Biotic and biotic constraints are yield limiting factors in maize producing regions. Among these gray leaf spot is a yield limiting foliar disease of maize in high land regions of Asia. This review is done from related different national and international journals, thesis, books, research papers etc. The objectives of this review are to become familiar with genetics and inheritance, epidemiology, symptoms and disease management strategies etc. High relative humidity, temperature, minimum tillage and maize monoculture are important factors responsible for disease development. The sibling species of Cercospora zeae-maydis (Tehon and Daniels, 1925) Group I and Group II and Cercospora sorghai var. maydis (Chupp, 1954) are associated with this disease. Pathogens colonize in maize debris. Conidia are the source of inoculums for disease spread. Severe blighting of leaves reduces sugars, stalk lodging and causes premature death of plants resulting in yield losses of up to 100%. Disease management through cultural practices is provisional. The use of fungicides for emergencies is effective however; their prohibitive cost and detrimental effects on the environment are negative consequences. The inheritance of tolerance is quantitative with small additive effects. The introgression of resistant genes among the crosses of resistant germplasm enhances the resistance. The crosses of resistant and susceptible germplasm possess greater stability than the crosses of susceptible and resistant germplasm. The development of gray leaf spot tolerant populations through tolerance breeding principle is an economical and sustainable approach to manage the disease.Journal of Maize Research and Development (2015) 1(1):71-85DOI: http://dx.doi.org/10.5281/zenodo.34286

Most parts of the Asian tropics are hotspots of climate change effects and associated weather variabilities. One of the major challenges with climate change is the uncertainty and inter-annual variability in weather conditions as crops are frequently exposed to different weather extremes within the same season. Therefore, agricultural research must strive to develop new crop varieties with inbuilt resilience towards variable weather conditions rather than merely tolerance to individual stresses in a specific situation and/or at a specific crop stage. C4 crops are known for their wider adaptation to range of climatic conditions. However, recent climatic trends and associated variabilities seem to be challenging the threshold limit of wider adaptability of even C4 crops like maize. In collaboration with national programs and private sector partners in the region, CIMMYT-Asia maize program initiated research for development (R4D) projects largely focusing on saving achievable yields across range of variable environments by incorporating reasonable levels of tolerance/resistance to major abiotic and biotic stresses without compromising on grain yields under optimal growing conditions. By integrating novel breeding tools like - genomics, double haploid (DH) technology, precision phenotyping and reducing genotype × environment interaction effects, a new generation of maize germplasm with multiple stress tolerance that can grow well across variable weather conditions were developed. The new maize germplasm were targeted for stress-prone environments where maize is invariability exposed to a range of sub-optimal growing conditions, such as drought, heat, waterlogging and various virulent diseases. The overarching goal of the stress-resilient maize program has been to achieve yield potential with a downside risk reduction.

Midhills, foot hills and river basin areas of are generally under spring maize cultivation. These areas along with the areas from Terai and Inner Terai where spring and early summer maize are grown are the most affected from heat stress. Identification and selection of suitable varieties and traits for high temperature tolerance is vital to produce heat resilient genotypes.With a view to identify high yielding heat stress resilient maize hybrids, genotypes received from International Maize and Wheat Improvement Centre (CIMMYT) were evaluated in alpha lattice design with two to three replications at Rampur, Nepalgunj and Surkhet in 2013/014, 2014/015 and 2015/016. Total 57 trials consisting of 7764 maize hyrbids were evaluated under heat stress conditions. At Nepalgunj and Surkhet, trials were planted in March/April. Out of the tested genotypes, 24 hybrids were found promising based on grain yield, plant and ear height. These 24 hybrids along with four National Maize Research Program (NMRP) developed and two multi-national companies' hybrids as checks were tested in multilocation trials at Dumarwana, Nijgadh, Nawalparasi and Rampur in 2014/015. Out of these 24 hybrids, eight were selected and tested during 2015/016 in Dumarwana, Nijgadh, Nawalparasi, Anandapur and Rampur. Based on results combined over years and locations CAH-151 (8629 kg ha -1 ) and CAH-153 (8955 kg ha -1 ) were registered for general cultivation as Rampur Hybrid-8 and Rampur Hybrid-10, respectively. Other promising hybrids were CAH-1511 (8800 kg ha -1 ) followed by CAH-1515 (8678 kg ha -1 ), RML-95/RML-96 (8486 kg ha -1 ), CAH-1513 (8258 kg ha -1 ) and RML-86/RML-96 (7544 kg ha -1 ), respectively. Stability analysis revealed that CAH-151, CAH-153, CAH-1515, CAH-1511 and RML-95/RML-96 are stable hybrids having good performance.

Development of a crop variety with high grain yield and stability in test locations is an important part of crop breeding program. Thirteen foxtail millet genotypes were evaluated in randomized complete block design with three replications in Jumla and Dolakha, Nepal from April to August in three consecutive years 2017, 2018, and 2019. The objective of this study was to analyze grain yield stability and adaptability of foxtail millet genotypes applying genotype main effect plus genotype by environment interaction (GGE) biplot analysis. The results showed that grain yields were significantly (P<0.05) affected by the environment (E), genotype (G), and their interaction (G×E). The genotype HUMLA-163 had regression coefficient equal to unity (b=1.01), thus this genotype had average adaptation to all environments whereas HUMLA-213 (b=1.18) and HUMLA-252 (b=1.19) had regression coefficients greater than unity, thus these genotypes were more adapted to favorable environments. GGE biplot showed that HUMLA-163 was more stable and adaptive genotype. Thus, genotype HUMLA-163 is recommended for release as a variety to improve foxtail millet production in hilly region of Nepal.

Hybrid plays an important role in production and productivity increment of maize in potential pockets of middle hills. With an objective of identifying potential hybrids for middle hill environments, coordinated varietal trials on maize hybrids were conducted using randomized complete block design with three replications in various hill stations during summer of 2014/15 and 2015/16. During 2014/015, significant differences were recorded among the genotypes at Khumaltar and Pakhribas, where non-significant at Kabre for grain yield. Combined results of hill stations for grain yield revealed highly significant differences for genotypes, environments and, genotype by environment interactions indicating existence of variability among the tested genotypes at each site except at Kabre, and site specific nature of the tested hybrids was recorded. JM-8 produced the highest grain yield of 8356 kg ha-1 followed by RL-153/RL-105 (8006 kg ha-1), RML-95/RL-105 (7940 kg ha-1) and Khumal Hybrid-2 (7788 kg ha-1), respectively. In 2015/16, among the experimented hybrids highly significant grain yield differences were observed at Pakhribas and Khumaltar, and significant at Dailekh. Combined results over locations showed that RML-95/RL-197 (7365 kg ha-1) outyielded others and followed by RML-95/RL-105 (7010 kg ha-1), RML-151/RL-111 (6717 kg ha-1) and RML-87/RL-105 (6580 kg ha-1). Hybrids having higher grain yield in coordinated varietal trials will be promoted to Coordinated Farmers' Field Trial on Hybrid and these hybrids might be the potential hybrids in future for potential pockets of middle hills of Nepal.