Open-pollinated Cultivars Research Articles

Utilization of Hybrid Vigor in Broomcorn, Sorghum bicolor (L.) Moench

The current commercial broomcorn (Sorghum bicolor (L.) Moench) production is based on open-pollinated cultivars. Having in mind the the success of F1 hybrids in the case of grain sorghum, the purpose of this study has been to estimate the hybrid vigor in broomcorn. Locally adapted broomcorn inbred lines were selected for hand crossing in order to obtain experimental Fl hybrids. Six cytoplasmic-genic male sterile lines were used as male parents and croseed with six pollinators using the line x tester model. The resulting 36 experimental Fl hybrids along with their parents were studied for plant height and its components as well as for weight and quality of panicle. Hybrid vigor was calculated and the best performing hybrids were identified. The line x tester analysis provided the estimation of gene effects for different quantitative traits. The correlation between the performances of parental lines as compared to their hybrids was also calculated. The results indicate that broomcorn demonstrate a positive hybrid vigor for most of the characters studied. Due to the prevailing additive gene effect for most of the characters studied the best performing hybrids were those involving superior parental lines.

Agronomic performance of different stature sunflower cultivars under different levels of interplant competition

Early-maturing, short-stature sunflower (Helianthus annuus L.) cultivars improve the adaptability of sunflower to the short growing season of western Canada. However, the agronomic potential of the recently developed dwarf cultivars in comparison to standard-height sunflower is yet to be understood. Multi-environment field studies, consisting of space-planted trials, where interplant competition was low, and agronomy trials, where plants were grown at commercial population densities, were conducted in southern Manitoba to compare the yield formation of dwarf hybrids (sunwheats; SW-101 and SW-103), and dwarf open-pollinated c ultivars (sunola; Aurora and Sierra) with that of standard-height cultivars (IS-6111 and SF-187). In space-planted trials, dry matter (DM) accumulation and water use efficiency for dry matter production (WUEDM) decreased as plant height decreased. In agronomy trials, differences in DM and WUEDM among the different height classes were masked. The diversion of assimilate from stem to head depended on the genetic background, while the efficiency of utilising assimilate in the head for seed production was lower in dwarf cultivars. Only one of the four dwarf cultivars (SW-103) displayed a higher harvest index than IS-6111. Higher seed yield for the standard-height cultivar, IS-6111, and the dwarf open-pollinated cultivar, Aurora, compared to other cultivars was attributed to both greater DM and improved DM partitioning. However, variations observed among the dwarf cultivars for DM accumulation and partitioning revealed that the dwarfing gene was not a limiting factor for breeding a dwarf sunflower cultivar with better partitioning of DM along with better yield potential. Key words: Dwarf sunflower, Sunola, seed yield, biomass, water use efficiency

Rendimiento y calidad de fruta en cultivares de papaya en dos localidades en Puerto Rico.

Cinco híbridos y un cultivar de polinización abierta de papaya se evaluaron en dos localidades en un suelo Oxisol (Isabela) y Ultisol (Corozal) bajo manejo intensivo. En Isabela, el híbrido Tainung 3 produjo el mayor número de frutas comerciales, mientras que en Corozal los tres híbridos Tainung no mostraron diferencias significativas para esta variable. En ambas localidades los híbridos Red Lady, Known You 1, Tainung 1 y Tainung 2 no mostraron diferencias significativas en el peso de frutas comerciales. El peso medio de frutas comerciales en estos híbridos fue 134,585 kg/ha en Isabela y 75,256 kg/ha en Corozal. El cultivar PR 6-65 produjo frutas significativamente más grandes en ambas localidades, mientras que el híbrido Tainung 3 produjo las frutas de menor tamaño. En ambas localidades los valores debrix fueron significativamente más altos en frutas del híbrido Tainung 3 y más bajos en las frutas de PR 6-65.

