No abstract

A network of 21 experiments was established across nine countries on four continents and spanning both hemispheres, to evaluate the relative performance of early generation perennial cereal material derived from wheat, rye, and barley and to inform future breeding strategies. The experimental lines were grown in replicated single rows, and first year production and phenology characteristics as well as yield and persistence for up to three years were monitored. The study showed that the existing experimental material is all relatively short-lived (≤3 years), with environments that are milder in summer and winter generally conferring greater longevity. No pedigree was superior across this diverse network of sites although better performing lines at the higher latitude sites were generally derived from Thinopyrum intermedium. By contrast, at lower latitudes the superior lines were generally derived from Th. ponticum and Th. elongatum parentage. The study observed a poor relationship between year 1 performance and productivity in later years, highlighting the need for perennial cereal material with greater longevity to underpin future experimental evaluation, and the importance for breeding programs to emphasize post-year 1 performance in their selections. Hybrid lines derived from the tetraploid durum wheat generally showed greater longevity than derivatives of hexaploid wheat, highlighting potential for greater use of Triticum turgidum in perennial wheat breeding. We advocate a model in future breeding initiatives that develops perennial cereal genotypes for specific target environments rather than a generic product for one global market. These products may include a diversity of cultivars derived from locally adapted annual and perennial parents. In this scenario the breeding program may have access to only a limited range of adapted perennial grass parents. In other situations, such as at very high latitude environments, perennial crops derived from barley or rye may have a better chance of success than those derived from wheat. In either case, development and selection of the perennial parent for adaptation to local environments would seem fundamental to success.

There are many socioeconomic and technological constraints that aVect the production of wheat and other staple cereals in South Asia. Wheat production is one of the economic mainstays in South Asia, but the yield gap between farmers' Welds and experimental yields is wide across the region. For the last 3 years, CIMMYT and the CAZS-NR have been collaborating with farmers, NARS, and other South Asian partners to promote improved wheat varieties and new resource conservation technologies (RCTs) in farmers' Welds. Participation fostered among farmers, scientists, extension specialists, NGOs and the private sector included variety selection (PVS), and evaluation of agronomic practices. Through PVS, several farmer-preferred technologies have been identiWed including wheat varieties for adverse conditions in eastern Uttar Pradesh (India) and for boron deWciency in parts of Nepal. There has been considerable improvement in the access of farmers to new varieties and technologies in the rural areas. Yield increases (15-70%) have been achieved by resource-poor farmers over the existing varieties through the adoption of new varieties and RCTs. The farmers have also made substantial cost savings and achieved higher yields through resource-conserving agronomic techniques such as zero till. Seed of the new farmerselected cultivars has been multiplied by groups of collaborating farmers and widely distributed.

High temperature stress adversely affects plant physiological processes; limiting plant growth and reducing grain yield. Heat stress is often encountered due to late sowing of wheat in winter. Fifty wheat genotypes were studied for days to maturity, thousand kernel weight, grain filling duration, grain filling rate, and SPAD reading in alpha lattice design at Agriculture and Forestry University at Rampur, Chitwan, Nepal with the objective to identify superior heat stress tolerant varieties after clustering them based on their response to heat stress. All the genotypes were clustered using reduction in thousand kernel weight, heat susceptibility index for thousand kernel weight, heat susceptibility index for grain filling duration, area under SPAD retreat curve, maturity duration under normal condition, maturity duration at late sown condition, grain filling rate under normal condition and grain filling rate at late sown condition as variables and dendogram was prepared. UPGMA revealed that these genotypes formed five distinct clusters. The resistant genotypes and susceptible genotypes formed different clusters. The member of cluster 3 was found to be tolerant to terminal heat stress where as members of cluster 2 were found most susceptible to terminal heat stress. From this study genotype BAJ #1/SUP152 was found most tolerant to terminal heat stress. The genotypes belonging to superior cluster could be considered very useful in developing heat tolerant variety and other breeding activities.

The diversity of agro-environmental conditions among wheatbased farming systems in the mountainous regions of Nepal may favor the development and production of multiple narrowly adapted varieties over a few broadly adapted varieties. Sixteen genotypes were tested using Participatory Varietal Selection (PVS) trials at farmers' fields in three districts in the Kathmandu Valley.Grain yield was the trait most preferred by farmers, followed by tillering, resistance to diseases, drought, and lodging. Farmer selection of optimal genotypes varied over time and location depending on agronomic and climatic pressures, indicating a preference by farmers for growing multiple, narrowly adapted varieties. Production potential of PVS genotypes averaged up to 142% greater than the most widely grown variety, RR21. With farmer participation in the selection process in different agroecological micro-niches of Nepal, both yield potential and yield stability of wheat should increase significantly, thereby providing farmers with the economic means to sustain the current smallscale agriculture suited to the mountainous terrain.

