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Ghimire K.H.,University of the Philippines at Los Baños | Ghimire K.H.,Nepal Agricultural Research Council | Quiatchon L.A.,University of the Philippines at Los Baños | Quiatchon L.A.,International Rice Research Institute | And 7 more authors.
Field Crops Research | Year: 2012

The identification and introgression of QTLs for grain yield under drought is a preferred breeding strategy to improve the drought tolerance of popular elite rice varieties. Swarna and IR64 are two high-yielding rice varieties widely grown in rainfed areas of South and Southeast Asia but they are highly sensitive to drought. Dhagaddeshi, a traditional drought-tolerant donor, was crossed with Swarna and IR64 to develop two recombinant inbred line populations. The two populations were phenotyped for grain yield under reproductive-stage drought stress and non-stress during DS2010 and DS2011. Bulk segregant analysis was followed to identify the loci linked to grain yield under drought. A major-effect QTL, qDTY 1.1, for grain yield under drought was identified on chromosome 1 between the marker intervals RM431 and RM12091 in both populations. The Dhagaddeshi allele at qDTY 1.1 contributed to increased yield under drought and explained 32.0% and 9.3% of the phenotypic variance and 24.9% and 8.6% additive effect of the trial mean yield in Dhagaddeshi×Swarna and Dhagaddeshi×IR64 populations, respectively. A consistent effect of qDTY 1.1 has also been reported earlier. The presence of qDTY 1.1 in several traditional drought-tolerant donors and its consistent effect across the genetic backgrounds makes it a suitable QTL for use in marker-assisted breeding to improve the grain yield of drought-susceptible rice varieties. © 2012 Elsevier B.V.


Jensen B.D.,Copenhagen University | Vicente J.G.,University of Warwick | Roberts S.J.,Nepal Agricultural Research Council | Manandhar H.K.,Plant Health Solutions
Plant Disease | Year: 2010

Black rot caused by Xanthomonas campestris pv. campestris was found in 28 sampled cabbage fields in five major cabbage-growing districts in Nepal in 2001 and in four cauliflower fields in two districts and a leaf mustard seed bed in 2003. Pathogenic X. campestris pv. campestris strains were obtained from 39 cabbage plants, 4 cauliflower plants, and 1 leaf mustard plant with typical lesions. Repetitive DNA polymerase chain reaction-based fingerprinting (rep-PCR) using repetitive extragenic palindromic, enterobacterial repetitive intergenic consensus, and BOX primers was used to assess the genetic diversity. Strains were also race typed using a differential series of Brassica spp. Cabbage strains belonged to five races (races 1, 4, 5, 6, and 7), with races 4, 1, and 6 the most common. All cauliflower strains were race 4 and the leaf mustard strain was race 6. A dendrogram derived from the combined rep-PCR profiles showed that the Nepalese X. campestris pv. campestris strains clustered separately from other Xanthomonas spp. and pathovars. Race 1 strains clustered together and strains of races 4, 5, and 6 were each split into at least two clusters. The presence of different races and the genetic variability of the pathogen should be considered when resistant cultivars are bred and introduced into regions in Nepal to control black rot of brassicas. © 2010 The American Phytopathological Society.


Gaihre Y.K.,International Rice Research Institute | Gaihre Y.K.,University of the Philippines at Los Baños | Gaihre Y.K.,Nepal Agricultural Research Council | Wassmann R.,International Rice Research Institute | And 2 more authors.
Plant and Soil | Year: 2013

