Direct selection for yield under drought has resulted in the release of a number of drought-tolerant rice varieties across Asia. In this study, we characterized physiological traits affected by that strategy in breeding trials across sites in Bangladesh, India, and Nepal. The drought breeding lines and drought-tolerant varieties showed consistently longer flag leaves and lower stomatal density than the drought-susceptible check, IR64. The influence of environmental parameters other than drought treatments on leaf traits was evidenced by the close grouping of treatments within a site. Flag leaf length and width appeared to be regulated by different environmental parameters. In separate trials in the Philippines, the same breeding lines studied in South Asia showed that canopy temperature under drought and harvest index across treatments were most correlated with grain yield. Both atmospheric and soil stress increased the relationship between leaf traits and yield. The stable expression of leaf traits among genotypes and the identification of the environmental conditions in which they contribute to yield, as well as the observation that some breeding lines showed longer time to flowering and higher canopy temperature than IR64, suggest that selection for additional physiological traits may result in further improvement of this breeding pool.

Aims Drought is the major constraint to rainfed rice productivity in South Asia, but few reports provide detailed characterization of the soil properties related to drought stress severity in the region. The aim of the study was to provide a compilation of drought breeding network sites and their respective levels of drought stress, and to relate soil parameters with yield reduction by drought. Methods This study characterized levels of drought stress and soil nutrient and physical properties at 18 geographically distributed research station sites Plant Soil (2017) 417:377-392 DOI 10.1007 Responsible Editor: Martin Weih. involved in rice varietal screening in Bangladesh, India, and Nepal, as well as at farmers' fields located near the research stations. Results Based on soil resistance to penetration profiles, a hardpan was surprisingly absent at about half of the sites characterized. Significant relationships of depth of compaction and yield reduction by drought indicated the effects of soil puddling on susceptibility to cracking, rather than water retention by hardpans, on plant water availability in this region. The main difference between research stations and nearby farmers' fields was in terms of soil compaction.Conclusions These results present an initiative for understanding the range of severities of reproductive-stage drought stress in drought-prone rainfed lowland ricegrowing areas in South Asia.

Wheat (Triticum aestivum L.) is one of the major cereal crops and staple food sources in Nepal. Wheat varieties being popular in mid hill regions are still in the early stages of adoption. Identification of appropriate date of seeding plays important role in enhancing the adoption rate ensuring the sustainable production. Therefore, three dates viz 15 th November, 1 st and 15 th December for seeding and twenty eight wheat genotypes were evaluated in a split plot design with two replications for two consecutive seasons in 2011/12 and 2012/13 at an altitude of 2200 masl of eastern Nepal. The results showed genetic differences and interaction effect of genotypes with the dates of sowing on grain yield, panicle length and effective tillers per square meter. The wheat sown on 1 st December showed the highest yield as compared to other sown dates. Similarly, WK1907, WK1911, WK1803, WK1915, WK1909, WK1714 and WK1803 produced highest yield among the tested genotypes with retaining maximum number of effective tillers and posed suitable maturity across all sowing date.

High temperature stress unfavorably affects plant growth and reduces grain yield (GY). This study was conducted with an aim to identify the terminal heat tolerance of one hundred and two wheat genotypes with three checks. They were sown under normal (non-stress) and late (stress) conditions at Regional Agricultural Research Station (RARS), Tarahara; RARS, Nepalgunj and National Wheat Research Program (NWRP), Bhairahawa, Nepal. The trial was sown in Augmented design during 2014/15 winter season as a Nepal heat tolerance wheat screening nursery (NHTWSN). Grain yield, maturity, stress susceptibility and tolerant indices were estimated to assess the heat tolerance of the genotypes. Combined analysis among the tested wheat lines (102 new entries + 3 checks) showed that KACHU//KIRITATI/WBLL1 ((Heat tolerance index (HTI) = 1.78) possessed the highest level of heat tolerance, followed by SLVS  /3/ CROC_1/ AE.SQUARROSA (224)// OPATA/5/ VEE/LIRA//BOW/3/BCN/4/KAUZ/6/ 2*KA/NAC//TRCH (HTI=1.57) while SUP152/VILLA JUAREZ F2009 (HTI=0.83) appeared to be the least heat tolerant. Correlation analysis showed that yield under stress environment had positive (r=0.083) and significant (p<0.05) association with that of non-stress environment. Grain yield (Kg/ha) under both environments had significant positive correlation with mean productivity (MP), geometric mean productivity (GMP) and HTI. Thirty seven wheat genotypes possessing heat tolerance will be considered in further heat tolerance trial and can also be used directly in varietal development and in the crossing program to breed more heat tolerant genotypes.

