The study was conducted throughout two seasons (2013 and 2014) at Xmatkuil farm at Merida, Yucatan, Mexico, to determine the relationships and the interactions between chemical compositions of condensed tannins and mimosine and their effects on the susceptibility of four Leucaena genotypes: Cunningham and K636 (L. leucocephala), and Nativa and KX2 (L. leucocephala 9 L. pallida) to the infestation of the most destructive insect pests; Leucaena Psyllids, Heteropsylla cubana Crawford, 1914 (Homoptera: Psyllidae), and Onion thrips, Thrips tabaci Lindeman, 1889 (Thysanoptera: Thripidae). Mimosine showed insignificant effect on the population of both pests. However, tannins exhibited a significant effect for Psyllid population on Nativa and K636, and highly significant effect on thrips for the same respective genotypes. The insignificant relationships of tannin effect were found for Cunningham and KX2 to the population fluctuations of Psyllid and Thrips

The study was conducted throughout two seasons (2013 and 2014) at Xmatkuil farm at Merida, Yucatan, Mexico, to determine the relationships and the interactions between chemical compositions of condensed tannins and mimosine and their effects on the susceptibility of four Leucaena genotypes: Cunningham and K636 (L. leucocephala), and Nativa and KX2 (L. leucocephala 9 L. pallida) to the infestation of the most destructive insect pests; Leucaena Psyllids, Heteropsylla cubana Crawford, 1914 (Homoptera: Psyllidae), and Onion thrips, Thrips tabaci Lindeman, 1889 (Thysanoptera: Thripidae). Mimosine showed insignificant effect on the population of both pests. However, tannins exhibited a significant effect for Psyllid population on Nativa and K636, and highly significant effect on thrips for the same respective genotypes. The insignificant relationships of tannin effect were found for Cunningham and KX2 to the population fluctuations of Psyllid and Thrips

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ABSTRACT The present work was conducted to study the effects of late planting on the performance of Egyptian cottons and to obtain information concerning the genetic control of earliness, lint yield/plant, lint% and lint index. Half diallel crosses among seven Egyptian cultivars were evaluated in the F2-generation under early and late planting conditions for two seasons. The reduction% in lint yield/plant caused by late planting was very high and reached 73.92% for the parents and 68.27% for the F2-populations. Both additive and non-additive gene effects were involved in the inheritance of days to first flower, earliness index, lint yield/plant, lint% and lint index, but the non-additive was much larger than the additive gene effects. Epistatic gene effects were found in the earliness traits and lint index in the second season, lint% and lint yield/plant in early planting in the second season. The graphics of Wr/Vr analysis for lint yield indicated that the distribution of the parents around the regression line was not consistent in both of early and late plantings in the two seasons. The genetic parameters indicated unequal distribution of dominance and recessive genes in the parents for all traits. The non-additive effects of genes were reflected in the departure from broad to narrow sense heritability. Therefore, pedigree and recurrent selection methods could be effective in late segregating generations. The promising F2-populations were “Giza 90 x Giza 80”, “Giza 90 x Giza 88”, “Giza 90 x Giza 86” and “Giza 86 x Giza 80”.

ABSTRACT Three cycles of pedigree selection from the F2 for grain yield/plant (GY/P) and one cycle from the F4 were achieved in four seasons under normal irrigation and drought stress environments. The objectives were to study the relative merits of pedigree selection for (GY/P) under drought stress and normal irrigation environments, to compare the efficacy of three cycles of selection started in the F2 with one cycle started in the F4 generation, and to study the sensitivity of the selected families. The genetic materials were 440 F2 individual plants stemmed from the cross Sids4 x Giza164. The reductions in GY/P caused by drought stress were 42.88, 13.64 and 25.81% for the F2 generation, Sids4 and Giza164; respectively. The reduction% in the other traits ranged from 0.58% for harvest index to 24.97% for number of spikes/plant (NS/P). The phenotypic correlations among traits in the F2 were larger under drought stress than under normal irrigation and in the same direction. Grain yield/plant showed positive correlation with NS/P and harvest index. Days to heading showed significant correlations with plant height, NS/P, GY/P and harvest index under both environments. The PCV and GCV of GY/P decreased from 76.01 and 45.81% in cycle0 (C0) to 20.15 and 19.16% after C3 under drought stress, and from 48.31 and 28.59% in C0 to 18.67 and 18.38% after C3 under normal irrigation; respectively. The realized heritability of GY/P increased from 23.02 and 41.06% in C1 to 67.24 and 42.92% in C3, under drought stress and normal irrigation; respectively. The observed genetic gain (OG) in GY/P of drought selected families in C3 was 20.69 and 17.98% under drought stress, and 31.18 and 30.13% under normal irrigation evaluation of the bulk sample and the better parent; respectively. While, the OG in GY/P of the normal irrigation selections was 17.12 and 14.49% under drought stress, and 20.43 and 19.47% of the bulk sample and better parent; respectively under normal irrigation conditions. The results of OG of the three cycles indicated that antagonistic selection was better than synergistic selection in changing GY/P mean. The OG of the one cycle of selection from the F4 generation under both environments was mostly better than the three cycles started from F2 generation. Furthermore, the 10 selected families from the F4 traced back to different F2 plants from the 10 selected families after three cycles under both environments, indicating no correlation between GY/P of the individual plants in the F2 and in the F4 families. The results suggest delaying selection for GY/P to F4 and F5 generations until the recombinants reached acceptable level of homozygosity, to save efforts and expenses. Antagonistic selection for GY/P (under drought stress) was better than synergistic selection (under normal irrigation) in decreasing sensitivity to environments of the selected families.