Aims: Two pot experiments in a "walk-in" growth chamber with controlled day and night temperatures were conducted to investigate the influence of elevated temperatures along with rice straw incorporation on methane (CH4) and nitrous oxide (N2O) emissions as well as rice yield. Methods: Three temperature regimes-29/25, 32/25, and 35/30 °C (Exp. I) and 29/22, 32/25, and 35/28 °C (Exp. II), representing daily maxima/minima were used in the study. Two amounts of rice straw (0 and 6 t ha-1) were applied with four replications in each temperature regime. CH4 and N2O emissions as well as soil redox potential (Eh) were monitored weekly throughout the rice-growing period. Results: Elevated temperatures increased CH4 emission rates, with a more pronounced effect from flowering to maturity. The increase in emissions was further enhanced by incorporation of rice straw. A decrease in soil Eh to <-100 mV and CH4 emissions was observed early in rice straw-incorporated pots while the soil without straw did not reach negative Eh levels (Exp. I) or showed a delayed decrease (Exp. II). Moreover, soil with high organic C (Exp. II) had higher CH4 emissions. In contrast to CH4 emissions, N2O emissions were negligible during the rice-growing season. The global warming potential (GWP) was highest at high temperature with rice straw incorporation compared with low temperature without rice straw. On the other hand, the high temperature significantly increased spikelet sterility and reduced grain yield (p < 0.05). Conclusions: Elevated temperature increased GWP while decreased rice yield. This suggests that global warming may result in a double negative effect: higher emissions and lower yields. © 2013 Springer Science+Business Media Dordrecht.


Gaihre Y.K.,International Rice Research Institute | Gaihre Y.K.,University of the Philippines at Los Baños | Gaihre Y.K.,Nepal Agricultural Research Council | Wassmann R.,International Rice Research Institute | And 4 more authors.
Agriculture, Ecosystems and Environment | Year: 2014

Rice fields are considered as one of the major sources of methane (CH4), and they also emit nitrous oxide (N2O). A field experiment was conducted at the International Rice Research Institute, Philippines, in 2010-2011 using a temperature free-air controlled enhancement (T-FACE) system. Our objectives were to assess (i) the suitability of the T-FACE system for flooded rice fields and (ii) seasonal variations in greenhouse gas emissions with and without experimental warming.This observation period included one wet season (WS), one dry season (DS), and a fallow season. The experimental warming, i.e., T-FACE system, was maintained by using six infrared heaters deployed in a hexagonal pattern over each plot (7.1m2). Set-point canopy temperatures of the warming treatment were 1.5 and 3.0°C higher than the reference plots during daytime and nighttime, respectively. Two warming treatments (i.e., heated and reference) were arranged in a randomized complete block design with three replications. Infrared warming increased rice canopy temperature by 1.1 and 2.6°C (0.4°C below the targeted set-point) during daytime and nighttime, respectively. On the other hand, only a marginal (0.4-0.5°C) increase was observed for both water and soil temperatures, likely because flood irrigation water flowed across the field. The warming (elevated canopy temperature) had no significant effects on CH4 or N2O emissions during the dry, wet, and fallow seasons. However, diel and seasonal variations in CH4 emissions were observed during the rice-growing and fallow periods. CH4 emissions were higher during the early afternoons, which was positively correlated with both soil and air temperatures. Similarly, CH4 emission rates increased with rice growth stage up to the reproductive stage. Moreover, cumulative CH4 emissions were 1.5 times higher in the 2011 DS than in the 2010 WS (50 and 34gCH4m-2, respectively). The 2-month fallow season (late May-early July 2011) under continuous flooding emitted 51gCH4m-2, which is similar to that in the 2011 DS. On the other hand, N2O emissions were not detected throughout the growing season, but an emission peak was observed after final drainage at maturity during the 2011 DS. Both rice-growing and fallow seasons were the major sources of CH4 emissions as long as the field was continuously flooded, while N2O was not detectable in continuously flooded soil. Infrared warming did not affect rice yields or yield components, probably because the general growing temperatures were near optimum, and the warming treatment was not sufficiently large to cause a significant effect. © 2013 Elsevier B.V.


He J.,China Agricultural University | Li H.,China Agricultural University | Rasaily R.G.,China Agricultural University | Rasaily R.G.,Nepal Agricultural Research Council | And 5 more authors.
Soil and Tillage Research | Year: 2011

