205 research outputs found
Combining PPB and marker-assisted selection: strategies and experiences with rice
Participatory plant breeding should not preclude the use of modern biotechnological techniques
ICRISAT hybrids and varieties in 1987
This paper concerns released and promisimg hybrids and varieties from ICRISAT. In the case of released hybrids and varieties attention is focused on certified seed production and for WC-C75, a survey on farmer acceptance is reported..
The variability in the yield of pearl millet varieties and hybrids in India and Pakistan
The International Peal Millet Adaptation Trial (IPMAT) which has both hybrids and varieties as entries, has been grown multilocationally in India and Pakistan..
Estimates of stability for comparing varieties
For purposes of comparison of analytical methods the yield data on pearl millet hybrids and varieties for five years from locations in India and Pakistan have been analysed using a regression analysis and a meanstandard deviation analysis. The results of the mean-standard deviation analysis and the regression analysis were similar whether carried out on all environments, or on the highest- and lowest-yielding sets of environments. This was substantiated by the remarkable correlation between the slopes from the regression analysis and the standard deviations whatever environmental set was considered. The validity of using a single year's across location data with the mean-standard deviation analysis, if choice-theoretic criteria are used, was examined. It is concluded that, although further confirmation is required, single-year data seem to suffice. The relative merits of the mean-standard deviation analysis and a regression analysis are discussed; the choice-theoretic framework of the mean-standard deviation analysis is advantageous and complementary to the regression analysis
Pearl millet molecular marker research
The slow magic of agricultural research relies on accumulation of knowledge that future generations of scientists can use. New technologies, such as molecular markers, are expensive to develop, and returns from the research take a long time. However, once the knowledge reaches a critical level, gains accelerate and provide a deeper, more flexible, resource. Research on molecular markers to aid in breeding pearl millet [Pennisetum glaucum (L.) R. Br.] for resistance to the downy mildew pathogen Sclerospora graminicola (Sacc.) J. Schrot., which has been largely funded by the Plant Sciences Research Programme of the UK's Department for International Development (DFID), provides a classic example
Plant breeding can be made more efficient by having fewer, better crosses
BACKGROUND: Crop yields have to increase to provide food security for the world’s growing population. To achieve these yield increases there will have to be a significant contribution from genetic gains made by conventional plant breeding. However, the breeding process is not efficient because crosses made between parental combinations that fail to produce useful varieties consume over 99% of the resources. RESULTS: We tested in a rice-breeding programme if its efficiency could be improved by using many fewer, but more judiciously chosen crosses than usual. In a 15-year programme in Nepal, with varietal testing also in India and Bangladesh, we made only six crosses that were stringently chosen on complementary parental performance. We evaluated their success by the adoption and official release of the varieties they produced. We then modelled optimum cross number using assumptions based on our experimental results. Four of the six crosses succeeded. This was a fifty-fold improvement over breeding programmes that employ many crosses where only about one, or fewer, crosses in 200 succeed. Based on these results, we modelled the optimum number of crosses by assuming there would be a decline in the reliability of the breeder’s prediction of the value of each cross as more crosses were made (because there is progressively less information on the traits of the parents). Fewer-cross programmes were more likely to succeed and did so using fewer resources. Making more crosses reduced the overall probability of success of the breeding programme. CONCLUSIONS: The efficiency of national and international breeding programmes would be increased by making fewer crosses among more carefully chosen parents. This would increase the number of higher yielding varieties that are delivered to farmers and hence help to improve food security
Structure of variation among morphological and physiological traits in three pearl millet composites
The plant breeder's task of improving and stabilizing many plant traits simultaneously is complicated by interrelationships that occur among the traits. Factor analyses were conducted on three phenotypically diverse pearl millet [Pennisetum glaucum (L.) R. Br.] composites to describe the structure of relationships among yield, morphological, and physiological traits. Approximately 1000 S0 spaced-plants from each composite were evaluated for 20 traits, and random samples of 289 S1 progenies from each composite were evaluated for 18 of these traits. Factors extracted in S0 and S1 populations identified unique sets of traits that were interrelated along axes of (a) biological yield, (b) panicle size, (c) dry matter partitioning and (d) compensation between number and size of seeds. Several plant traits had large loading coefficients on the ‘Biological Yield’ and also, but with opposite signs, on the ‘Dry Matter Partitioning’ factor. The traits having large loading on these two factors differed between space-planted and normal-density stands, showing that environmental conditions contributed to the associations observed among traits. Correlations of S1 with parental S0 factor scores for the ‘Biological Yield’, ‘Panicle Size’ and ‘Seed Paramters’ factors produced significant correlation coefficients, indicating that these trait complexes had a genetic basis. The implications of these results for millet breeding are discussed
Adoption of rice varieties - I. Age of varieties and patterns of variability
SUMMARYFarmers who continue to grow old and obsolete varieties do not gain the benefits they could get from growing newer ones. Given the potential large scale of these foregone benefits, relatively few studies have examined the age of varieties that farmers grow. In three surveys, members of over 3300 households were interviewed to find the rice varieties they grew in 2008 and 2011 in 18 districts in the Terai, the low-altitude region of Nepal. This provided the first description of detailed geographical patterns of adoption of rice varieties and their ages that were repeated over time. There were large differences between district and individual varieties that showed specific geographical patterns of adoption. Such detailed knowledge on spatial diversity of varieties is invaluable for planning extension activities and developing breeding programmes, and cheaper ways than household surveys of collecting this information are discussed. Some of the factors considered important in determining this complex pattern of adoption were seed availability, growing environments that differed from east to west and the continued popularity of varieties once they had established markets. Rice diversity was low because a small number of rice varieties occupied large areas. In 2011, nine varieties covered at least 75% of the total rice area in western districts, just four in central districts and eight in eastern districts. Of these, most were released before 1995 resulting in a high average age of the predominant varieties – they always had an average age of over 20 years no matter which region or year was considered. Even though there were some large changes in varietal composition from 2008 to 2011, the average age of the predominant varieties remained almost the same. In a second paper in this series, we examine how these very low varietal replacement rates, that reduce yields and increase risk to farmers, can be accelerated using a participatory research for development approach called Informal Research and Development (IRD) (Joshi et al., 2012).</jats:p
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