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951.
952.
Transfer of Tomato Leaf Curl Virus Resistance from Lycopersicon hirsutum f. glabratum to L. esculentum 总被引:1,自引:0,他引:1
Six lines, i.e., H-2, H-11, H-17, H-23, H-24, and H-36, resistant to Tomato Leaf Curl Virus (TLCV) have been developed with controlled introgression of L. hirsutum f. glabratum into Lycopersicon esculentum. The disease incidence, 120 days after inoculation, of those lines derived from L. hirsutum f. glabratum ranged from 8.3 to 35.0 %, whereas in susceptible varieties it ranged from 95.0 to 100 %. The coefficient of infection (CI) values in the resistant lines were very low, ranging from 0.25 to 4.55, whereas in susceptible varieties CI values ranged from 60.56 to 88.96. Line H-2 had the highest resistance by showing the least disease incidence and CI values. The fruit size and days to maturity in resistant lines were close to those of cultivated susceptible varieties. These lines have the scope for being used as varieties in the TLCV infested areas or as foundation lines for further genetic improvement. 相似文献
953.
Experiments were undertaken to identify an efficient method of selection for yield in early segregating generations of narrow-leaf lupin crosses. A first series of experiments involved simulation of F2 populations with mixtures of ten cultivars and advanced breeding lines. The performance of genotypes in mixtures sown at different densities was compared with their monoculture [commercial density) yields m the same and the following year. These comparisons provided a basis for assessing the value of different planting designs and different selection criteria in early generation selection for yield. Correlated monoculture yield responses to simulated selection for single plant yield were similar for the honeycomb design and standard selection procedures at both low and commercial densities. These responses were much higher than that for grid selection in a low density population. Correlated monoculture yield responses to selection for other plant characters were substantial only for flowering time and number of pod bearing branches under certain conditions. These responses were greatest for selection in a low density mixture and in the year following selection. A procedure involving selection of the earliest flowering plants and selection within this group of plants with the highest number of pod bearing branches should be an effective approach to early generation yield selection in the narrow-leaf lupin. 相似文献
954.
The Effect of Chromosome 1B/1R Translocation on the Yield Potential of Certain Spring Wheats (Triticum aestivum L.) 总被引:2,自引:0,他引:2
Nearly 50 percent of the 1988 advanced breeding lines of the CIMMYT bread wheat breeding program possess the 1B/1R homozygous translocation. Hence, a trial was conducted to estimate the effect of 1B/1R chromosome translocation on the yield potential of some of our high-yielding spring wheats, where non-limiting levels of fertility, moisture, preventive pest and disease programs were used. In conclusing the 1B/1R lines seemed to have increased their above-ground biomass yield, number of spikes per meter2, 1000-grain weight and test weight. They also exhibited a slight advantage over the 1B homozygous lines on grain yield. The observed difference, however, was non-significant, as was the plant height difference observed among the two groups. Varietal comparisons indicated that the 1B/1R group headed later than the 1B group. 相似文献
955.
Summary A series of international trials with the potato crop was conducted in eight countries representing widely differing environments. The purpose of the experiments was: (1) to develop a method for obtaining environmental indexes which measure productivity of diverse potato-growing areas, and (2) to construct performance models for individual genotypes based on the environmental indexes. Yield data of 32 genotypes obtained from a series of 13 experiments conducted in the eight countries in 1983 and 1984 were used in the study. The response pattern of the genotypes was studied by a multivariate analysis. Five genotypes were chosen as representatives for different response patterns to the environments and their data were used for calculating a series of independent indexes for each of the experimental sites based on principal component analysis. Performance models for each of the genotypes were constructed by stepwise regression analysis of yields of a genotype on the environmental indexes based on 1983 data. Yield data of 1984 experiments were used to verify the models. Satisfactory correspondence between observed and predicted yields was obtained for most of the genotypes. 相似文献
956.
Different improved coffee arabica crosseshaving resistance to coffee berry diseaseand leaf rust, plus a standard cultivar,were grown under a range of environmentalconditions in a series of field trials inKenya. The effects of location and year ofproduction and their interactions with theclones were determined for berry yield.These data were used to estimate andcompare methods of analysis of GEI. An AMMImodel, joint regression model and ANOVAwith repeated measurements were used toinvestigate these interactions. The resultsindicated the relative effects of theclones and the environmental conditions,with Meru being the location where therewas greatest discrimination between theclones, probably because it was bettersuited for coffee. Clones,environments and joint regressions combinedaccounted for 31.20% of the interaction,leaving a residual of 68.80%. Significantresidual mean squares showed therelationship between clones andenvironments not to be strictly linear,thus indicating that regression analysisdid not always provide good estimates ofindividual clonal performance acrossenvironments. High correlations wereobtained between mean yield and regressioncoefficients and between ecovalence andmean square deviations as well as thecoefficient of determination. Resultsshowed that the improved clones surpassedthe standard cultivar both in terms ofyield and stability.Different analyses of the various aspectsof genotype response enabled the 21 clonesto be classified into different similaritygroups based on their performance andphenotypic stability as measured by variousstability parameters and the use of biplotsfrom the AMMI analysis. 相似文献
957.
Fuzzy controller can achieve satisfactory dynamic performance even for complicated process without mathematical model of the process.Its main imperfection is the existence of steady state error and ultimate oscillatory in the process output. This limits its application area. How to eliminate the steady state error while keep its good dynamic performance has been paid much attention. The strategy to introduce integral function to the conventional fuzzy control system is put forward in this paper to overcome the above problem. After expound two key factors on introducing integral action,an intelligent integral algorithm has been employed,and two methods on introduction of the intelligent integral to the fuzzy control system are proposed. Their characteristics and applied situations are summarized. 相似文献
958.
959.
960.
This paper presents a new steering-gear performance test calculation formula,and set up a corresponding test system on this basis,and obtain a preliminary test result. 相似文献