Distribution of S haplotypes in commercial cultivars of Brassica rapa

AbstractSelf‐incompatibility in Brassicaceae plants is sporophytically controlled by a single multi‐allelic locus (S locus), which contains at least three highly polymorphic genes expressed in the stigma (SLG and SRK) and in the pollen (SCR/SP11). Using polymerase chain reaction‐restriction fragment length polymorphism (PCR‐RFLP) analysis with SXG‐specific primer pairs, the S haplotypes of F1 hybrid and open‐pollinated commercial cultivars of Brassica rapa were identified. The number of S haplotypes detected in the F1 hybrid cultivars of Chinese cabbage, komatsuna, pak‐choi, turnip, open‐pollinated cultivars of Chinese cabbage and turnip were 9, 9, 4, 11, 13 and 12, respectively. Nine of them had different PCR‐RFLP profiles from those of the S‐tester lines that determined the SLG sequences. Four SLG sequences in the F1 hybrid cultivars were determined and named S53, S54, S55 and S56, respectively. It is demonstrated that the PCR‐RFLP analysis using specific primer pairs of SLG and SRK is useful for identification of the S haplotypes, in both, S homozygous and S heterozygous plants of B. rapa. The possibility of using this method routinely in breeding programmes, and in the evaluation of F1 hybrid seed purity, is discussed.

Genetic and Environmental Variation for Tomato Flesh Color in a Population of Modern Breeding Lines

The genetic and environmental variation for flesh color of tomato (Lycopersicon esculentum Mill.) fruit was quantified using 41 red-fruited breeding lines, open-pollinated cultivars, and hybrids that are representative of the diversity of tomatoes grown for whole-peel processing in the midwestern and eastern United States and Ontario, Canada. Objective color measurements were made for 2 years from replicated experiments with 2 to 4 blocks per year. Genotypes differed significantly in lightness value (L*), saturation (chroma), and hue angle. Variation within fruit and among fruit in plots accounted for more than 75% of the environmental variation for the color traits. The crimson locus (ogc) accounted for less than one-third of the variation in fruit color among genotypic means, and explained 18% to 27% of the genotypic variation for L*, chroma, and hue. Estimates of variance components were used to develop sampling strategies for improving selection efficiency. Genotypes were identified that may be useful for studying genetic differences that lead to quantitative variation for fruit color in red-fruited populations of tomato.

Canola pollination: an update

This update highlights what is currently known about nectar and pollen production of hybrid and open-pollinated canola and rapeseed cultivars and varieties, the activities of foraging insects, specifically honey bees (Apis mellifera), on the flowers and pollinator requirements for seed production. Readers can also find further information in previous reviews92,93 and several excellent books27,49,97,98.

Maturity Studies in Hybrid and Open Pollinated Cultivars of Maize

Maturity Studies in Hybrid and Open Pollinated Cultivars of Maize

Effects of planting pattern of collards on resistance to whiteflies (Homoptera: Aleyrodidae) and on parasitoid abundance.

Fourteen collard entries, Brassica oleraceae L., Acephala group, were evaluated for resistance to natural populations of Bemisia argentifolii Bellows & Perring in replicated field plots in Charleston, SC. Glossy-leaf phenotypes ('SC Glaze', 'SC Landrace,' 'Green Glaze') were the most resistant collard entries and had fewer whiteflies than the nonglossy, open-pollinated cultivars. Also, two F1 hybrid cultivars with normal, nonglossy leaves ('Blue Max' and 'Top Bunch') were resistant. In laboratory experiments, there were no differences in the intrinsic rate of growth (rs) of B. argentifolii populations on either glossy or nonglossy collard phenotypes. Over a 2-yr period, there were no differences in the abundance of whiteflies on the glossy phenotype of Green Glaze when it was planted in solid 20-plant plots or when it was alternated (every other plant) with the nonglossy phenotype of Green Glaze. In a similarly designed experiment, there was no difference in the resistance of Blue Max in either solid or mixed planting scheme compared with the susceptible 'Morris Heading'. Higher numbers of whiteflies and parasitoids (primarily Eretmocerus spp.) were collected on yellow sticky cards in the solid plantings of the nonglossy phenotype of Green Glaze than were collected in the solid plantings of the glossy Green Glaze phenotype. Counts on sticky cards in the mixed plots were intermediate. These data show that planting pattern of collard entries is relatively unimportant in the deployment of these sources of host plant resistance. The data also suggest that nonpreference is the primary mode of resistance to whiteflies for certain collard entries.

