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The lentil improvement program of ICARDA benefits from the information generated by the Legume International Nursery Network operating globally. Over the period 1996 to 2002, 12 different types of trials comprising lentil genotypes with weights doi: 10.2135/cropsci2009.06.0342

A good understanding of how the target environments for a breeding program differentiate the germplasm with respect to yield is crucial and allows plant breeders to better target their germplasm. To determine the relationships among high rainfall yield testing locations, yield data from 8 yr of CIMMYT's High Rainfall Wheat Yield Trial (HRWYT) were analyzed by shifted multiplicative model (SHMM) and incremental sum of squares (ISS) classification analyses to group sites within and across years. In the cumulative cluster analysis, about half of the sites clustered into a group characterized by increasing temperature toward maturity. The SHMM analysis identified several sites with high overall association with other sites around the world, and which can be considered as good predictors of global yield performance within the high rainfall megaenvironment. These are autumn-sown locations, which fall into the biggest group of the cumulative cluster analysis with increasing temperature during the growing season. On the other hand, remarkably low associations with global yield ranking were shown for Sta. Catalina (Ecuador) and CIMMYT's primary high rainfall yield-testing location at Toluca (Mexico), which in contrast experience decreasing temperatures toward maturity. Although excellent sites for disease screening, this analysis shows that they do not associate well with the world's high rainfall wheat growing areas for yield., THE BREAD WHEAT BREEDING PROGRAM of the International Maize and Wheat Improvement Center (CIMMYT) breeds spring wheat lines for all major wheat growing areas in the developing world (Rajaram and [...]

Understanding the way different environments differentiate cultivars for yield allows the plant breeder to optimize choice of parents, germplasm screening, yield testing, and resource use within the target region. To determine the associations among yield testing environments, wheat (Triticum aestivum L.) yield data from 963 replicated trials sown across a 20-yr period were analyzed by means of pattern analysis and the shifted multiplicative model (SHMM) to group sites within and across years. Pattern analysis identified four primary clusters of sites and four representative locations within these dusters were identified by squared Euclidean distances. Group-1 represented primarily Mediterranean and West Asian locations and South American sites. Group-2 was comprised of generally warmer sites in southern and eastern Asia. Group-3 comprised higher rainfall locations in South America and eastern Africa and Group-4 represented cooler sites in South America and West Asia. The respective key locations for each of the four groups were Sakha, Egypt; Quezaltenango, Guatemala; Londrina, Brazil; and Pirsabak, Pakistan. The four key sites were then used to examine site clusters within each year by SHMM. The sites at Pirsabak and Sakba associated best across all global wheat-growing regions where a combined total of 700 of 1117 (62%) possible clusters with other global wheat locations were realized. This compared with 52% for Quezaltenango and 38% for Londrina. Factors with a primary influence on site clustering were cropping season moisture availability and temperature. Genotype performance at Pirsabak and Sakha can be used to enhance genetic progress in a range of related wheat growing environments thereby improving the effectiveness of global wheat breeding., THE BREAD WHEAT BREEDING PROGRAM at the International Maize and Wheat Improvement Center (CIMMYT) develops spring wheat germplasm for the wheat production environments of developing countries. Much of this germplasm [...]