ABSTRACT The present article was carried out for four seasons to study the relative merits of pedigree selection for days to heading (DH) restricted by grain yield/plant (GY/P) under drought stress and normal irrigation environments to compare three cycles of selection started in the F2 to the F5 with one cycle started in the F4-generation, and to study the sensitivity of the selected families to environments, in addition to monitoring TaELF3 gene expression in bread wheat. The reduction % in DH in the F2 caused by drought stress was 5.1 compared to 2.8 and 3.29% for the two parents Sids4 and Giza164; respectively. The phenotypic (PCV)and genotypic(GCV) coefficients of variability decreased from 5.15 and 4.08% in the F2 to 1.72 and 1.64% after cycle3 under drought stress, and from 6.14 and 2.1% in the F2 to 3.73 and 3.71% after cycle3 under normal irrigation; respectively. The realized heritability increased from 68.15% in cycle1 to 70.5% in cycle3 under drought stress, and from 80.45 to 88.40% under normal irrigation for the respective cycles. The observed genetic gain (OG) in DH of C3 drought selected families was -5.31 and -5.06% (P≤0.01) of the bulk sample, compared to -7.29 and -6.24% for normal irrigation selected families, when evaluation was practiced under drought stress and normal irrigation; respectively. Realized heritability of DH under normal irrigation (antagonistic selection) increased from 68.15 % in cycle1 to 70.5% in cycle3 under drought stress, and from 80.45 to 88.40% under normal irrigation for the respective cycles. The observed genetic grain (OG) in DH of C3 drought selected families was -5.31 and -5.065 (P≤0.01) of the bulk sample, compared to -7.29 and -6.24% for normal irrigated selected families, when evaluation practiced under drought stress and normal irrigation; respectively. Selection for DH under normal irrigation (antagonistic selection) was better than under drought stress (synergistic selection). The results indicated that one cycle of selection for DH started in F4 was equal or better than three cycles started in F2, especially under normal irrigation. The results suggested delaying selection for DH to the F4 or F5 till the recombinants reached acceptable level of homozygosity to save efforts and expenses. The correlated gain in GY/P after three cycles under drought stress was 10.92 and 10.0%, and was 14.94 and 12.36% after one cycle from the F4, while it was 22.18 and 21.20% after three cycles under normal irrigation, and 24.97 and 23.97% after one cycle from F4, from the bulk sample and the better parent; respectively. The other correlated gains were discussed. The relative merits of selection for DH indicated that selection for DH under normal irrigation (antagonistic selection) was better than selection under drought stress (synergistic selection) in changing the mean. qRT-PCR was used to test the expression levels of the TaELF3 gene, responsible for the early flowering in T. aestivum, under both normal irrigation and drought stress conditions, confirming that drought stress enhanced the expression TaELF3 gene and reduced the required days to heading.

ABSTRACT The present article was carried out for four seasons to study the relative merits of pedigree selection for days to heading (DH) restricted by grain yield/plant (GY/P) under drought stress and normal irrigation environments to compare three cycles of selection started in the F2 to the F5 with one cycle started in the F4-generation, and to study the sensitivity of the selected families to environments, in addition to monitoring TaELF3 gene expression in bread wheat. The reduction % in DH in the F2 caused by drought stress was 5.1 compared to 2.8 and 3.29% for the two parents Sids4 and Giza164; respectively. The phenotypic (PCV)and genotypic(GCV) coefficients of variability decreased from 5.15 and 4.08% in the F2 to 1.72 and 1.64% after cycle3 under drought stress, and from 6.14 and 2.1% in the F2 to 3.73 and 3.71% after cycle3 under normal irrigation; respectively. The realized heritability increased from 68.15% in cycle1 to 70.5% in cycle3 under drought stress, and from 80.45 to 88.40% under normal irrigation for the respective cycles. The observed genetic gain (OG) in DH of C3 drought selected families was -5.31 and -5.06% (P≤0.01) of the bulk sample, compared to -7.29 and -6.24% for normal irrigation selected families, when evaluation was practiced under drought stress and normal irrigation; respectively. Realized heritability of DH under normal irrigation (antagonistic selection) increased from 68.15 % in cycle1 to 70.5% in cycle3 under drought stress, and from 80.45 to 88.40% under normal irrigation for the respective cycles. The observed genetic grain (OG) in DH of C3 drought selected families was -5.31 and -5.065 (P≤0.01) of the bulk sample, compared to -7.29 and -6.24% for normal irrigated selected families, when evaluation practiced under drought stress and normal irrigation; respectively. Selection for DH under normal irrigation (antagonistic selection) was better than under drought stress (synergistic selection). The results indicated that one cycle of selection for DH started in F4 was equal or better than three cycles started in F2, especially under normal irrigation. The results suggested delaying selection for DH to the F4 or F5 till the recombinants reached acceptable level of homozygosity to save efforts and expenses. The correlated gain in GY/P after three cycles under drought stress was 10.92 and 10.0%, and was 14.94 and 12.36% after one cycle from the F4, while it was 22.18 and 21.20% after three cycles under normal irrigation, and 24.97 and 23.97% after one cycle from F4, from the bulk sample and the better parent; respectively. The other correlated gains were discussed. The relative merits of selection for DH indicated that selection for DH under normal irrigation (antagonistic selection) was better than selection under drought stress (synergistic selection) in changing the mean. qRT-PCR was used to test the expression levels of the TaELF3 gene, responsible for the early flowering in T. aestivum, under both normal irrigation and drought stress conditions, confirming that drought stress enhanced the expression TaELF3 gene and reduced the required days to heading.

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