Isotopic Composition of Plant Carbon Correlates With Water-Use Efficiency of Wheat Genotypes

Variation in carbon-isotope composition among and between wheat genotypes was correlated with variation in water-use efficiency in separate pot experiments conducted in spring-summer and in winter. In the main, winter experiment, the water-use efficiencies ranged from 2.0 to 3.7 mmolC/mol H2O (means of four replicates) while the corresponding isotope effects for leaf material ranged from 1.0225 to 1.0194. 13C was more abundant in grain than in leaves and stems. It is suggested that carbon-isotope analysis may be a useful tool in selection for improved water-use efficiency in breeding programmes for C3 species. [1]

Evaluating salt tolerance of wheat genotypes using multiple parameters

Salt tolerance of wheat is known to change with growth stage. Identifying the multiple parameters associated with salt tolerance during different growth stages is important for evaluating wheat genotypes and improving their salt tolerance. Thirteen wheat genotypes from Egypt, Germany, Australia and India were grown in soil and exposed to four salinity levels (control, 50, 100 and 150 mM NaCl). Tiller number, leaf number and leaf area per plant at vegetative stage; dry weight per plant at vegetative, reproductive and maturity stages; and yield components of main spike and total grain yield at maturity were determined. The results showed that tiller number was affected more by salinity than leaf number and leaf area at the vegetative stage. Salinity decreased dry weight per plant significantly at all growth stages. Spikelet number on the main stem decreased much more with salinity than spike length, grain number and 1000-grain weight at maturity. According to cluster analysis with multiple agronomic parameters at all growth stages, the Egyptian genotypes Sakha 8 and Sakha 93 and the Indian genotype Kharchia were ranked as the most tolerant to salinity. A change in salt tolerance with growth stages was observed for Sids 1, Gemmeza 7 and Westonia. Drysdale and Sakha 69 were ranked as moderate tolerant. The remaining genotypes showed the lowest tolerance to salinity at all growth stages. We conclude that an increase in tiller number per plant and spikelet number per spike will improve the salt tolerance of wheat genotypes in breeding programs. Cluster analysis with multiple agronomic parameters simultaneously to evaluate the salt tolerance facilitates the rankings of salt tolerance of wheat genotypes. [2]

Genotype and Environment Effects on Quality Characteristics of Hard Red Winter Wheat

Improvement of end‐use quality in wheat (Triticum aestivum L.) depends on thorough understanding of the influences of environment, genotype, and their interaction. Our objectives were to determine relative contributions of genotype, environment, and G × E interaction to variation in quality characteristics of hard red winter wheat. Eighteen winter wheat genotypes were grown in replicated trials at six locations in Nebraska and one site in Arizona in 1988 and 1989. Harvested grain was micromilled to produce flour samples for evaluation of protein concentration, mixing characteristics, and sodium dodecylsulfate (SDS) sedimentation. Kernel hardness was determined by microscopic evaluation of individual kernels. Genotype, environment, and interaction effects were found to significantly influence variation in all quality parameters. Variances of quality characteristics associated with environmental effects were generally larger than those for genetic factors. The magnitude of G × E effects were found to be of similar magnitude to genetic factors for mixing tolerance and kernel hardness, but were smaller for flour protein concentration, mixing time, and SDS sedimentation value. Significant differences among genotype responses (b‐values) were observed in the regressions of genotype mean on location means for each quality parameter. There were few instances of significant deviations from regression. Positive correlations between genotype grand mean and genotype b‐values for flour protein, mixing time, and mixing tolerance suggest that simultaneous improvement in both mean and stability for these traits may be difficult. Based on these results, environmental influences on enduse quality attributes should be an important consideration in cultivar improvement efforts toward enhancing marketing quality of hard red winter wheat. [3]

GGE Biplot Analysis of Multi-environment Yield Trials of Durum Wheat (Triticum turgidum Desf.) Genotypes in North Western Ethiopia

