Betting The Farm On Racehorse Hybrids. (6076)
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Corn seed agronomists often talk about and suggest growers plant these hybrids on their best producing soils. They imply that hybrids yield higher than other hybrids in high yielding environments. We questioned whether hybrids exist among commercially available corn hybrids. If so, what is their yield advantage in high yielding environments and how do they perform in low yielding environments? A total of 13,174 corn hybrids grown at three or more locations from 1,904 experiments conducted by several Midwest university corn performance trial programs were evaluated to determine yield response over environments. The concept of racehorse and stable hybrids will be presented and discussed relative to a grower's management decision of choosing hybrids for their farm. Only 3-4% of the hybrids tested could be classified as hybrids.Keywords:
Plant Breeding
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The development of F1 hybrids or inbred lines is a dilemma faced by many rice breeders. Rice F1 hybrids have an average yield advantage of about 15% over the best inbred cultivars but they have some disadvantages. Firstly, they do not breed true and they lose the yield advantage in subsequent generations. Secondly, they are more susceptible than inbred lines to the major diseases and insect pests. Thirdly, their seed production cost is 10-15 times higher than that of ordinary seeds and finally they are generally inferior to the best conventional cultivars in the main quality traits such as grain size, vitreosity, milling yield. Results obtained when F1 rice hybrids were compared with recombinant inbred lines led to the conclusion that application of combined selection for yield and quality could produce recombinant inbred lines with equal yielding ability and equal or higher quality than the F1 hybrids. Similar results were obtained in other self-pollinated crops such as tomato, Nicotiana rustica, barley and cotton. F1 hybrids should hardly be seen as finished forms of cultivars. They should mainly serve as bridges to develop the most advanced forms, i.e., pure line cultivars. It is concluded that in the developed world F1 rice hybrids are not justified to be a breeding goal but just an intermediate step for breeding of even better inbred cultivars. In contrast, in the developing world the release of F1 rice hybrids is justified and they can play a significant role until their seed production cost and quality will become limiting factors. (Resume d'auteur)
Inbred strain
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Germ plasm
Plant Breeding
Inbred strain
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The topic was hybrid corn. In 1949, the open pollinated varieties of sweet corn are gradually being replaced by improved sweet corn hybrids. Varieties of poor as well as excellent quality exist in both open pollinated and hybrid sorts. Although the best open pollinated varieties are better than many hybrids, they are generally inferior to the better hybrids in the various maturity seasons. For a complete succession of maturities, five selected hybrids
would mature over a period of about four weeks.
Open pollination
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Grain sorghum hybrids, which promise to
meet the pressure for more efficient production
much as corn hybrids met a similar need 25 years
ago, will be grown by American farmers on a
limited scale this year. Tests of selected hybrids
in sevenstates showed a substantial increase over
the production of standard varieties of similar
maturity in 1954 and 1955.
Caution is advised in making seed purchases -- farmers should buy only tested hybrids. Initial
plantings of hybrids should be grown with standard
varieties for comparison.
Continuing research will result in improved
hybrids and will indicate the areas best suited to
each.
Plant production
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In 1967, selected standard 75 to 105 relative maturity open pedigree corn hybrids and new hybrids were tested annually for grain and silage yields in
agronomy plots at Fargo, North Dakota. Those attributes which make corn hybrids more dependable are presented in this article.
Silage
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Data on the level of heterosis for grain yield under Australian dryland wheat growing conditions is essential before any decision can be made to commit resources to hybrid wheat breeding. Experiments were conducted at Narrabri, N.S.W., to determine the level and stability of heterosis for grain yield expressed by F1 hybrids derived from crosses of adapted Australian varieties. The hybrids and their parents were grown in hill plots in replicated experiments at three sowing times for two years (six environments). The hybrids outyielded their parents in each of the six environments with levels of mid- and high-parent heterosis up to 31.5 and 26.8%, respectively. The best hybrid outperformed the best check variety by an average yield margin of 18.2%. The hybrids were marginally but not significantly more stable in their yield performance across environments than their parents. While heterosis for grain protein content was generally negative, some hybrids were superior to the check varieties for both grain yield and protein content. Yield component analysis revealed no consistent pattern by which the best hybrids obtained their yield advantage over their parents. The levels of heterosis and the absolute yield advantage displayed by the hybrids over the best pure line check varieties were sufficient to sustain the commercial production of hybrid wheats in northern N.S.W.
