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The paper compares food and straw fodder traits in wheat lines of 6 different CIMMYT wheat trials tested across 32 environments of South Asia (India, Nepal, Bangladesh and Pakistan). Experiments were conducted in the main spring wheat season with sowing time of mid-November to mid-December and harvest between March to April. Investigated and compared were grain yield (GY), straw yield (SY), straw nitrogen (N) content, neutral (NDF) and acid (ADF) detergent fiber, acid detergent lignin (ADL), and in vitro organic matter digestibility (IVOMD). Highly significant (P 60%), considerable (45%) for HI and straw N (40%), moderate for ADL (18%), and minor for NDF, ADF, and IVOMD ( Across all cultivar types only ADF was significantly (P 0.05) relationships were observed between N, ADF and IVOMD and SY. Among cultivars consistent relationships were only observed between N and GY which were significantly (P = 0.03 to 0.009) inversely correlated in five out of the six cultivar types. Within cultivars types ADF varied by at least 2.3% units in HTNM and 1st DRYT and up to 4.9% units in ESWYT. By extrapolation such cultivar-dependent differences will matter at wheat straw trading.

Fifty wheat lines targeting semi-arid locations in India and Bangladesh were investigated for grain and straw yield and straw fodder quality traits for two consecutive years at two locations in India and one in Bangladesh. Fodder traits investigated were nitrogen (N), neutral detergent fiber (NDF), acid detergent fiber (ADF), acid detergent lignin (ADL), in vitro organic matter digestibility (IVOMD), and metabolizable energy content (ME). Highly significant (P

‘Slow rusting’ adult plant resistance (APR) genes can provide non-specific durable resistance to leaf rust in wheat. In this study, we phenotyped 120 exotic wheat accessions for slow rusting components and investigated the presence of known APR genes. The tightly linked STS/SSR molecular markers csLV34, Xwmc44, Xcfd71 and csGS respectively for APR genes viz., Lr34, Lr46, Lr67 and Lr68 were used to characterize the wheat accessions. Lr46 was the most frequent (62.5%) followed by Lr67 (43.3%), Lr68 (26.6%) and Lr34 (21.6%). Wheat accessions carrying known APR genes showed a range of disease severity responses, but the severities were significantly lower (R to 60MS) than those of the susceptible checks (80S to 100S), with the exception of some lines carrying Lr46 and Lr67 alone or in combination showed disease severity up to 100S. Accessions such as EC-603897, EC-693258, EC-693262, EC-693285 and EC-693306 carried four known APR genes viz., Lr34, Lr46, Lr67 and Lr68 and provided high levels of resistance with area under disease progress curve (AUDPC) value ranging from 0 to 149.3. These genotypes will serve as useful donors for resistance breeding efforts seeking to develop wheat varieties with durable leaf rust resistance.

Spot blotch (SB) caused by Cochliobolus sativus is a serious biotic stress to wheat in warm and humid areas, particularly South Asia (SA). In order to support South Asian farmers to combat SB, International Maize and Wheat Improvement Center (CIMMYT) established an efficient SB screening system at Agua Fria, Mexico and developed a nursery under the project - Cereal Systems Initiative for South Asia (CSISA). The materials used to form CSISA-SB nursery were selected from advanced breeding lines from different wheat breeding programs at CIMMYT. Seed of CSISA-SB nursery was produced at disease-free plots at El Batan and Mexicali, and distributed to SA after rigorous seed health checks. The 4th CSISA-SB, made available in 2012, comprised 50 entries including two resistant and two susceptible checks. The nursery was evaluated in seven locations in Mexico, India, and Bangladesh in the 2012–13 cropping season. The results indicated that although few lines exhibited stable resistance across locations due to strong G × E interaction, promising lines with SB resistance and good agronomy can still be identified in each location. The two most promising lines showing consistent spot blotch resistance across the regions were CHUKUI#1 (CIMMYT germplasm bank identification number, GID 6178575) and VAYI#1 (GID 6279248). These lines could be promoted as sources of SB resistance or directly released as cultivars in SA.

Marker assisted backcrossing (MABC) was used to transfer the three stem rust ( Puccinia graminis tritici ) resistant genes Sr25 , SrWeb and Sr50 into the popular Indian wheat cv. HUW234. The donor was the CIMMYT breeding line PMBWIR4, and each of the target genes was marked by a simple PCR assay. A three step screening strategy was adopted: the first screen comprised foreground selection, the second used markers lying close to the introgression borders to reduce the extent of linkage drag, and the last was background selection based on 149 informative microsatellite assays. Based on the background selection outcomes, at the BC 1 F 1 generation the proportion of the genome fixed for cv. HUW234 alleles ranged from 55% to 67%. Three BC 1 F 1 individuals were crossed a second time with cv. HUW234, resulting in the identification of six BC 2 F 3 families carrying all three target Sr genes; the proportion of their genome inherited from cv. HUW234 ranged from 86% to 92%. BC 2 F 4 and BC 2 F 5 material was planted at three different locations under both disease-free and artificially induced epiphytotic conditions. Compared to recurrent parent, the improved versions of cv. HUW234 displayed significantly superior resistance to stem rust, and their agronomic performance was as good as, or even marginally better than that of the source cultivar.