Effect of Ratooning on the Yield of Hybrid and Open-Pollinated Cabbage Cultivars

An experiment was done at Chiredzi Research Station, Zimbabwe, to establish the possibility of producing ratoon crops from four cabbage (Brassica oleraceae var capitata) cultivars: Sugarloaf (open-pollinated), Drumhead (open-pollinated), Goldern Acre (open-pollinated) and Exotic (F1 hybrid). There were significant differences in yield and head size between the cultivars in both the mother and ratoon crops. Exotic gave the highest yield in the mother crop (92.91 t/ha) while Drumhead produced the highest yield in the ratoon crop (35.94 t/ha). There were also differences in cultivar response to ratooning with relative head sizes for Drumhead, Golden Acre, Sugarloaf and Exotic being 79%, 74%, 46%, and 42% of the mother crop respectively. UNISWA Research Journal of Agriculture, Science and Technology Vol. 4 (2) 2000: pp 199-201

Dactuliophora Leaf Spot of Pearl Millet in Niger and Mali.

Pearl millet (Pennisetum glaucum (L.) R. Br.) fields and cultivar trials in Sadoré, Niger, and Samanko, Mali, were surveyed in late August 1999 Most plants were in the late stem elongation to panicle exertion stage Local open-pollinated cultivars, experimental hybrids, and inbreds had disease severities of up to 10% of foliage diseased, with most severe disease on lower leaves. Individual, young, brown necrotic lesions averaged 2 × 1 mm and were surrounded by circular to irregular purple watersoaked margins 1 to 7 mm wide. Lesions expanded in irregular concentric rings, with zones of necrosis often separated by zones of green tissue Mature, individual lesions averaged 4.3 × 1.9 cm. Entire leaves could be blighted by coalescing lesions. No sclerotia were observed in young lesions, but sclerotia consistently developed and were macroscopically visible in necrotic tissues of older lesions. Sclerotia were oblong to pyriform (averaging 178 × 124 mm) and borne on erumpent, cup-shaped sclerotiophores. When incubated under high humidity, sterile gray mycelia grew rapidly from necrotic lesions up to a distance of ≈5 mm on the lower leaf surface, which likely resulted in the large concentric zones necrosis. Fungal characteristics and symptoms were consistent with disease caused by Dactuliophora elongata Leakey (1,2). Based on observations at the International Pearl Millet Downy Mildew Virulence Nursery in Mali, it is likely that resistance to D. elongata exists. Leaf spot of pearl millet caused by D. elongata has been reported only in Nigeria (1,2). Our observations confirm that the pathogen also is present on pearl millet Niger and Mali.

日本産キャベツのバーティシリウム萎凋病抵抗性素材

Japanese cultivars of cabbage (Brassica oleracea L. var. capitata) were screened for their resistance to Verticillium wilt caused by Verticillium longisporum syn. V. dahliae Klebahn. No immune cultivar was found in a screening test of 51 F1 hybrids in a severely infected field, but some progenies of Kandama type (summer sowing type) such as 'Shutoku', 'YR Ranpo', 'YR Bibo', 'Kusabue 2', and Harukei type (fall sowing type) such as 'Kinkei 201' and 'YR 506' showed little or no symptoms. Thus, they possess enough resistance for commercial usage. Most Kandama type with resistance originated from crossing with the old Japanese cv. Kawasaki or Aichinatsumaki, some of the Harukei type with resistance originated from open-pollinated cultivars within the Nakanowase group. The susceptible cultivars of F1 hybrids which are derived from the Nakanowase and Copenhagen Market groups such as 'Natsuyama', 'Early Ball', 'Teruyoshi' and 'Reiho 1' characteristically masked the diseased symptoms on the leaf. When we inoculated 41 open-pollinated cultivars, some resistant cultivars were discovered in the Aichinatsumaki and Nakanowase groups. These results indicate that cultivars within Aichinatsumaki and Nakanowase groups possess resistance genes to this disease. By raising these progenies from these crosses, we have succeeded in isolating Verticillium wilt-resistant cabbages. Our data reveals that the resistance is controlled by dominant inheritance with some genes.