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Despite having a history of over a half a century in the production and distribution of hybrids in India, Sri Lanka and Ivory Coast and over 30 years in most other countries, the achievements have so far not become manifest either in the global output of coconut oil or in its export volume. Different combinations of Tall x Tall types have been evolved in Indonesia, Ivory Coast, Sri Lanka, Thailand, Vanuatu etc. and the experience in these countries is that Tall x Tall hybrids are superior to the open pollinated progenies of tall but, in general, they do not out-yield intervarietal hybrids. A large number of intervarietal hybrids are now available in all the coconut growing countries for cultivation by the farmers. In a Farmer Participatory Research conducted in Kerala State, India in 1998 the general assessment of farmers was that the hybrids are precocious, medium statured and productive under good management. At the same time they do not tolerate harsh soil and climatic conditions, are more prone to pest and disease attack and fail to produce normal yield of nuts under average management. In this study the hybrids were rated best only in early bearing and production of more number of nuts. As regards to preference of farmers, it was only 5.3% for hybrids and in future plantings, hybrids will form only 5-6%. APCC has conducted two studies, one in 1988 and the other in 1998, to assess the experience of farmers with high yielding varieties of coconut including hybrids. In the first study there were 740 responses of satisfaction of which 410 or 55% were in favour of hybrids. However, there were also 457 responses of dissatisfaction of which 243 or 53.2% were attributed to hybrids. Slight improvement in the degree of satisfaction with hybrids was observed in the 1998 study. Hybrids scored 70% favourable responses against 55% of the previous study. Similarly, the responses of dissatisfaction with hybrids showed a marginal decline to 235 from 243 of the previous study. In the 1998 study, varietal preference of farmers for future plantings was recorded through 381 responses. Of the total, 55.6% were in favour of planting hybrids, 28% were in favour of planting local talls and/ or selected talls and the remaining were for dwarf and miscellancous other types. Proper extension education and services are essential to make the farmers conscious of the management needs of hybrids for reaping the expected benefits from their cultivation. It is also important to evolve better hybrids possessing higher production potential and devoid of undesirable traits for introducing to low external input farming situations. (Resume d'auteur)
Sri lanka
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Abstract In the maize producing regions of Sub-Saharan Africa (SSA), compounding effects of genotype-by-environment interaction have necessitated breeding maize for outstanding performance and stability across varying environments. This study was conducted to assess the performance and stability of late-maturing cultivars and their respective hybrids evaluated under contrasting environments in the tropical rainforest region. We evaluated 108 genotypes in field trials under three different growing conditions in 2018 involving 14 open-pollinated parents and their hybrids derived from a diallel mating design. The genotypes were evaluated under field conditions using 9 × 12 alpha lattice design with three replications in six environments. The genotypes were divided into three groups, containing either the parents, hybrids or checks, for estimating the stability variance and grain yield. The difference between the lowest and highest yielding environment was 3.9 t ha −1 , while the repeatability of the grain yield trials ranged from 39 to 80%. The average grain yield of the hybrids (2.33 t ha −1 ) was significantly higher than that of the parents (2.19 t ha −1 ) and the check varieties (2.03 t ha −1 ). The hybrids were more stable than both the parents and the checks. They also showed a higher stability against a common group of the parents and checks. The results of this study suggest that high yielding and stable population hybrids can be utilized in breeding programmes aiming to provide improved varieties for the large number of rural maize farmers in the SSA zone, who often lack access or the capacity to purchase commercial hybrids.
Open pollination
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The results of studies on the major agronomic traits of the best com hybrids of different maturity groups on their suitability to grow in south-western part of the forest- steppe. Use in production practice the proper Selection of hybrids of maize provides an opportunity not only to predict the volume of its production, but also significantly save energy at the post-harvest handling of grains of this crop.
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In the past years, few grain sorghum varieties with limited yield potential have been developed and grown in Korea. Hybrids tend to be more productive and resistive to unfavorable environmental conditions than pure line varieties. However, no hybrid cultivars are available and never have been planted for grain sorghum in Korea. The main aims of this study were to (i) verify if US x Korean and US x US hybrids increase grain yield in Korea; (ii) assess the performance of waxy hybrids in Korea and the US; (iii) estimate general combining ability and specific combining ability for the lines studied; and (iv) identify superior lines and hybrids for future use in breeding. Two distinct sets of waxy-endosperm sorghum hybrids derived from Korean landraces and US lines (Texas A&M University) were tested in the US and Korea. Compared to the parental lines, hybrids derived from US lines and Korean landraces showed yield increase that ranged from 2% to 127%. Hybrids created from US lines showed higher heterosis than US x Korean hybrids. Hybrid vigor was observed in the US and Korea, but shifts in ranks of hybrid performance occurred. The results indicate that it is feasible to develop grain sorghum hybrids adapted to Korean conditions only if delibrate selections take place in Korea. A combination of Korean and US sources could provide an acceptable germplasm base for developing Korean landrace based sorghum hybrids.
Sorghum bicolor
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