Leaf rust, caused by Puccinia recondita Roberge ex Desmaz., is an important disease of wheat (Triticum aestivum L.) worldwide. To estimate the genetic progress in reducing grain yield losses through breeding for resistance to leaf rust, replicated trials including 15 popular CIMMYT germplasm-derived wheat cultivars released between 1966 and 1988 in northwestern Mexico were sown in that same area; normal and late planting dates were used for four and two seasons, respectively. Leaf rust epidemics were established by inoculating spreader rows planted adjacent to plots of the cultivars which were not protected by fungicide. Average losses in grain yields of the cultivars due to leaf rust ranged between 6.6 and 62.7% and were highly correlated with final disease severity (r = 0.898, P [is less than] 0.01) and relative area under the disease progress curve (r = 0.917, P [is less than] 0.01). The losses in grain yield were mostly due to reductions in kernel weight, kernels per square meter, and grain fill rate. Grain yield losses (7.710.4%) in slow rusting cultivars Cocoraque 75, Nacozari 76, Opata 85, and Bacanora 88 were similar to those observed in the immune `Oasis 86' (6.6%) or resistant `Ciano 79' (10.2%). The average annual progress in grain yield potential achieved through breeding averaged over the six trials was estimated to be 0.48% ([r.sup.2] 0.38, P [is less than] 0.01) for fungicide protected and 2.21% ([r.sup.2] = 0.47, P [is less than] 0.01) when not protected by fungicide. We conclude that while the grain yield potential of CIMMYT-derived cultivars has increased significantly over the years, progress in protecting this yield potential through the incorporation of genes that confer slow rusting resistance has been more dramatic., SPRING BREAD WHEAT CULTIVARS derived from germplasm developed by the International Maize and Wheat Improvement Center (CIMMYT) are currently grown on [is greater than] 50.7 million hectares worldwide (Dalrymple, 1986). [...]

In hexaploid wheat (Triticum aestivum L.) disease resistance genes transferred from alien sources are often associated with undesirable traits. Replicated trials using near-isogenic lines of spring wheat `Seri 82' were conducted for 2 yr under non-moisture stress and simulated moisture stress conditions to determine the effects of the 7DL.7Ag and 1BL.1RS translocations [from Agropyron elongatum (Host) Beauv. and Secale cereale L., respectively] on grain yield and related traits. Mean grain yield of the 1B lines was significantly higher (3.2%) than that of the 1BL.1RS translocation lines in non-moisture stress trials, but not significantly higher in the moisture stress trials. The mean grain yields of the rive highest yielding reconstituted Seri 82 genotypes (1BL.1RS) were significantly lower than that of the genotypes without the 1BL.1RS translocation in non-moisture stress (3.2%) and moisture stress (5.2%) conditions. Incorporation of the 7DL.7Ag translocation caused a significant increase (9%) in biomass at harvest in non-moisture stress trials. The mean grain yields of the rive highest yielding 7DL.7Ag lines were significantly higher (8.2%) than the reconstituted Seri 82 genotypes in non-moisture stress conditions and more than 16% lower under moisture stress. Lower grain yields of the 7DL.7Ag lines under moisture stress could be due to their excessive pre-heading biomass production. Several yield-related traits of the near-isogenic genotypes varied significantly. Presence of each translocation caused lateness and, when present together, the 1BL.1RS and 7DL.7Ag translocations delayed heading and maturity by 7 and 5 d, respectively. The genetic background of the recipient wheat can affect the utility of a translocation., Rust diseases of wheat are important production constraints in most wheat growing areas worldwide (Roelfs et al., 1992). Use of genetic resistance is the most economic and environmentally sound measure [...]

The adaptation and performance of CIMMYT's bread wheat germplasm (Triticum aestivum L.) under conditions of low N fertility have been questioned because they were developed under medium-high levels of N fertility. The objectives of this research were to (i) compare the performance of a set of tag vs. semidwarf cultivars developed by CIMMYT that were widely grown by farmers in the Yaqui Valley of Mexico at low and high N fertility, (ii) measure the genetic progress in grain yield and N use efficiency (NUE), and (iii) evaluate the contribution of N uptake efficiency (UPE) and utilization efficiency (UTE) to NUE. Ten wheat cultivars, two tall and eight semidwarf, produced by CIMMYT and released in the Yaqui Valley of Sonora, by the Mexican government from 1950 to 1985 were grown with 0, 75, 150, or 300 kg N [ha.sup.-1] in a 3-yr field study at Ciudad Obregon, Sonora, Mexico. Genetic gains in both grain yield and NUE during 1950 to 1985 were 1.1, 1.0, 1.2, and 1.9% [yr.sup.-1] on a relative basis or 32, 43, 59, and 89 kg [ha.sup.-1] [yr.sup.-1] on an absolute basis, when provided 0, 75, 150, and 300 kg [ha.sup.-1] N, respectively. Progress in NUE resulted in an improvement of both UPE and UTE. However, the relative importance of these two components was affected by the level of applied N. These results contradict the belief that modern semidwarf cultivars require more N than older cultivars. Instead, they respond more to N, which translates into higher economic rates and how returns when N fertilizer is available., Cimmyt's bread wheat breeding program has selected and tested lines and cultivars under medium-high N fertilizer levels (120 to 200 kg [ha.sup.-1] N) since the 1960s, a practice that has [...]