Evaluation of genotype, environment, and genotype-by-environment interaction for capsaicinoids in Capsicum annuum L.

The response, in terms of capsaicinoid content, of chile (Capsicum annuum L.) genotypes to different environments was studied. Double haploidlines, an F1 hybrid, and an open-pollinated cultivar estimated the genotype, environment, and genotype-by-environment interaction effect on the total capsaicinoids and on individual capsaicinoids. Significant differences were observed among the genotypes and among genotype-by-environment interactions over the environments. Among the genotypes in an environment, the within-genotype variances were also significantly different. The double haploid line, HDA 207, had low within-genotype variance for individual and total capsaicinoids, with the exception of the isomer of dihydrocapsaicin. Also for HDA 270, the genotype-by-environment interaction was negligible for individual and total capsaicinoids, Indicating stability across environments.

Genetic improvement of sunflower in Argentina between 1930 and 1995: II. Phenological development, growth and source–sink relationship

Historic sets of sunflower ( Helianthus annuus L.) cultivars released in Argentina between 1930 and 1995 were compared in two field experiments. Breeding and selection shortened cycle length: most of the reduction came from a reduction in time to anthesis, which together with a stable time from anthesis to maturity increased the proportion of the growing cycle given to grain growth. Shoot biomass at maturity was unrelated to year of cultivar release but a greater portion was produced after anthesis. The ratio between leaf area index duration from anthesis to maturity and grain number was taken as a measure of source-to-sink ratio; this ratio was smaller in hybrids than in open-pollinated cultivars. Variation in both the amount of oil per grain and grain mass were small in comparison with the variation in source-to-sink ratio indicating that additional carbon may have attenuated the effects of less leaf area duration per grain. Owing to the relative stability of the amount of oil per grain and the reduction in grain mass, the grain oil concentration increased despite the drop in source relative to sink. Further yield improvement will mostly depend upon the increase in the supply of substrates to fill the grain provided grain size is not restricted by events occurring before anthesis.

'Ramoso de Brasília': nova cultivar de couve-brócolos

Com o objetivo de desenvolver novas cultivares de couve-brócolos que pudessem servir como opção de plantio para os produtores, foi iniciado em 1984 um programa de melhoramento de couve-brócolos na Embrapa Hortaliças. Por meio desse programa, desenvolveu-se a cultivar de polinização aberta denominada 'Ramoso de Brasília', obtida após seis ciclos de seleção entre e dentro de linhagens desenvolvidas a partir das melhores plantas de uma população coletada em Itapecerica da Serra (SP). A cultivar Ramoso de Brasília é recomendada para cultivo de inverno, podendo também ser utilizada em verões amenos. É precoce e bastante produtiva. Apresenta grande número de ramificações laterais tenras e longas, cujo comprimento facilita a colheita. As inflorescências são verde-brilhantes, com ótimo aspecto comercial e excelente qualidade após cocção. Em plantios realizados em Brasília, tem-se observado menor ocorrência de podridão-mole nas inflorescências em campo e melhor conservação pós-colheita. Sementes da cultivar Ramoso de Brasília podem ser adquiridas no comércio em geral ou obtidas, em pequenas quantidades, na Embrapa Hortaliças.