Soil deterioration and the accompanying decline in crop yields are the main factors limiting the further development of agriculture in North China Plain. The long-term effects of no tillage (NT) and conventional tillage (CT) on soil properties and crop yields were investigated in annual double cropping system of winter wheat-summer maize in the Gaocheng in Hebei, North China Plain over a 11-year period (1998-2009). Long-term NT significantly (P< 0.05) increased soil organic matter, available N and P in the top 10. cm by 16.1%, 31.0% and 29.6% as compared to CT treatment. Mean percentage of macro-aggregates (>0.25. mm, +8.1%) and macroporosity (>60. μm, +43.3%) was also enhanced statistically (P< 0.05) in the 0-30. cm soil layer. Winter wheat and summer maize yields tended to be 3.5% and 1.4% higher under NT than under CT, particularly in the dry years, suggesting that the change in soil physical properties, soil fertility and moisture has provided a better environment for crop development. These improvements in soil properties and yields are of considerable importance for the degraded soils in semiarid North China Plain, as well as for food security, sustainable agriculture and carbon storage in the annual double cropping areas of China. © 2011 Elsevier B.V.


Upadhyay K.P.,Nepal Agricultural Research Council
Acta Horticulturae | Year: 2010

Cucumber production in winter in Nepal fetches off-season market. To select appropriate cultivar, local and exotic cultivars were evaluated in three-meter high plastic house (plastic quality 500 gauge) at Regional Agricultural Research Station (RARS), Lumle, Nepal (1,675 m.a.s.l.) from late winter to summer season in 2003, 2004 and 2005. Replicated experiment was conducted with seven cultivars in first year, selected six in second year and five in third year under a randomized complete block (RCB) design. Seedlings raised in polypots before one month of transplanting were transplanted at 1.5 m (row to row) × 1.5 m (plant to plant). Fertilizers were applied with 20 tons FYM and 60:30:25 N:P2O5:K2O kg/ha. Observations were recorded on yield related parameters. The overall results revealed that the 'Mahyco Green Long', an Indian cultivar was superior in all the years. The popular local cultivar 'Bhaktapur Local' was found at par with 'Mahyco Green Long'. This result gives new information on cultivars suitable for winter cucumber production which are superior to existing recommended cultivar 'Kusule' and other cultivars.


Adhikari D.,The University of Shimane | Adhikari D.,Nepal Agricultural Research Council | Itoh K.,The University of Shimane | Suyama K.,The University of Shimane
Plant and Soil | Year: 2013

Background and Aims: This study was conducted to reveal the genetic diversity of common bean (Phaseolus vulgaris L.) nodulating rhizobia in various agroecological regions in Nepal. Method: A total of 63 strains were isolated from common bean grown in the soils collected from seven bean fields in Nepal and characterized based on the partial sequences of 16S-23S internal transcribed spacer (ITS) regions, 16S rDNA, nodC, and nifH. Symbiotic properties of some representative strains with host plants were examined to elucidate their characteristics in relation to genotype and their origin. Results: The isolated strains belonged to Rhizobium leguminosarum, Rhizobium etli, Rhizobium phaseoli, and one unknown Rhizobium lineage, all belonging to a common symbiovar (sv.) phaseoli. Nine ITS genotypes were detected mainly corresponding to a single site, including a dominant group at three sites harboring highly diverse multiple ITS sequences. Three symbiotic genotypes corresponded to a geographical region, not to the ribosomal DNA group, suggesting horizontal transfer of symbiotic genes separately in each region. Great differences in nitrogenase activity and nodule forming ability among the strains irrespective of their species and origin were observed. Conclusions: Nepalese Himalaya harbor phylogenetically highly diverse and site-specific strains of common bean rhizobia, some of which could have high potential of symbiotic nitrogen fixation. © 2012 Springer Science+Business Media Dordrecht.


Adhikari D.,The University of Shimane | Adhikari D.,Nepal Agricultural Research Council | Kaneto M.,The University of Shimane | Itoh K.,The University of Shimane | And 3 more authors.
Plant and Soil | Year: 2012