Wheat (Triticum aestivum L.) breeders often try to simultaneously improve grain yield and bread-making quality. This study examined changes in CIMMYT's wheat germplasm with respect to grain protein concentration (GPC)-and grain protein quality (GPQ)-related parameters and assessed the importance of these parameters in determining bread-making quality, when wheat cultivars were grown with 0, 75, 150, or 300 kg N [ha.sup.-1]. A 3-yr field study was established with 10 cultivars representing breeding progress from 1950 to 1985. Floor protein concentration (FPC), sodium dodecyl sulfatese-dimentation (SDS-S), alveogram W (ALVW), alveogram P/G (ALVPG), bread loaf volume (LV), and GPC were evaluated. At low N (0 and 75 kg [ha.sup.-1]), there was no difference in GPC among cultivars. In contrast, at higher N (150 and 300 kg [ha.sup.-1]), there was a linear reduction in GPC with respect to the year of release. However, when the two tall, older cultivars and cv. Siete Cerros 66, an outlier, were removed from the analysis, there was a negative trend between GPC and year of release but only at the 300 kg N [ha.sup.-1] level. There was no How trend in year of release for GPQ parameters or LV. Loaf volume was most consistently correlated with SDS-S across the different levels of N compared with GPC, FPC, ALVW, or ALVPG. However, GPC and LV showed a highly significant correlation only when the two soft wheat cultivars were removed from analysis. Use of semidwarf germplasm in CIMMYT's wheat breeding program initially resulted in increased grain yield and reduced GPC. However, during the period of semidwarf improvement, increasing grain yield was possible while maintaining GPC, except under high levels of N application., From 1950 to 1985, spring bread wheat breeders at CIMMYT considered grain yield as their primary objective. Bread-making quality received attention throughout this period, particularly in the 1960s. As a [...]

Germplasm from the spring wheat (Trificum aestivum L.) breeding program at the International Center for Improvement of Maize and Wheat (CIMMYT) has had a major impact on the yield of irrigated spring wheats in most developing countries in the past 30 yr. The rate and nature of yield potential progress in this germplasm was measured comparing eight outstanding short cultivars released in northwest Mexico between 1962 and 1988. They were grown under irrigation and optimal management, including disease and lodging protection, in each of six winter growing seasons (1989-1990 to 1994-1995) at the CIANO (Centro de Investigaciones Agricolas del Noroeste) experiment station in Sonora, Mexico. There were highly significant effects of cultivar on grain yield, and, although cultivar x year interaction was significant, there were few significant crossover interactions between pairs of genotypes and years in the grain yield data set. Yield averaged across the 6 yr increased linearly from 6680 kg [ha.sup.-1] for the earliest cultivar, Pitic 62, to 8475 kg [ha.sup.-1] for Bacanora 88, the latest. The rate of progress against year of release was 67 kg ha1 [yr.sup.-1] (r = 0.99, P [is less than] 0.001), or 0.88% per year. Grain yield progress was correlated with kernel number per square meter (r = 0.84, P [is less than] 0.01) and harvest index (r = 0.81, P [is less than] 0.02), but not with total biomass production, kernel weight, days to anthesis, spikes per square meter, or kernels per spike. Thus linear progress in yield within short germplasm has continued at least until the late 1980s, and the yield components studied did not indicate any clear direction for future progress, apart from that suggested by the strong relationships between grain yield and harvest index and grain yield and kernels per square meter, as has been seen in most studies of yield progress in cereals., Sring-habit bread wheat germplasm, selected in Mexico by CIMMYT, has had a major impact on composition of cultivars grown in developing countries (Byerlee and Moya, 1993). Besides multiple disease resistance [...]