The original article was corrected. Author Muhammad Kundi should instead read: Muhammad Sohail.

To accelerate genetic gains in breeding, physiological trait (PT) characterization of candidate parents can help make more strategic crosses, increasing the probability of accumulating favorable alleles compared to crossing relatively uncharacterized lines. In this study, crosses were designed to complement “source” with “sink” traits, where at least one parent was selected for favorable expression of biomass and/or radiation use efficiency—source—and the other for sink-related traits like harvest-index, kernel weight and grains per spike. Female parents were selected from among genetic resources—including landraces and products of wide-crossing (i.e. synthetic wheat)—that had been evaluated in Mexico at high yield potential or under heat stress, while elite lines were used as males. Progeny of crosses were advanced to the F4 generation within Mexico, and F4-derived F5 and F6 generations were yield tested to populate four international nurseries, targeted to high yield environments (2nd and 3rd WYCYT) for yield potential, and heat stressed environments (2nd and 4th SATYN) for climate resilience, respectively. Each nursery was grown as multi-location yield trials. Genetic gains were achieved in both temperate and hot environments, with most new PT-derived lines expressing superior yield and biomass compared to local checks at almost all international sites. Furthermore, the tendency across all four nurseries indicated either the superiority of the best new PT lines compared with the CIMMYT elite checks, or the superiority of all new PT lines as a group compared with all checks, and in some cases, both. Results support—in a realistic breeding context—the hypothesis that yield and radiation use efficiency can be increased by improving source:sink balance, and validate the feasibility of incorporating exotic germplasm into mainstream breeding efforts to accelerate genetic gains for yield potential and climate resilience.

Leaf rust (Puccinia triticina Eriks.) is a fungal disease of wheat (Triticum spp.), which causes considerable yield loss. Adult plant resistance (APR) is one of the most sustainable approaches to control leaf rust. In this study, field-testing was carried out across ten different locations, followed by molecular screening, to detect the presence of APR genes, Lr34+, Lr46+, Lr67+ and Lr68 in Indian wheat germplasm. In field screening, 190 wheat accessions were selected from 6,319 accessions based on leaf tip necrosis (LTN), disease severity and the average coefficient of infection. Molecular screening revealed that 73% of the accessions possessed known APR genes either as single or as a combination of two or three genes. The occurrence of increased LTN intensity, decreased leaf rust severity and greater expression of APR genes were more in relatively cooler locations. In 52 lines, although the presence of the APR genes was not detected, it still displayed high levels of resistance. Furthermore, 49 accessions possessing either two or three APR genes were evaluated for stability across locations for grain yield. It emerged that eight accessions had wider adaptability. Resistance based on APR genes, in the background of high yielding cultivars, is expected to provide a high level of race non-specific resistance, which is durable.

High temperatures are a primary concern for wheat production in South Asia. A trial was conducted to evaluate the grain yield performance of high yielding, early maturing heat tolerant CIMMYT wheat lines, developed recently in Mexico for adaptation to high temperature stresses in South Asia. The trial, comprised of 28 entries and two checks, was grown in 13 locations across South Asia and two environments in Mexico. Each location was classified by mega environment (ME); ME1 being the temperate irrigated locations with terminal high temperature stress, and ME5 as warm, tropical, irrigated locations. Grain yield (GY), thousand kernel weight (TKW), days to heading (DH) and plant height (PH) were recorded at each location. Canopy temperature (CT) was also measured at some locations. Significant differences were observed between ME for DH, PH, GY, and TKW. The cooler ME1 locations had a mean DH of 83 days, compared to 68 days mean DH in ME5. The ME1 locations had higher mean GY of 5.26 t/ha and TKW of 41.8 g compared to 3.63 t/ha and 37.4 g, respectively, for ME5. Early heading entries (

A survey was carried out on leaf rust of wheat in kharif and rabi season during 2010–11 and 2011–12 in Karnataka. Survey in the districts Chikmagaluru and Chitradurga during kharif season of both the years revealed the absence of wheat cultivation in these areas. Survey (roving survey) during rabi, 2010–11 and 2011–12 revealed the difference in disease severity and incidence of leaf rust in different districts. Among seven districts; Belgaum, Bhagalkot, Bijapur, Dharwad, Gadag, Gulbarga and Yadgiri disease was observed only in three potential wheat growing districts viz., Belgaum, Dharwad and Gadag with severity ranges of 10MS-100S, 20MS-100S and 60S-80S, respectively during rabi, 2010–11 and 10MS-100S, 20MS-100S and 5S-100S respectively during rabi, 2011–12. The bread wheat variety DWR162 grown in large area (>50%) showed the highest disease severity and infection type in all surveyed districts. The pathotype 121R63-1 (77-5) was dominant and distributed in 35.71 per cent and 58.90 per cent during rabi 2010–11 and rabi 2011–12, respectively. Occurrence of a diverse population of pathotypes, some of which (12,104,162 group of pathotypes) do not occur in Nilgiri hills reveal that the surveyed areas form a different focus of infection.