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1.
Evaluation of 'quick and dirty' DNA extraction methods for marker-assisted selection in rice (Oryza sativa L.) 总被引:2,自引:0,他引:2
Six simple methods for extracting DNA from rice seedlings were evaluated for marker‐assisted selection (MAS). The assessment of each method was based on PCR amplification of SSR markers, DNA yield and purity, time and cost. Based on these criteria, two methods were selected as being superior to other methods. The best two methods included the standard method developed at the International Rice Research Institute (IRRI), which utilizes a sodium dodecyl sulfate extraction buffer followed by chloroform/isoamyl alcohol extraction and a previously published method using sodium hydroxide and Tris. These two methods produced nearly identical PCR amplification results. The sodium hydroxide method is considerably simpler, quicker and cheaper than the standard IRRI method, and may be particularly useful for many applications of MAS or high‐resolution mapping. This method was also adapted into an effective high throughput method utilizing 96‐well plates emphasizing its versatility. 相似文献
2.
On-farm varietal diversity is now highest in marginal agricultural environments because, unlike the case in more favourable
areas, modern varieties have not been a sufficiently attractive option for farmers to replace their landraces. However, the
continued survival of landraces on farm is dependent on the continuing failure of plant breeding to provide better alternatives.
Highly client-oriented breeding can produce suitable modern varieties for areas that were dominated by landraces. We examine
here the case of the adoption of two upland rice varieties in three states in eastern India, Jharkhand, West Bengal and Orissa,
where our surveys had confirmed low adoption of modern varieties in the upland ecosystem. The two new upland varieties were
readily accepted by farmers who rapidly adopted them on large proportions of their land. On-farm diversity is maintained by
the need to trade-off among varieties but once a variety with overall superiority was found this incentive was removed. The
new varieties from the client-oriented breeding did not have weaknesses that farmers had to trade-off against their landraces
so they were more likely to replace them. They also replaced older modern varieties. Farmers had previously maintained them
along with landraces because they had to trade-off the higher yield of Kalinga III against the more stable yield of landraces
or the higher yield of Vandana against the higher gain quality of the landraces. Only mean count per household could be used
to test the significance of the differences between individual years. In all states, this revealed a significant reduction
in landrace diversity with the adopting farmers when the addition of the two new varieties was not considered. Trends across
years for mean varietal count, total count and Shannon–Wiener index showed a significant decline in Orissa, irrespective of
whether the two new varieties were included in the analysis or not. In Jharkhand there was a significant decline only for
mean count when the new varieties were not included. In Orissa, it was possible to test if rare landraces were as readily
replaced as more common ones. Landrace replacement was unmitigated by increasing rarity yet the most rare landraces have the
highest priority for genetic conservation. Some landraces were completely replaced by the farmers in the sample despite a
diverse variety portfolio being a risk-reducing strategy in a region where there is a high risk of crop failure. There was
little environmental heterogeneity in the marginal, drought-prone areas to slow this decline. The new varieties had an impact
on the farming system because sometimes farmers brought additional upland into cultivation. They also introduced these varieties
into more favourable, medium land. The strategy of releasing two new upland varieties met with some success in maintaining
diversity. 相似文献
3.
Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae) is an exotic species native to the USA, damaging cotton and other plant families. The
feeding potential of different development stages of Cryptolaemus montrouzieri Mulsant, a biological control agent against mealybugs, was investigated on different development stages of P. solenopsis. Fourth instar grubs and adults of C. montrouzieri were the most voracious feeders on different instars of mealybug. The number of 1st instar nymphs of mealybug consumed by 1st, 2nd, 3rd and 4th instar larvae and adult beetles of C. montrouzieri was 15.56, 41.01, 125.38, 162.69 and 1613.81, respectively. The respective numbers of 2nd and 3rd instar nymphs of mealybug consumed were 11.15 and 1.80, 26.35 and 6.36, 73.66 and 13.32, 76.04 and 21.16, 787.95 and 114.66.
The corresponding figures for adult female mealybugs were 0.94, 3.23, 8.47, 12.71 and 73.40, respectively. The results indicate
that C. montrouzieri has the potential to be exploited as a biocontrol agent in North India; inoculative releases of 4th instar larvae and adults may provide instant control of P. solenopsis. Field experiments should be conducted to determine the efficiency of the ladybird on this mealybug. 相似文献
4.
Harpreet Kaur Virk Guriqbal Singh Gursahib Singh Manes 《Journal of plant nutrition》2018,41(9):1184-1196
A field experiment was conducted to study the effect of different planting methods (Happy Seeder sowing, Straw Chopper + Zero Tillage sowing, and conventional sowing) and nitrogen (N) levels (0%, 75%, 100%, and 125% of recommended N) on the emergence, growth, symbiotic parameters, productivity, and profitability of soybean sown after wheat harvest. Growth and symbiotic parameters were significantly better under Happy Seeder sowing and Straw Chopper + Zero Tillage sowing than conventional sowing. The seed yield, nutrient uptake, and economic returns were significantly higher under Happy Seeder sowing than other methods. The growth parameters, symbiotic parameters, biological, straw, and seed yields were increased significantly up to 100% recommended N level. The nutrient uptake increased significantly up to 100% recommended N level. Therefore, sowing with Happy Seeder after combine harvested wheat along with 100% recommended N would best optimize soybean yield and profitability. 相似文献
5.