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The coordinated and regional varietal trial of normal season irrigated rice was carried out at Regional Agricultural Research Station (RARS), Tarahara, Nepal in 2014 & 2015 Out of the tested genotypes, NR 2157-166-1-3-5-1, Cieharang sub-1 and NR 2157-166-2-1-1-1 identified as promising with potential grain yield of 4313, 4290 and 4239 kg/ha respectively in over year analysis (2014-15) of coordinated varietal trial (CVT). These genotypes recorded 25 to 27 percent higher grain yield than national rice productivity and 4 to 6 percent more than check variety, Sabitri. The differences in grain yield among the tested genotypes and between the years were found significant, but interaction of genotypes to year was found non-significant. Similarly, KARAJAT-3 recorded the highest grain yield (4897 kg/ha) followed by NR 1190-24-4-2-2-2-3-2 (4861 kg/ha) in over year analysis (2014-15) of regional varietal trial (RVT), similarly and identified as promising genotypes. These promising genotypes recorded 43 and 8 percent higher grain yield than national rice yield and to the check variety, Sabitri, respectively in over year analysis. The differences in grain yield among genotypes and year were found significant.

The seed materials were received from National Wheat Research Program, Bhairahawa and field experiment was conducted at Regional Agricultural Research Station Tarahara during 2012 and 2013 in wheat growing season. The topography of the experimental site was 130 masl with sandy loam soil. The trial included 24 wheat genotypes laid out in alpha lattice design in eight sub blocks within two main blocks. The eastern region of Nepal has been facing the problem of sterility caused by different stresses during reproductive growth stage. So we need to develop the early maturing variety with high yielding potential that could escape the reproductive damage from rainfall, hot westerly wind and leaf rust epidemic. In this study, we identified BL3594, NL1026, NL297, BL3978 and NL1140 as early maturing wheat genotypes with 102, 102, 101, 97 and 102 days of maturity, respectively. The genotypes varied significantly for heading days, maturity days, plant height, spikes per meter square, grain per spikes and grain yield ton per hector. The most stable yield producing genotypes were BL3264, BL3535, BL3623, NL1135 and BL3978. The variety BL3978 had maturity duration of 97 days, even earlier than check variety NL297. The genotypes NL1093 and NL1094 had highest grain per spikes although had negative correlation coefficient with panicle length consequently led to the lower yield. The new genotypes like BL3978, BL3594 and NL1140 should be promote as appropriate varieties for terai region of Nepal.

ABSRACTA field experiment was conducted for two years using six genotypes of wheat (Triticum aestivum L.) for response to different levels of nitrogen (N) use. The experiment was laid out in split plot design with four levels (0, 50, 100 and 150 kg N ha -1 ) as main plots and six wheat genotypes (BL 3623, BL 3629, BL 3872, NL 1008, NL 1055 and Vijay, a check variety) as sub-plots. Grain yield and other yield components increased linearly in response to N concentrations in both seasons. Only two parameters: days to heading (DOH) and days to maturity (DTM) varied significantly (p ≤ 0.05) among wheat genotypes in both the years. None of the parameters showed interaction effects in both seasons. Vijay showed highest grain yield of 3.12 t ha -1 in 2013 with the application of 100 kg N ha