Backgroud and aims: This study was conducted to reveal the genetic diversity of soybean-nodulating rhizobia in Nepal in relation to climate and soil properties. Method: A total of 102 bradyrhizobial strains were isolated from the root nodules of soybeans cultivated in 12 locations in Nepal varying in climate and soil properties, and their genetic diversity was examined based on 16S rDNA, ITS regions of 16S-23S rDNA, nodC and nifH. In vitro growth properties of some representative strains were examined to elucidate their characteristic distribution in Nepal. Results: Four species of the genus Bradyrhizobium were isolated, and B. japonicum dominated at temperate locations, while in subtropical locations, B. elkanii, B. yuanmingense, and B. liaoningense dominated at acidic, moderately acidic, and slightly alkaline soils, respectively. The relative nodule occupancies could not be fully explained by their in vitro growth properties. Similar nodC and nifH genes among the strains suggested co-evolution of these genes also in Nepal, probably through horizontal gene transfer. Conclusions: The influence of climate and soil pH on diversity at the sub-species level was revealed. It is concluded that the highly diverse climate and soils in Nepal might be conducive for the existence of diverse soybean rhizobial strains. © 2012 Springer Science+Business Media B.V.


Suzuki Y.,The University of Shimane | Adhikari D.,The University of Shimane | Adhikari D.,Nepal Agricultural Research Council | Itoh K.,The University of Shimane | Suyama K.,The University of Shimane
Plant and Soil | Year: 2014

Background and aims: Bradyrhizobium japonicum and Bradyrhizobium elkanii dominated soybean nodules in temperate and subtropical regions in Nepal, respectively, in our previous study. The aims of this study were to reveal the effects of temperature on the nodulation dominancy of B. japonicum and B. elkanii and to clarify the relationship between the effects of temperature and the climate-dependent distribution of Bradyrhizobium species. Methods: A laboratory competition experiment was conducted between B. japonicum and B. elkanii strains isolated from the same temperate location in Nepal. A mixture of each strain was inoculated into sterilized vermiculite with or without soybean seeds, and inoculated samples were incubated at 33/27 (day/night) and 23/17 °C. Relative populations in the non-rhizosphere, rhizosphere, and nodules were determined by competitive PCR using specific primers for each strain at 0, 1, 2, and 4 weeks after inoculation. Results: Both separately inoculated B. japonicum and B. elkanii strains formed nodules at both temperatures. Under competitive conditions, B. japonicum strains dominated at low temperature; however, at high temperature, both strains achieved co-nodulation in 1 week, with B. elkanii dominating after 2 weeks. The relative populations of both strains were similar in the non-rhizosphere and rhizosphere at low temperature, but B. elkanii strains dominated in these regions at high temperature. Conclusions: The domination of B. japonicum strains in nodules at the low temperature appeared to be due to preferential infection, while the domination of B. elkanii strains at high temperature appeared to be due to the higher population of B. elkanii in the non-rhizosphere and rhizosphere, in addition to its domination in nodules after co-nodulation. The effects of temperature on the competition between B. japonicum and B. elkanii strains were remarkable and corresponded with the distribution of bradyrhizobial species in Nepal. © 2013 Springer Science+Business Media Dordrecht.


PubMed | Nepal Agricultural Research Council and Kyoto University
Type: | Journal: Animal science journal = Nihon chikusan Gakkaiho | Year: 2016

Biochemical values and mineral concentrations in blood plasma were investigated to evaluate the statuses of health and mineral nutrition among yaks in Mustang District, Nepal. In total, 118 plasma samples of female yaks collected in April and September/October of 2013-2015 were offered. Seventy-four percent of yaks showed lower plasma total-cholesterol concentrations than the lowest limit of reference range (100mg/dL) and the values in spring (83.41mg/dL) were lower (P<0.05) than those in autumn (95.05mg/dL). All the yaks had lower plasma albumin concentrations than the lowest limit of reference range (3.0g/dL) and 66% of yaks showed lower plasma inorganic phosphorus concentrations than the critical level of phosphorus deficiency (4.5mg/dL). Thirty-five percent of yaks showed lower plasma calcium concentrations than the lowest limit of normal range (8mg/dL) and the concentrations were lower in spring than in autumn (P<0.01). Seventy-five percent of yaks presented lower copper concentrations than the critical level (0.65mg/L) and the concentrations were lower in spring than in autumn (P<0.01). Since the low plasma total-cholesterol might have indicated shortage of dry matter and energy intake, attention should be paid to the nutritional statuses of energy, phosphorus, calcium and copper in winter and early spring.

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