A key question in genetic improvement of yield under drought stress is how to choose environments to evaluate and identify genotypes that yield well under drought. The objective of this study was to compare various moisture regimes as evaluation environments for wheat (Triticum aestivum L. emend. Thell.) germplasm, based on performance of specific genotypes and on expected genetic advance from direct and indirect selection. The test included 12 new, experimental spring bread wheat genotypes selected for high yield under both full and reduced irrigation in Mexico and four cultivars selected in and adapted to each of the following moisture regimes: (i) full irrigation (FI), (ii) late season drought (LD), (iii) early season drought (ED), (iv) residual moisture (RM), and (v) sporadic drought. All genotypes were yield tested for 2 yr under four moisture regimes: (i) FI (five irrigations), (ii) LD (two early season irrigations), (iii) ED (one early and two late season irrigations), and (iv) RM (one early season irrigation). Estimates of expected selection response indicated that indirect selection under FI would result in greater yield gains under drought than would direct selection in any of the drought environments. However, under all drought conditions, certain of the new, experimental genotypes produced yields that were numerically, though not always statistically, higher than genotypes selected only under FI. Evaluation under both optimum and drought conditions appears to be an effective method to take advantage of the increased selection response under FI while preserving alleles for high yield under drought.

Wild relatives of wheat (Triticum aestivum L.) have primarily been used as sources of genes for biotic and abiotic stress resistance. A more direct approach to grain yield improvement has been sought by using exotic germplasm to enhance quantitative traits, including grain yield. This study was conducted to determine whether synthetic hexaploids, developed from artificial hybridization of durum wheat [Triticum turgidum ssp. durum (Desf.) Husn.] with Aegilops tauschii Coss., can enhance yield or yield components of wheat. Two hundred eighty-two [BC.sub.2][F.sub.2]-derived lines, involving six crosses between different synthetic hexaploids and four spring wheat cultivars, were evaluated for grain yield and its components. These synthetic-derived lines were compared with their recurrent parent in field experiments conducted during the 1995 to 1996 and 1996 to 1997 crop seasons near Ciudad Obregon, Sonora, Mexico. More than 80% of the synthetic-derived lines were significantly superior to their recurrent parent for kernel weight. Eight lines had significantly higher grain yield compared with their recurrent parent. Grain yields of superior lines were up to 11% higher than those of their recurrent parents. A strong association between grains [m.sup.-2], biomass, spikes [m.sup.-2], and grain and biomass production rates and grain yield was observed in all populations. Path coefficient analyses of yield components revealed a strong direct effect of spikes [m.sup.-2] and grains [spike.sup.-1] on grain yield. Results indicate that synthetic hexapioids can be a valuable source of alleles to improve kernel weight., MODERN HEXAPLOID WHEAT originated from a series of natural hybridizations between the wild diploids (2n = 2x = 14) Triticum urartu Tumanian ex Gandilyan, A genome (Chapman et al., 1976; [...]

`Siglo TCL-21', spring triticale (X triticosecale Wittmack L.) (Reg. no. CV- 20, PI 6131611) was developed by the International Maize and Wheat Improvement Center, (CIMMYT), Mexico D. F., Mexico, and [...]

`Milenio TCL-3', spring triticale (X triticosecale Wittmack L.) (Reg. no. CV-19, PI 613158) was developed by the International Maize and Wheat Improvement Center (CIMMYT), Mexico D.F., Mexico, and released in [...]

`Quebrantahuesos-TCL99', spring triticale (X triticosecale Wittmack L.) (Reg. no. CV-18, PI 613159) was developed by the International Maize and Wheat Improvement Center (CIMMYT), Mexico D.F., Mexico, and released in Mexico [...]

`Supremo TCL-2000,' spring triticale (X triticosecale Wittmack L.) (Reg. no. CV-23, PI 613157) was developed by the International Maize and Wheat Improvement Center (CIMMYT), Mexico D.F., Mexico, and released in [...]

