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41.
The brown planthopper (BPH) is a potent pest of rice in Asia and Southeast Asia. Host resistance has been found to be the most suitable alternative to manage the insect. But varietal resistance has been found to be short-lived. There has been a constant search for alternate resistance genes. We developed an F8 recombinant inbred population for the BPH resistance gene in Salkathi, an indica landrace from Odisha, India. Phenotyping of RILs against the BPH population at Cuttack, Odisha showed continuous skewed variation with four peaks at 2.1–3.0, 4.1–5.0, 6.1–7.0 and 8.1–9.0 SES score, suggesting the involvement of quantitative loci for resistance to BPH in Salkathi. Mapping showed the presence of two QTLs on the short arm of chromosome 4. One QTL, with phenotype variance of 37.02% is located between the markers RM551 and RM335. The other QTL, with phenotype variance of 7.1% is located between markers RM335 and RM5633. The two QTLs have been designated as qBph4.3 and qBph4.4. QBph4.3 seems to be a novel QTL associated with BPH resistance. We have successfully transferred qBph4.3 and qBph4.4 into two elite rice cultivars, Pusa 44 and Samba Mahsuri. Fine mapping of the identified QTLs may lead to a successful transfer of QTLs into other elite germplasm backgrounds.  相似文献   
42.
In this investigation, productivity, sustainability and profitability of rice-wheat system were evaluated using the data of a long-term fertility experiment initiated during 1984 at Pantnagar, Uttarakhand, India. Eight treatments (application of N, NP, PK, NK, NPK, NPK + Zn, NPK + FYM and control) were tested in randomized block design. Results revealed that application of NPK + FYM gave the highest and sustainable grain yields for rice, wheat and the system. None of the treatments except NPK + FYM was able to enhance the soil organic carbon content after 31 crop cycles over the initial level. Application of NPK + FYM was the most profitable treatment which provided the highest net return and B: C ratio for rice, wheat and the system. Trend analysis indicated that there were yield declines in all the treatments. Response to P, K and Zn in rice and wheat, and to FYM in terms of system productivity increased over the studied period. The results suggest that continuous application of NPK + FYM would sustain higher yields of rice and wheat over longer period of time with higher profits in rice-wheat system.  相似文献   
43.
Frequency and depth of irrigation play crucial role in crop yield and use efficiency of water resource. To test this hypothesis a field study was carried out in November to January of 2001-2002 to 2003-2004 on a sandy loam (Aeric haplaquept) for quantifying the frequency and depth of irrigation on growth, curd yield (CY) and water use pattern of cauliflower (Brassica oleracea L. var. botrytis). Four irrigation frequencies depending on the attainment of cumulative pan evaporation (CPE) values of: 25 (CPE25), 31(CPE31), 38 (CPE38) and 45 (CPE45) mm were placed in main-plots, with three depth of irrigation (IW) of 35 (IW35), 30 (IW30) and 25 (IW25) mm in sub-plots. Water use efficiency (WUE), net evapotranspiration efficiency (WUEET) and irrigation water use efficiency (WUEI) were computed. Marginal water use efficiency (MWUE) and elasticity of water productivity (EWP) were calculated using the relationship between CY and seasonal actual evapotranspiration (SET). A continuous increasing trend in growth parameters, yield and WUEI was recorded with the increase in SET from CPE45-IW25 to CPE31-IW30. However with further increase in SET the same decreased up to CPE25-IW35 regime. Highest WUE and WUEET obtained under CPE38-IW35 regime where SET value was 5% lower than the status of SET under CPE31-IW30. This study confirmed that critical levels of SET needed to obtain maximum curd yield or WUE, could be obtained more precisely from the knowledge of MWUE and EWP.  相似文献   
44.
The relationship between milk yield and cystic ovarian disease in cattle   总被引:1,自引:0,他引:1  
Studies were conducted to understand the relationship, if any, between the amount and pattern of milk yield and the occurrence of cystic ovarian disease (COD) in dairy cattle. More than 70 cows with cysts were compared with herd mates of similar lactation number. Total milk yield in lactations when cysts occurred and in the preceding lactations were not different from the corresponding lactations in control cows. Patterns of monthly milk yield did not differ between the two groups of cows. However, weekly analysis in early lactation revealed differences. Both groups of cows achieved peak yields at a similar time (5.4 +/- 1.2 vs 5.7 +/- 1.9 weeks post partum in normal vs cows with COD). However, owing to an early decline in yield of cows with COD, their duration of peak yield was significantly shorter (P less than 0.05) than in the control cows (3.2 +/- 2.2 vs 5.6 +/- 2.4 weeks). Both the attainment and the decline of peak yield occurred 5.6 (range = 2-15) weeks before the cysts were diagnosed. It is concluded that COD is not particularly a disease of higher yielding cows and that COD has no discernible effect on the milk yield or its pattern. It is speculated, however, that some cows in early lactation, while trying to meet the requirements of sustained peak milk production, are more susceptible to minor environmental changes (such as new social interactions, or changes in diet). These events may lead to a drop in milk production and disruption of events controlling normal ovulation, resulting in the formation of ovarian cysts.  相似文献   
45.