003 Epidemiology and Control of Pepper Stip

Pepper stip is a physiological disorder manifested as gray-brown to greenish spots occurring on the fruit of bell, pimento, Anaheim, and other types of peppers, most noticeably on red fruit that mature under fall conditions. Most hybrid bell cultivars are resistant to the malady; the problem is most severe for pepper growers reliant on less-expensive, open-pollinated cultivars. In 1995, we initiated studies to evaluate the possible link between mineral nutrition and this disorder. Two susceptible open-pollinated cultivars and two resistant hybrid cultivars were grown in randomized plots at seven sites. Significant correlations were seen between the levels of potassium (r = 0.59) and calcium (r = -0.37) in whole leaves and the incidence of stip (P = 0.05). The stip-resistant cultivars also maintained less total nitrogen in the whole leaves than susceptible cultivars (P = 0.05). In 1996 and 1997, we undertook field studies to evaluate the effects of varying calcium and nitrogen application rates. Inconsistent results were observed with calcium applications. Moderate reductions in stip incidence was observed at some sites and no reduction at others following foliar calcium applications. Nitrogen nutrition had no effect on stip severity. In 1998, evaluation of a large number of open-pollinated cultivars was undertaken; `Gusto' showed excellent tolerance to pepper stip, followed by `Taurus' and `Cal Wonder 300'. We conclude that growers that are reliant on open-pollinated cultivars can utilize these cultivars to minimize the incidence of pepper stip.

Genetic improvement of sunflower in Argentina between 1930 and 1995. I. Yield and its components

Historic sets of sunflower cultivars released in Argentina between 1930 and 1995 were compared in two field experiments to identify contributions of breeding to the improvement of yield potential. Three yield components were considered: grain number; grain weight; and grain oil concentration. Both grain and oil yield were positively associated with year of cultivar release. There was a clear discontinuity in yield trends, however, with a marked step around 1970, when the first hybrids were released. No improvement in yield potential was apparent during long periods before and after this turning point. On average, hybrids outyielded open-pollinated cultivars by 23% for grain and 36% for oil. More grains that are slightly lighter and of greater oil concentration accounted for most of the variation in grain and oil yield between open-pollinated cultivars and hybrids. Increased grain number resulted from greater floret production, rather than enhanced floret fertility; variation in grain weight was associated with variation in rate rather than duration of grain filling. Further increase in yield potential could be achieved by maintenance of grain number ca. 7500 m −2 and increasing grain weight and oil concentration. The trade-off between grain weight and oil concentration deserves special attention. Targeting yield components in this way may accelerate the rate of improvement in grain and oil yield potential.

Background of U.S. Hybrid Corn

Understanding the history of a crop helps plant breeders select. This historical narrative discusses the background of hybrid corn (Zea mays L.) in the USA. It attempts to explain why certain open-pollinated cultivars persisted into today's hybrids. Domesticated corn originated by selecting larger, non-shattering ears in tropical, southern Mexico. Corn moved to temperate areas requiring adaptation to more variable, more stressful conditions. Flint corn arrived in the USA about 1000 BC and dent corn arrived after Columbus 2500 yr later. The first southern Corn Belt of the 1830s (Tennessee, Kentucky, and Virginia) moved northwest (Iowa, Illinois, and Missouri) by 1880; shorter-season, more drought tolerant cultivars were developed. About 1000 open-pollinated cultivars resulted from natural and artificial selection in flint × dent backgrounds. A few cultivars were widely adapted and became popular. Virtually all 1000 cultivars became parents of inbred lines. Yellow corn (containing vitamin A) proved better for feeding; white corn production diminished from 50% in 1920 to 1% of total in 1970. Earlier planting, higher plant densities, more nitrogen application, and wider adaptation affected hybrid selection. Pedigree background frequencies of 33 Pioneer Hi-Bred International Inc. proprietary, elite inbred lines directly estimate background Of >40% of U.S. hybrid corn hectarage and indirectly estimate the rest. Forms of ‘Reid Yellow Dent’(‘Iodent Reid’, ‘Troyer Reid’, ‘Osterland Reid’, ‘Stiff Stalk Synthetic’, Reid Yellow Dent per se, and ‘Funk Yellow Dent Reid’) are 50%. ‘Minnesota 13’ is 13%. ‘Northwestern-Dent’ is 5%. ‘Lancaster Sure Crop’ is 4%. ‘Learning Corn’ is 4%. These cultivars were widely adapted and popular. The results are consistent with evolutionary (adaptation) expectations. Genes for adaptedness to the temperate, U.S. Corn Belt (longer days, cooler minimum temperatures, and shorter, drier, more stressful seasons) were naturally and artificially selected; first, in widely adapted, open-pollinated cultivars then, in widely adapted hybrids. Old cultivar and inbred line background sources, few in number, indicate adaptedness is more important than diversity to increase yield.

