 which produced the highest straw yield under the same space and level of nitrogen.
Eight advanced inbred lines derived from different yellow maize populations were crossed in a half diallel mating scheme in 2010 season at Gemmeiza Agric. Res. Station. The resultant 28 crosses along with two commercial check hybrids i.e. SC 166 and SC 173 were evaluated at two locations i.e. Gemmeiza and Mallawy Agric. Res. Stations in 2011 season. Mean squares due to crosses, G.C.A. and S.C.A. were highly significant for all studied traits. The ratio of Ʃg2i/ ƩS2ij indicated that the nonadditive gene effects played the major role in the inhertance of all the studied traits. For grain yield, one parental inbred line P3 had significant positive GCA effects and six crosses P1xP2, P1xP6, P2xP4, P3xP8, P5xP7 and P6xP7 had significant or highly significant positive SCA effects. One cross P3xP8 gave similar productivity to that of SC 166. Also two crosses P3xP5 and P5xP7 exhibited similar yield performance to that of the check hybrid SC 173, since no significant difference. These promising crosses may be released as commercial hybrids by maize research program after further testing. Keywords: maize, diallel crosses, gene effect. INTRODUCTION: Diallel crosses in maize was developed by Sprague and Tatum (1942) who partitioned the variation among F 1 crosses resulting from inbred lines to general (G.C.A.) and specific (S.C.A.) combining ability. Matzinger et al. (1959) revealed that the G.C.A. variance is a function of additive variance, while S.C.A. variance is a function of the non-additive variance. Griffing (1956) gave a complete analysis of diallel crosses for fixed and random set of parents. El-Shamarka (1995), Mostafa et al. (1996), Abd El-Aty and Katta (2002) and Ibrahim et al. (2010) reported that specific combining ability effects were much more important in the inheritance of grain yield and its components.
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