The main elements of the international wheat improvement program of the Centro Internacional de Mejoramiento de Maiz y Trigo (CIMMYT), also known as the International Maize and Wheat Improvement Center, have been shuttle breeding at two contrasting locations in Mexico, wide adaptation, durable rust and Septoria resistances, international multisite testing, and the appropriate use of genetic variation to enhance yield gains of subsequently produced lines. Such an approach yielded successes known collectively as the Green Revolution. However, at the beginning of the 21st century, this “cultivar assembly line” approach needs fine tuning to address crop needs under increasingly adopted resource conserving practices, as well as those related to nutritional requirements of the end-users. International wheat improvement will therefore focus on the targeting of traits in respective mega-environments, and the use of participatory methods, especially in marginal environments. The main features of this wheat improvement strategy include the introduction of new and novel sources of genetic variation through wild species, landraces, and, potentially, the use of transgenes for intractable traits. This variation will be combined using international shuttle breeding, and increased breeding efficiency will be achieved through marker-aided methods, more targeted use of crop physiology, plant genetics, biostatistics, and bioinformatics. Likewise, CIMMYT will increase its focus on the needs of end-users by emphasizing regional efforts in participatory research and client-oriented plant breeding.

High yield potential, shuttle breeding, genetic diversity, and a new international wheat improvement strategy

Emmer wheat (Triticum dicoccon Schrank, 2n = 4x = 28) consists in a hulled wheat; its cultivation has been drastically reduced during the last century as a consequence of its low yield. Recently, its agronomic and nutritive values, as well as the increase of popularity of organic agriculture, have led to a renewed interest making its cultivation economically viable in the marginal lands with an increase of the cultivated areas. In Italy, it mainly survives in few marginal lands of central and southern Italy, where local varieties, adapted to the natural environment from where they originate, are used; moreover, some selected lines have also been developed. In the present work, agro-morphological and qualitative traits, together with molecular analyses of 20 emmer accessions consisting of Italian landraces, breeding lines, and cultivars, were performed. The field experiments were conducted for two consecutive years (2001/2002–2002/2003) in two locations: Viterbo in central Italy, and Foggia in south Italy. The analyzed emmer wheat accessions showed a good amount of genetic variability for both evaluated agro-morphological and molecular traits. This study illustrates an increase in earliness, GY, TW, TKW, and YI going from landraces, breeding lines to cultivars, while the variability does not change proportionally.

Agronomical, quality, and molecular characterization of twenty Italian emmer wheat (Triticum dicoccon) accessions

One of the major breeding objectives for watermelon (Citrullus lanatus [Thumb.] Matsum & Nakai) is improved fruit yield. High yielding genotypes have been identified, so we measured their stability for fruit yield and yield components over diverse environments. The objectives of this study were to (i) evaluate the yield of watermelon genotypes over years and locations, (ii) identify genotypes with high stability for yield, and (iii) measure the correlations among univariate and multivariate stability statistics. A diverse set of 40 genotypes was evaluated over 3 yr (2009, 2010, and 2011) and eight locations across the southern United States in replicated trials. Yield traits were evaluated over multiple harvests, and measured as marketable yield, fruit count, percentage cull fruit, percentage early fruit, and fruit size. There were strong effects of environment as well as genotype  ́ environment interaction (G ́E) on watermelon yield traits. Based on multiple stability measures, genotypes were classified as stable or unstable for yield. There was an advantage of hybrids over inbreds for yield components in both performance and responsiveness to favorable environments. Cultivars Big Crimson and Legacy are inbred lines with high yield and stability. A significant (P < 0.001) and positive correlation was measured for Shukla’s stability variance (si 2), Shukla’s squared hat (ŝi 2), Wricke’s ecovalence (Wi), and deviation from regression (Sd) for all the traits evaluated in this study. M. Dia and T.C. Wehner, Dep. of Horticultural Science, North Carolina State Univ., Campus Box 7609, Raleigh, NC 27695-7609; R. Hassell, Clemson University, Coastal Research and Education Center, 2700 Savannah Hwy, Charleston, SC 29414; D.S. Price, Georgia County Extension, SW District, 110 West 13th Ave, Suite C, Cordele, GA 31015; G.E. Boyhan, University of Georgia, Dep. of Hort., 1111 Miller Plant Science Bldg., Athens, GA 30602; S. Olson, North Florida REC, Univ. of Florida, 155 Research Road, Quincy, FL 32351-5677; S. King, Texas A&M University, Dep. of Hort. Sci., 1500 Research Pkwy, Ste A120, College Station, TX 77845; A.R. Davis, USDA-ARS, 911 East Highway 3, Lane, OK 74555; G.E. Tolla, Monsanto/Seminis Veg Seeds, 37437 State Hwy 16, Woodland, CA 95695. Received 12 Oct. 2015. Accepted 2 Feb. 2016. *Corresponding author (tcwehner@gmail.com). Abbreviations: AEC, average environment coordinate; AMMI, additive main effects and multiplicative interaction; bi, linear regression coefficient; CI, Clinton, NC; FL, Quincy, FL; GA, Cordele, GA; GGE, genotype main effects plus genotypic  ́ environment interaction effect; GGL, genotype main effects plus genotypic  ́ location interaction effect; G ́E, Genotype  ́ environment interaction; G01 or 1, AU-Jubilant; G02 or 2, Allsweet; G03 or 3, Big Crimson; G04 or 4, Black Diamond; G05 or 5, Calhoun Gray; G06 or 6, Calsweet; G07 or 7, Carolina Cross#183; G08 or 8, Charleston Gray; G09 or 9, Congo; G10 or 10, Crimson Sweet; G11 or 11, Desert King; G12 or 12, Early Arizona; G13 or 13, Early Canada; G14 or 14, Fiesta F1; G15 or 15, Georgia Rattlesnake; G16 or 16, Golden Midget; G17 or 17, Graybelle; G18 or 18, Hopi Red Flesh; G19 or 19, Jubilee; G20 or 20, King & Queen; G21 or 21, Legacy; G22 or 22, Mickylee; G23 or 23, Minilee; G24 or 24, Mountain Hoosier; G25 or 25, NC Giant; G26 or 26, Navajo Sweet; G27 or 27, Peacock WR-60; G28 or 28, Quetzali; G29 or 29, Regency F1; G30 or 30, Royal Flush F1; G31 or 31, Sangria F1; G32 or 32, Starbrite F1; G33 or 33, Stars-N-Stripes F1; G34 or 34, Stone Mountain; G35 or 35, Sugar Baby; G36 or 36, Sugarlee; G37 or 37, Sweet Princess; G38 or 38, Tendersweet OF; G39 or 39, Tom Watson; G40 or 40, Yellow Crimson; KN, Kinston, NC; M, trait mean; OK, Lane, OK; PC, principal component; SC, Charleston, SC; SVP, singular value partitioning; TX, College Station, TX; CA, Woodland, CA; si 2, Shukla’s stability variance; Ŝi 2, Shukla’s squared hat; Sd, deviation from regression; Wi, Wricke’s ecovalence; YSi, Kang’s stability statistic Published in Crop Sci. 56:1645–1661 (2016). doi: 10.2135/cropsci2015.10.0625 © Crop Science Society of America | 5585 Guilford Rd., Madison, WI 53711 USA All rights reserved. Published June 15, 2016