`Cerrillo-TCL99' spring triticale (X triticosecale Wittmack L.) (Reg. no. CV-22, PI 613156) was developed by the International Maize and Wheat Improvement Center (CIMMYT), Mexico D.F., Mexico, and released in Mexico [...]

`Maravilla-TCL99' spring triticale (X triticosecale Wittmack L.) (Reg. no. CV-21, PI 613160) was developed by the International Maize and Wheat Improvement Center (CIMMYT), Mexico D.F., Mexico, and released in Mexico [...]

Wild ancestors of common wheat (Triticum aestivum L.) have been reported to have higher maximum photosynthetic rates than modern wheat cultivars. Synthetic hexaploids, obtained by crossing tetraploid wheat and Aegilops tauschii Cuss., have proven useful as a source of resistance or tolerance to biotic and abiotic stresses. This study was conducted to determine whether synthetic hexaploids also could contribute genetic diversity to enhance leaf photosynthetic rate and other physiological traits. Three different populations of [BC.sub.2][F.sub.2:6] synthetic-derived lines were evaluated at the Agricultural Research Center for the Northwest (INIFAP) Experimental Station, near Ciudad Obregon, Sonora, Mexico. Differences in maximum photosynthetic rate were detected among genotypes. Several synthetic-derived lines showed higher photosynthetic rates than their recurrent parent. Staygreen, determined as days between senescence and physiological maturity, of most synthetic-derived lines did not differ from the recurrent parents. Maximum photosynthetic rate was negatively associated with leaf area and positively associated with stomatal and mesophyll conductances, and leaf temperature depression. Mesophyll conductance accounted for 85% of the variation in maximum photosynthetic rate. These results suggest that synthetic-derived wheat can be also a source of genetic diversity for important physiological traits such as enhanced photosynthetic rate., COMMON WHEAT is an allopolyploid species that originated from hybridization between wild diploids having the A, B, and D genomes. Evolution and artificial selection have modified morphological and physiological traits, [...]

Global demand for wheat (Triticum aestivum L.) is growing faster than gains in genetic yield potential are being realized, currently a little under 1% per year in most regions. Improvement in yield of semidwarf wheat has generally been associated with increased harvest index (HI) and grain per square meter. For CIMMYT (International Maize and Wheat Improvement Center) varieties released between 1962 and 1988, yield increase was also associated with higher flag-leaf photosynthetic rate and related traits, but not higher biomass. Nevertheless, significantly higher biomass has been reported in more recent CIMMYT lines. Improved HI is associated with higher N use efficiency (yield per unit of available N) and improved yield of semidwarf lines is expressed at high and low levels of N input. Where interplant competition for light and soil factors are manipulated, yield improvement is associated with adaptation to high plant density. Studies have confirmed that the juvenile spike growth phase is critical in determining both grain number and kernel weight (sink) potential. Improving assimilate availability during this stage, perhaps by lengthening its relative duration, may be one way to improve yield potential. Traits that could potentially be exploited for improving assimilate (source) capacity include early vigor, stay-green, leaf-angle, and remobilization of stem reserves. Use of alien chromatin is a successful approach for introducing yield-enhancing genes into elite genetic backgrounds. Examples include the 1B/1R chromosome translocation from rye (Secale cereale L.), and more recently the LR19 segment from tall wheatgrass [Agropyron elongatum (Host) P. Beauv.] Improving the efficiency of early-generation selection may be another strategy for raising yield potential by increasing the probability of identifying physiologically superior lines by techniques such as infrared thermometry and spectral reflectance., WHEAT PROVIDES more than one-quarter of the total world cereal output, and constitutes the main source of calories for more than 1.5 thousand million people. The crop is grown on [...]

PBATM96 (Poblaci6n Base Androesteril de Trigos Mexicanos 1996) germplasm (Reg. no. GP-499, PI 603214) is a male-sterile based population of Mexican spring wheat (Triticum aestivum L.) that was developed with [...]