排序方式： 共有9条查询结果，搜索用时 294 毫秒
1
1.
Meghnath Pokharel Anuj Chiluwal Michael Stamm Doohong Min Davina Rhodes S.V. Krishna Jagadish 《Journal of Agronomy and Crop Science》2020,206(5):579-596
Winter canola (Brassica napus L.) is highly sensitive to increasing temperatures during the reproductive and pod-filling stages. Although the impact of high day-time temperature stress on yield and quality has been documented in canola, similar information under high night-time temperature (HNT) stress is not available. Using six hybrids and four open-pollinated cultivars, we observed a marked shift in peak flowering towards earlier, cooler hours of the morning under HNT. Averaged across two independent experiments, the photochemical efficiency of photosystem II was significantly decreased (3%), with a significant increase in thylakoid membrane damage (13%) in the leaves of susceptible cultivars under HNT stress. Similarly, the susceptible cultivars also recorded significant reduction in biomass (34%), pod number (22%), pod weight (37%) and total seed weight (40%) per plant while the same set of agronomic traits were not affected among the tolerant cultivars. Quantitative impact of heat stress was confirmed with increased sensitivity to HNT exposure from gametogenesis until maturity resulting in a significantly higher yield loss compared to stress exposure from post-flowering till maturity. HNT significantly decreased oil concentration, but increased protein concentration and saturated fatty acid levels in seeds of the susceptible cultivars. However, HNT had no impact on the unsaturated fatty acids in both hybrids and the open-pollinated cultivars. Breeding targets based on fatty acid composition for enhancing canola seed quality may not be easily amenable due to the inconsistency documented with the compositional changes under heat stress. In summary, our findings conclude that canola hybrids are better suited to regions experiencing heat stress, compared to open-pollinated cultivars, indicating the possibility of a complete shift to hybrid canola cultivation under predicted hotter climates in the future. 相似文献
2.
Processes to develop criteria and indicators (C and I) for sustainableforest management are often expert driven. Although the long-termobjective of the Nepalese forest policy is sustainable forestmanagement, no national level C and I specifically for thishave been developed. However, the Ministry of Forests and SoilConservation awards an annual prize to successful communityforest user groups (CFUGs) based on evaluation according to10 criteria. This study explored local C and I for successfulforest management in Nepal through six meetings with CFUG members.A total of 14 local criteria and 52 indicators for awardinga prize to successful CFUGs were identified, and comparisonwith official C and I was undertaken. Most conspicuously, localC and I focus more on environmental and governance-related aspectsthan the official list, and the official list leaves much tothe discretion of the evaluator. The study concludes that developmentof a national level C and I for sustainable forest managementcould benefit from involvement of local forest users. 相似文献
3.
Prem?Pokharel Jin-Hyeob?Kwak Scott?X.?ChangEmail author 《Biology and Fertility of Soils》2017,53(6):701-713
We evaluated the impact of exponential fertilization in nursery and weed removal in the field on growth and nitrogen (N) retranslocation and uptake from the soil of jack pine (Pinus banksiana Lamb.) seedlings planted on an oil sands reclaimed soil. Exponential fertilization is a method of supplying nutrients at an exponential rate to achieve constant internal nutrient concentrations in seedlings without changing their size during their growth in the nursery. The N retranslocation in seedlings was traced using 15N isotope labeling. Exponential fertilization increased nutrient reserve in the seedling in nursery production, and increased height (P = 0.003), root collar diameter (P < 0.001), total biomass (P < 0.001), and N content (P < 0.001) of seedlings at the end of first growing season in the field growth. Conventionally fertilized seedlings allocated a greater percent of biomass to roots than to current-year needles. The 15N isotope analysis showed that 59 to 82% of total N demand of new growth was met by retranslocation from old tissues. Exponential fertilization increased N retranslocation by 147% (P < 0.001) and N uptake from the soil by 175% (P = 0.012). Weed removal marginally increased (P = 0.077) N uptake from the soil but decreased (P = 0.046) N retranslocation with no net effect on total N content in new tissues. We conclude that exponential fertilization improves the early growth of jack pine and can help improve revegetation in reclaiming disturbed oil sands sites. 相似文献
4.