Toward the Identification of Cytoplasmic Male Sterility in Leek: Evaluation of Organellar DNA Diversity among Cultivated Accessions of Allium ampeloprasum

Hybrid leek is more uniform and higher yielding than open-pollinated cultivars and is presently produced by asexual propagation of a genic male-sterile plant. A cheaper method to produce hybrid leek seed would be a system of cytoplasmic-genic male sterility (CMS). Restriction fragment length polymorphisms (RFLPs) in the organellar genomes have correlated with CMS in many crops. We undertook gel-blot analyses of the chloroplast and mitochondrial DNAs to assess cytoplasmic diversity among 62 accessions of the major cultivated forms of Allium ampeloprasum L. (leek, kurrat, and great-headed garlic). No polymorphisms were detected in the chloroplast genome of leek and kurrat. Three accessions of leek and one of kurrat possessed one or two of seven polymorphic mitochondrial probe-enzyme combinations. Great-headed garlic differed from leek and kurrat for six polymorphisms in the chloroplast genome and for many mitochondrial probe-enzyme combinations. Our analyses revealed few organellar polymorphisms among accessions of leek and kurrat, reducing the probability that selection of polymorphic cytoplasms will reveal CMS in leek.

Studies on performance of some open-pollinated maize cultivars in the Guinea savanna. III. Nitrogenuse efficiencies of four cultivars

Nitrogen use efficiency (NUE), defined as grain produced per unit of fertilizer nitrogen (N) applied, is a highly desirable agronomic character of non-leguminous crop varieties. This study was conducted to compare the NUEs of one local maize (Zea mays L.) variety and three improved composites released in Ghana since 1972, and determine the effects of breeding for improved agronomic performance on the NUEs of the improved cultivars. The four late-maturing maize cultivars (local, Composite 4,Dobidi, and Okomasa) were evaluated at 0, 80, and 160 kg N ha-1 and under three plant densities at Nyankpala and Damongo in 1992 and 1993. Across environment analysis for grain yield showed environment, plant density, nitrogen, and cultivar effects were significant (P Ghana Jnl.agric. Sci Vol.32(1), 1999: 19-26

Inbreeding and true seed in tetrasomic potato. I. Selfing and open pollination in Andean landraces (Solanum tuberosum Gp. Andigena)

True potato seed (TPS) may be an alternative method of potato production in developing countries. A breeding method for the sexual propagation of this vegetatively propagated crop should consider the development of parental lines and the type of cultivar to be released. Open-pollinated (OP) cultivars seem to be an inexpensive procedure to produce potato from true seed. However, OP progenies are the result of selfing and outcrossing in male-fertile tetraploid potatoes. The aim of the present research was to establish the effect of inbreeding and open pollination in TPS. Ten Andigena clones were used as parental material to derive hybrid (S0), inbred (S1 and S2), and open-pollinated (OP1 and OP2) generations. Significant differences among generations were found for pollen production, pollen viability (as determined by its stainability with aceto-carmine glycerol), number of flowers and berries plant-1, number of seeds berry-1, weight of 1000 seeds, and tuber yield plant-1. The parental populations were significantly different for most of the traits, but not for flower production and berry weight. The interaction of population ×generation was significant for pollen and seed production as well as for weight for 1000 seeds. All the traits evaluated except seed weight showed a strong inbreeding depression, while the OP progenies had intermediate values between the S0 and the S1. This demonstrates that open pollination in potatoes is not exclusively the product of selfing; it also results from outcrossing.