Functional stay-green (FSG) is characterized by delayed senescence during the reproductive stage in rice. A recombinant inbred line (RIL) population derived from ‘Pusa 677’/‘PSG16’ was used to study the genetics of FSG in a rice mutant, ‘PSG16’. The RILs exhibited significant variation under two N regimes for agro-morphological traits, leaf chlorophyll content, flowering time, yield components and nitrogen (N) use. Using a genome wide linkage map spanning 1910.8 cM with 104 polymorphic markers, we have mapped six major quantitative trait loci (QTLs). One robust QTL on chromosome 1 was associated consistently across different N regimes with chlorophyll content and flowering time. The QTL on chromosome 7 was associated with grain number, whereas the QTL on chromosome 6 was found related to N harvest index and spikelet fertility. Although ‘PSG16’ showed a clear advantage in grain yield as well as having better N assimilation, we could not establish a direct genetic relationship SG trait and N use. Based on the QTL information, FSG trait of ‘PSG16’ could be useful in deciphering multiple stress responses in rice.  相似文献   
46.
Two neem preparations and the bitter‐tasting synthetic chemical denatonium benzoate were tested in the laboratory as antifeedants against the diamondback moth, Plutella xylostella L. The effects of the three materials on Cotesia plutellae (Kurdjumov), a hymenopteran parasitoid of ­P xylostella, were also recorded. All three materials significantly reduced the food consumption of ­P xylostella larvae. Parasitoid cocoons were formed on approximately half of those larvae which had been exposed to female C plutellae, regardless of antifeedant treatment, but emergence of adult parasitoids from the cocoons was significantly reduced by antifeedant treatment. In terms of food consumption and mortality of unparasitised P xylostella larvae, and emergence of adult C plutellae, the effect of each antifeedant preparation was directly related to the concentration of material used, but the effects of the neem preparations were greater than those of denatonium benzoate. However, no adult P xylostella emerged on any antifeedant treatment, therefore some of the parasitoids survived antifeedant treatments which were fatal to the unparasitised hosts. © 2000 Society of Chemical Industry  相似文献   
47.
A simple, sensitive, and rapid method is described for the quantitative estimation of ng amounts of parathion (O,O-diethyl O-p-nitrophenyl phosphorothioate) as paraoxon (O,O-diethyl O-p-nitrophenyl phosphate) on thin layer chromatograms. Paraoxon is detected by inhibition, using p-nitrobenzenediazonium fluoroborate as the chromogenic reagent. This chromogenic reagent is more sensitive than Fast Blue B or indoxyl acetate; 0.1 ng may be detected and amounts from 5 to 50 ng may be estimated. The method is a viable alternative to gas chromatographic analysis for parathion.  相似文献   
48.
Inheritance of Karnal bunt-free trait in bread wheat   总被引:1,自引:0,他引:1  
A Karnal bunt (KB)‐free wheat stock (‘KBRL22’) obtained from a cross of two resistant lines (‘HD29’ and ‘W485’) was used as a donor to introgress the KB‐free trait into ‘PBW343’(an ‘Attila’ sib), the most widely grown wheat cultivar in India. The number of KB‐free and KB‐affected plants in BC 1, BC2, BC3 and BC4 as well the F2 was recorded after artificial inoculations. The segregation pattern in these generations clearly indicated two independently segregating, dominant genes which jointly confer the KB‐free attribute. The importance of the KB‐free line generated in this experiment is discussed.  相似文献   
49.
Summary The variation among the component lines of the KSML 3 (a multiline based on cultivar Kalyansona, spring bread wheat) was studied for agronomic characteristics. For days to earing and plant height the variation was small. This helped in imparting uniformity to the multiline. The lines had an improved tillering ability and had larger seeds. This partially explained the increased yield potential of the multiline as compared with Kalyansona.All the lines were susceptible only to one or two races of the yellow and brown rust. In no case any race was virulent against all the lines. In the field all the lines were resistant to both rusts.  相似文献   
50.
An experiment was conducted to study regrowth and yield of coriander influenced by nitrogen (N) with five different urea doses (0, 1.5, 2.0, 2.5, 3.0% by volume) as foliar spray. Spraying of urea has a significant impact on growth and yield in the second cut. Leaf emergence rate (LER) was higher during initial growth phase and then drastically reduced until first cutting, whereas the stem elongation rate (SER) recorded its peak value during 75-105 DAS. Impact of foliar spray was conspicuous during the later phase of regrowth with the treatment of 2.5% urea achieving the highest SER. Additional return due to spraying was positive up to a dose of 2.5% urea and decreased thereafter. Hence, the study indicated that a foliar spray of nitrogen (2.5% urea) may be beneficial for coriander leaf production under multicut system and the crop is sensitive to rainfall, phototemperature, and morning humidity.  相似文献   
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