Daljit Singh Virk 《Journal of Crop Improvement》2017,31(1):1-24
The analysis of residuals computes general adaptabilities (GAs) and specific adaptabilities (SAs) of genotypes similar to combining ability analysis. The residual analysis is simple and robust being based on the first-degree statistics, and is assumption-free. A unique statistic of ratio of variances (VR) of residuals for individual genotypes allows comparing their stability. The residuals analysis of genotype × environment (GE) interactions was performed for grain yield (t ha?1) of 25 rice (Oryza sativa L.) genotypes, including two developed by marker-assisted selection for root traits quantitative trait loci (QTL), tested across 16 sites. Results were compared with the linear regression analysis for (i) full set of 16 sites showing adequacy of linear model and (ii) subset of nine-poor sites showing inadequacy of linear model. There was agreement between the two analyses for situation (i) but not for situation (ii) when the regression analysis fails because of nonlinearity but the residual analysis retains its validity. 相似文献
6.
7.
Cytoplasmic differentiation using near-isonuclear polycytoplasmic male sterile lines in pearl millet
Summary Five near-isonuclear polycytoplasmic versions of 81A1 and two of Pb 402A3 male sterile lines of pearl millet (Pennisetum typhoides), along with their corresponding maintainer lines (81B and Pb 402B) were studied for 14 agronomic and two disease traits, and for isozymes of peroxidase in anthers and leaves for assessing cytoplasmic differences. Significant differences among isonuclear polycytoplasmic lines of both 81A1 and Pb 402A3, having the same genome and variable cytoplasms, were observed for several agronomic traits. Banding pattern of peroxidase isozymes revealed clear cut differences among cytoplasms. The results provide evidence for the influence of cytoplasmic factors on the phenotypic expression of nuclear genes. 相似文献
8.
Number of crosses and population size for participatory and classical plant breeding 总被引:3,自引:4,他引:3
In the breeding of self-pollinating crops, crossing creates variation upon which selection is exerted. If the value of crosses
cannot be predicted then this uncertainty means that many crosses need to be made. However, since there is a limit to the
capacity of a breeding programme, more numerous crosses result in each cross having a small population size, fewer progenies
in later generations and a lower probability of recovering good genotypes from each cross. Published theory on the optimum
number of crosses in a plant breeding programme, for a predominantly self-pollinating crop, usually assumes that all crosses
are equal value. This overestimates the number of crosses required. When the optimum size of a population in a favourable
cross is considered, theory predicts that very large populations are desirable. The required population size is even larger
if linkage of loci controlling different traits is also considered. Hence, in an inbreeding crop, one possible strategy is
to select a small number of crosses that are considered favourable and produce large populations from them to increase the
probability of recovering superior genotypes. In an out breeding crop, the analogy is a few composites with large population
sizes. This low-cross-number strategy is ideally suited to the particular constraints and advantages of participatory plant
breeding. Such an approach, although not essential, may still be advantageous in classical breeding. When a breeding programme
is based on few crosses, which parents are chosen is crucial and farmer participatory methods are highly effective in narrowing
the choice. Modified bulk population breeding methods, and recurrent selection are desirable strategies in the participatory
plant breeding of self-pollinating crops when combined with a low-cross-number approach.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
9.
Progress in ideotype breeding to increase rice yield potential 总被引:20,自引:1,他引:19
Shaobing Peng Gurdev S. Khush Parminder Virk Qiyuan Tang Yingbin Zou 《Field Crops Research》2008,108(1):32-38
The ideotype approach has been used in breeding programs at the International Rice Research Institute (IRRI) and in China to improve rice yield potential. First-generation new plant type (NPT) lines developed from tropical japonica at IRRI did not yield well because of limited biomass production and poor grain filling. Progress has been made in second-generation NPT lines developed by crossing elite indica with improved tropical japonica. Several second-generation NPT lines outyielded the first-generation NPT lines and indica check varieties. China's “super” rice breeding project has developed many F1 hybrid varieties using a combination of the ideotype approach and intersubspecific heterosis. These hybrid varieties produced grain yield of 12 t ha−1 in on-farm demonstration fields, 8–15% higher than the hybrid check varieties. The success of China's “super” hybrid rice was partially the result of assembling the good components of IRRI's NPT design in addition to the use of intersubspecific heterosis. For example, both designs focused on large panicle size, reduced tillering capacity, and improved lodging resistance. More importantly, improvement in plant type design was achieved in China's “super” hybrid rice by emphasizing the top three leaves and panicle position within a canopy in order to meet the demand of heavy panicles for a large source supply. The success of “super” hybrid rice breeding in China and progress in NPT breeding at IRRI suggest that the ideotype approach is effective for breaking the yield ceiling of an irrigated rice crop. 相似文献
10.
On-farm varietal biodiversity was studied through household surveys in two high potential production systems in Chitwan and
Nawalparasi districts of the Nepal Terai and in Lunawada sub-district, Gujarat, India. Diversity was extremely low in Chaite rice in the Nepal study area (weighted diversity 0.04) and low in main season rice in the India study area (weighted diversity
0.34). In both areas, one cultivar dominated, CH 45 in Nepal and GR11 in India. In the India study area, biodiversity varied
with the socio-economic group and better-off farmers had a greater varietal diversity. Participatory varietal selection (PVS)
identified new varieties that farmers preferred. Their adoption by farmers increased on-farm varietal biodiversity within
the three cropping seasons studied. Despite the commonly assumed uniformity of high potential production systems, the new
varieties occupied specific niches in the farming system. Farmers' preferences for different varieties – there were large
differences in quality traits and maturity period among the new varieties – should help to maintain biodiversity. Overall
production is expected to increase as each niche becomes occupied increasingly by the best-adapted variety. PVS is a simple
and powerful method of increasing food production in the high potential production systems that produce most of the developing
world's grain.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献