In wheat development programs, the evaluation and identification of superior genotypes  is the first and leading step in a crop improvement program. Coordinated Farmer’s Field Trial (CFFT) was conducted during the three successive wheat growing season of 2010/11, 2011/12 and 2012/13. In CFFT six different wheat genotypes were planted in different outreach sites of research stations of Nepal Agricultural Research Council (NARC) at varying geographical regions. CFFT was conducted according to standard recommended practices of wheat at farmers’ field with different sets of genotypes for Terai and hill. In CFFT for Terai Tar and Lower valley (TTL) under timely sown irrigated (TSI) condition wheat genotype NL 1073 produced the grain yield of 3695 kg/ha and under the timely sown rainfed (TSR) that was 2738 kg/ha in 2010/11. In 2011/12, wheat genotype NL 1073 had the highest recorded grain yield of 3691 kg/ha in mid western region which was followed by check variety Vijay in CFFT-TTL in 2011/12 in the same region. Similarly in 2012/13, check variety Vijay showed the highest grain yield of 3818 kg/ha and 3044 kg/ha followed by NL 1094 (2938 kg/ha and 3468 kg/ha) in TSR and TSI environments, respectively. In CFFT for Mid and High Hill (MHH) WK 1204 had the highest grain yield of 3967 kg/ha in TSI which was followed by NL 1008 with the yield of 3890 in 2010/11. In 2011/12 the highest mean grain yield was observed in WK 1204 (4242 kg/ha) followed by BL 3872 (3922 kg/ha). Similarly, in 2012/13 NL 1008 was the best genotypes on the basis of grain yield (3297 kg/ha) followed by NL 1055 (3131 kg/ha) under CFFT-MHH.

Since many of the quantitative plant characters of economic values are highly influenced by environmental condition, the progress in breeding in such a population is primarily conditioned by the magnitude, nature and inter-relations of genotypic and non-genotypic variations in plant characters. Therefore we estimated phenotypic, genotypic and environmental correlation coefficients and path coefficients among eight quantitative traits of bread wheat to make selection efforts more efficient. These traits were measured in 30 wheat genotypes, which were laid out in a randomized block design with three replications in Khumaltar, Kathmandu during 2003. The highest genotypic correlation (0.81) was between heading and maturity days. Tiller number was negatively correlated with grain number per spike (-0.78) at genetic level. Phenotypically, number of grains and grain weight per spike showed the largest coefficient (0.92) and maturity days exhibited negative association with plant height (-0.37). Environmental correlation coefficient was the highest between tillers number and grain yield (0.5) and heading days showed negative relationship with grain yield (-0.28). It indicates that number of tiller and grains per spike are the most important traits for yield. In most of the cases, genotypic correlations were higher than phenotypic correlations. Maturity days exerted the greatest influence (2.41) directly upon yield. Negative direct effect of heading days and positive effect of tiller number on yield was also considerable on magnitude. Indirect effect of heading days via maturity days was the highest followed by spike grain weight via maturity on grain yield. Results showed that grain filling period is an important factor and number of tillers and grains per spike should also be considered during selection for getting high yielding genotypes.

Wheat is a staple crop in Nepal and is the third major cereal crop grown across the country. To improve productivity and increase the number of farmers growing wheat, the Nepal Agricultural Research Council (NARC), since 1962, has been releasing new wheat varieties with higher productivity and disease resistance. Accurate identification of the varieties grown in farmer's fields is critical for assessing the adoption levels and the impact of new varieties. This understanding can change the landscape of the wheat market and the overall vulnerability of the crop to diseases and abiotic stresses. Current methods of identification that rely on farmer description and morphological traits have been associated with ambiguity. The objective of this study was to determine the varietal adoption of wheat in the seven wheat-growing provinces of Nepal using DNA fingerprinting technology. The study revealed that 'Gautam' and 'Vijay' are the most popular wheat varieties planted in the plain areas of Nepal. The area covered in these varieties during the 2018-2019 wheat season was 20.3 and 19.5% respectively. 'WK1204' was popular and mostly planted in the mountainous areas of Nepal during the October-May cropping season. The decommissioned varieties, including 'Pitic62', 'Kalyansona', 'Siddhartha', 'Vaskar', 'Vinayak', and 'NL 251' are still in use by 8% of wheat farmers across Nepal. Almost 38% of the varieties currently grown were released 20 yr ago. The varietal adoption was determined using molecular markers through fingerprinting, and its implications are discussed in this paper.