This experiment was done to identify the most stable durum wheat genotype(s) as well as desirable environment(s) for durum wheat (Triticum turgidum var. durum Desf.) research in north western Ethiopia. Grain yield performance of the tested genotypes were evaluated at four locations (Adet, Debretabor, Gaint and Simada) using randomized complete block design with three replication for two consecutive years (2010 and 2011). Combined analysis of variance showed that grain yield was significantly affected by environments (E), genotypes (G) and GE interactions. The first two principal components (PC1 and PC2) were used to create a two-dimensional GGE biplot and explained 45.67% and 32.71% of the total sums of squares of GE interaction, respectively. The ‘which-won-where’ feature of the GGE biplot suggested that the existence of three durum wheat mega-environments in north western Ethiopia. Among the testing environments, six environments such as E1, E2, E4, E5, E6 and E8 were included inside mega-environment one (ME1) while the remaining two testing environments, E3 and E7 were included inside mega–environment two (ME2) and mega-environment three (ME3), respectively. The GGE biplot also identified G7, G5 and G10 as winning genotypes at ME1 whereas G11 was identified as a high yielding genotype in both ME2 and ME3. According to the average environment coordination (AEC) views of the GGE-biplot, genotype G10 was identified as the most stable and high yielding genotype. In addition, G1 and G6 also showed better stability performance among the high yielding genotypes whereas genotype G12 was identified as the least stable and low yielding genotype. Therefore, genotypes G10, G1 and G6 were recommended for commercial production in most wheat growing areas of north western Ethiopia. [4]

Field Screening of Wheat (Triticum aestivum L.) Genotypes for Salinity Tolerance at Three Locations in Egypt

Although screening large numbers of wheat genotypes for salinity tolerance under controlled elevated salinity levels in the greenhouse is useful, the final screening in the field at different locations, where soils are naturally affected with salt and other uncontrolled factors in soil and climate interact with salinity, is a must before deciding the most suitable genotype for each location. In the present study, 117 bread wheat doubled haploid (DH) lines derived from the cross Sakha 8 X Line 25, along with their parents and the two check cultivars Sakha 93 and Sids 1 were screened for salinity tolerance under field conditions at three locations and two seasons, i.e. Serw (2011/12), Sakha (2011/12), Sakha (2013/14) and Gemmeiza (2013/14), where ECe was 9.4, 5.7, 5.5 and 2.4 dSm-1, respectively and irrigation water ECw was 0.46 – 0.60 dSm-1. The genotypes were classified into salt tolerant, moderately tolerant, sensitive and very sensitive based on grain yield/ plant. The rank of tolerant genotypes differed from one location to another and from season to season. The ten most tolerant DH lines across all environments were No.19, 44 , 65 , 33 , 24 , 2 , 21 , 98 61 and 99. The best DH line out-yielded the best check by 40.6% at Serw 11/12 (L40), 107.8% at Sakha 2011/12 (L16), 10.2% at Sakha 2013/14 (L2), 28.5% at Gemmeiza 2013/14 (L71) and 48.7% across the four environments (L19). [5]

Reference

[1] Farquhar, G.D. and Richards, R.A., 1984. Isotopic composition of plant carbon correlates with water-use efficiency of wheat genotypes. Functional Plant Biology, 11(6), pp.539-552.

[2] El-Hendawy, S.E., Hu, Y., Yakout, G.M., Awad, A.M., Hafiz, S.E. and Schmidhalter, U., 2005. Evaluating salt tolerance of wheat genotypes using multiple parameters. European journal of agronomy, 22(3), pp.243-253.

[3] Peterson, C.J., Graybosch, R.A., Baenziger, P.S. and Grombacher, A.W., 1992. Genotype and environment effects on quality characteristics of hard red winter wheat. Crop Science, 32(1), pp.98-103.

[4] Abate, F., Mekbib, F. and Dessalegn, Y. (2015) “GGE Biplot Analysis of Multi-environment Yield Trials of Durum Wheat (Triticum turgidum Desf.) Genotypes in North Western Ethiopia”, Journal of Experimental Agriculture International, 8(2), pp. 120-129. doi: 10.9734/AJEA/2015/9994.

[5] Al-Naggar, A. M. M., Sabry, S. R. S., Atta, M. M. M. and El-Aleem, O. M. A. (2015) “Field Screening of Wheat (Triticum aestivum L.) Genotypes for Salinity Tolerance at Three Locations in Egypt”, Journal of Agriculture and Ecology Research International, 4(3), pp. 88-104. doi: 10.9734/JAERI/2015/18920.