Genotype × Environment Interaction and Stability Analysis for Watermelon Fruit Yield in the United States

Seventeen hybrid maize genotypes were evaluated at four locations (Yeniehir- Marmora Region; Bornova-Aegean Region; Ceyhan-Mediterranean Region; Seyhan- Mediterranean Region) in 2005 and 2006 cropping seasons under irrigated conditions in Turkey. The analysis of variance for grain yield of the 17 hybrid genotypes tested in eight environments showed mean squares of environments, genotypes and GEI (genotype x environment interaction) were highly significant and accounted for 62.1%, 12.5% and 25.4% of treatment combination sum of squares, respectively. To determine the effects of GEI on yields, the data were subjected to additive main effects and multiplicative interaction (AMMI) and the GGE biplot analysis. Although mean grain yield of the check cultivar G12 was higher than those of experimental hybrids, difference between G12 and G16, which is the most stable genotype according to AMMI and GGE biplot, was insignificant. It is understood that the experimental hybrid maize G16 can be proposed in reliably for growing by the farmers. Also, it was detected that only the test environment E3 (Ceyhan location) may be sufficient for deciding about which experimental hybrids can be recommended, instead of four test locations (Ceyhan, Seyhan, Bornova and Yeniehir) in this study. In addition, it is concluded that there is no difference between the AMMI and GGE biplot analysis in evaluation of experimental maize hybrids and test environments in this research and that both methods can be used successfully in determining suitable locations for maize hybrids in the environments under Mediterranean climate conditions.

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Assessment of Genotype X Enviroment Interactions for Grain Yield in Maize Hybrids Using Ammi and GGE Biplot Analyses

Lycopene is a naturally occurring red carotenoid compound that is found in watermelon. Lycopene has antioxidant properties. Lycopene content, sugar content and hollowheart resistance are subject to significant genotype×environment interaction (G×E), which makes breeding for these fruit quality traits difficult. The objectives of this study were to (i) evaluate the influence of years and locations on lycopene content, sugar content and hollowheart resistance for a set of watermelon genotypes, and (ii) identify genotypes with high stability for lycopene, sugar, and hollowheart resistance. A diverse set of 40 genotypes was tested over 3 years and 8 locations across the southern United States in replicated, multi-harvest trials. Lycopene was tested in a subset of 10 genotypes. Data were analyzed using univariate and multivariate stability statistics (BLUP-GGE biplot) using SASGxE and RGxE programs. There were strong effects of environment as well as G×E interaction on watermelon quality traits. On the basis of stability measures, genotypes were classified as stable or unstable for each quality trait. 'Crimson Sweet' is an inbred line with high quality trait performance as well as trait stability. 'Stone Mountain', 'Tom Watson', 'Crimson Sweet' and 'Minilee' were among the best genotypes for lycopene content, sugar content and hollowheart resistance. We developed a stability chart based on marketable yield and average ranking generated from different stability measures for yield attributes and quality traits. The chart will assist in choosing parents for improvement of watermelon cultivars. See http://cuke.hort.ncsu.edu/cucurbit/wmelon/wmelonmain.html.

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Stability of fruit quality traits in diverse watermelon cultivars tested in multiple environments.

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K. M. Dawod

Papers

Genotype – environment interaction in durum wheat