5.
6.
J Kellosalo T Kajander K Kogan K Pokharel A Goldman 《Science (New York, N.Y.)》2012,337(6093):473-476
Membrane-integral pyrophosphatases (M-PPases) are crucial for the survival of plants, bacteria, and protozoan parasites. They couple pyrophosphate hydrolysis or synthesis to Na(+) or H(+) pumping. The 2.6-angstrom structure of Thermotoga maritima M-PPase in the resting state reveals a previously unknown solution for ion pumping. The hydrolytic center, 20 angstroms above the membrane, is coupled to the gate formed by the conserved Asp(243), Glu(246), and Lys(707) by an unusual "coupling funnel" of six α helices. Comparison with our 4.0-angstrom resolution structure of the product complex suggests that helix 12 slides down upon substrate binding to open the gate by a simple binding-change mechanism. Below the gate, four helices form the exit channel. Superimposing helices 3 to 6, 9 to 12, and 13 to 16 suggests that M-PPases arose through gene triplication. 相似文献
7.
Evaluation of performance, carcass characteristics, and sensory attributes of beef from finishing steers fed field peas 总被引：1，自引：0，他引：1
Jenkins KH Vasconcelos JT Hinkle JB Furman SA de Mello AS Senaratne LS Pokharel S Calkins CR 《Journal of animal science》2011,89(4):1167-1172
Whole field peas were fed at 0, 10, 20, and 30% of DM to 139 yearling steers (British cross; 409 ± 31 kg of initial BW) for a 119-d finishing period. Carcass data and Choice grade strip loins (n = 98) were collected from a commercial abattoir in Lexington, Nebraska. Consumer sensory and Warner-Bratzler shear force analyses were performed on 2.5-cm strip steaks. No differences (P ≥ 0.17) were observed in final BW, ADG, DMI, and G:F of steers. Likewise, no differences (P ≥ 0.23) were observed for HCW, LM area, fat thickness at the 12th rib, yield grade, and marbling scores. However, KPH responded quadratically to increasing dietary amount of field peas (P = 0.02). Regarding the sensorial analysis, feeding peas linearly increased subjective tenderness (P < 0.01) and led to a quadratic response of overall like ratings (P = 0.01) and flavor like ratings (P = 0.12). Feeding peas did not alter (P ≥ 0.64) juiciness, but decreased shear force values linearly when quantities were increased (P = 0.02). These data suggest that feeding peas does not affect steer performance or carcass characteristics differently from dry-rolled corn, but does improve objective and subjective tenderness, overall desirability, and flavor of beef. Field peas could be fed to cattle and give positive attributes to the quality of the meat up to 30% inclusion in the diet. 相似文献
8.
The utility of site index as a predictor variable in models for complex, mixed species stands is limited because the site index concept is not well suited for these stand types. Additionally, there is no standard protocol of estimating site index for uneven-aged mixed species stands, which is evident in permanent sample plot (PSP) and co-operative (COOP) data sets available from the Province of Ontario, Canada. Under such circumstances, an alternative to site index in a basal area increment model was explored, using a combination of climate and Forest Ecosystem Classification (FEC) variables from the Ontario boreal region. Among the four candidate climate variables chosen, mean annual temperature (MAT) explained the most variability in basal area increment for the four selected tree species – trembling aspen (Populus tremuloides Michx.), balsam fir (Abies balsamea (L.) Mill.), jack pine (Pinus banksiana Lamb.), and black spruce (Picea mariana (Mill.) B.S.P.). Our results indicated that a combination of the climate variable, MAT, and FEC explained a substantially higher proportion of variation in the basal area increment than site index alone. Thus, climate and FEC variables are superior substitutes in the basal area increment model even when error-free site index values are possible to obtain. 相似文献
9.
There is a variety of forest management institutions ranging from state management to community and private management. This article attempts to identify the conditions under which one institution outperforms the others in the efficiency of forest management based on a review of the literature, empirical evidence on the dominant forest management institutions, and theoretical arguments. In conclusion, we argue that the community management system performs best for nontimber forests, whereas a mixed management system, in which forest protection is carried out communally and tree management is carried out individually, is likely to work best for timber forests. 相似文献
1