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Joan Tous, Agustí Romero, Juan F. Hermoso, Antònia Ninot, Joan Plana and Ignasi Batlle

composition ( Binder et al., 1959 ; Caja et al., 1988 ; Davies et al., 1971 ; Marakis et al., 1988 ; Vardar et al., 1980 ), but there is very little information on the agronomical performance of carob cultivars ( Tous and Batlle, 1990 ), which is why there

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T.E. Dickert and W.F. Tracy

Heterosis in corn (Zea mays L.) usually results in earlier flowering, larger plants, and increased yield. In extremely early sweet corn the effect of heterosis on flowering time may be reduced or eliminated due to developmental and physiological requirements for vegetative growth before the transition to reproductive phase. The objective of this study was to determine the level of heterosis and the combining ability for flowering time and other agronomic traits in a diallel cross of six very early open-pollinated sweet corn cultivars. The diallel was grown in 1995 and 1996. Hybrids and parents averaged over hybrids differed for silk date, plant height, ear height, 10-ear weight, ear length, and 100-kernel weight but did not differ for row number and ear width. Heterosis for silk date was significant, but the difference between parents and hybrids was very small, 0.5 day. No hybrids were earlier than the earliest parent, and average midparent heterosis was -0.8%. In contrast midparent heterosis was significant and relatively high for 100-kernel weight (10.0%), ear length (12.9%), ear height (8.6%), plant height (9.0%), and 10-ear weight (28.2%). The traits with low heterosis had very high general combining ability/specific combining ability ratios while these ratios were much smaller in traits with high heterosis. Heterosis for many of the traits, including 10-ear weight, was higher than published values. Conversely, heterosis for flowering time was small, compared to other traits in this study and to published values for silk date, indicating that this extremely early germplasm may be at or near the limit for flowering time under the photoperiod and temperatures typical of summer in Madison, Wis. (43.05°N, 89.31°W).

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Hagai Yasuor, Alon Ben-Gal, Uri Yermiyahu, Elie Beit-Yannai and Shabtai Cohen

(kg·ha −1 ). Agronomic NUE (ANUE); Y f /N app , where Y f is marketable fruit yield (Mg·ha −1 ), N app is seasonal applied N (kg·ha −1 ). Biomass NUE (BNUE); Y bm /N app , where Y bm is total dry biomass production (kg dry wt/ha), N app is

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Francisco M. del Amor and María D. Gómez-López

the type of substrate ( Table 3 ), the differences for each substrate being of little relevance from an agronomical point of view. Table 3. Fruit quality parameters of sweet pepper in the three growth years (2005, 2006, and 2007) and the three

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Gilles Saindon, Henry C. Huang and Gerry C. Kozub

The putative yield advantage associated with growing upright beans (Phaseohs vulgaris L.) at high planting densities in narrow (0.23-m) rows might he compromised by a higher risk of white mold [Sclerotinia sclerotiorum (Lib.) de Bary] because of reduced air flow through the crop canopy. This four-yeai-study was undertaken to compare the white-mold avoidance and agronomic attributes of upright bean lines and to determine whether their yields can he increased by raising planting density. Four upright lines and a viny line as a control were established in narrow rows at planting densities ranging from 25 to 60 plants/m* in a field artificially infested with sclerotia of S. sclerotiorum. On average, the four upright lines had lower incidence of white mold and smaller disease severity indices than the control, `UI36', indicating that the development of white mold is reduced in dense, erect canopies. There were differences in disease response among the upright lines, with `ISB82865' and `UI906' being the least and most susceptible entries, respectively. Increases in planting densities resulted in higher yields and influenced the development of white mold hut had no effect on vine length, lodging, and maturity. However, the planting density effect on the disease response was not consistent among entries in 2 of the 4 years. The results of this study indicate that upright beans can he grown at high planting densities without greatly increasing the risk of a white-mold outbreak. The choice of the most appropriate planting density for upright beans depends largely on the cost of seed.

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Eddo Rugini, Cristian Silvestri, Marilena Ceccarelli, Rosario Muleo and Valerio Cristofori

plants from Ascolana Tenera and Moraiolo cultivars. These mutants showed low agronomic value ( Donini and Roselli, 1972 ) and cytogenetic instability. Subsequently, some mutants with compact phenotype from cultivars Leccino and Frantoio irradiated

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Jaume Lordan, Anna Wallis, Poliana Francescatto and Terence L. Robinson

they were each kept simple by removing sublateral branches to create a single axis for each branch. Agronomic assessments. Yield (kg) and fruit number were recorded annually from each tree, and fruit size was then calculated using measured data ( Marini

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Lorenzo León, Luis M. Martín and Luis Rallo

Thirteen characters were evaluated over four years in progenies from a diallel cross among the olive (Olea europaea L.) cultivars `Arbequina', `Frantoio', and `Picual' to determine if phenotypic correlations existed between these characters. Yield per tree, ripening date, oil yield components and fatty acid composition were recorded annually once seedlings began to flower and produce fruit. Significant correlations were found between several characters including oil yield components and fatty acids composition. Lower correlation coefficients were obtained between ripening date and oil and oleic acid content. Generally, yield was not correlated with the other characters evaluated. Principal components analysis confirmed the main correlations among characters and showed them to be independent of the parents used.

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Fredy R. Romero, Kathleen Delate and David Hannapel

Consumption of Echinacea, one of the most popular botanical supplements, continues to expand in the United States. In addition, organic herbal products have captured a large share of the botanical supplement market. We evaluated commercial organic production of the three most-important medicinal species of Echinacea, E. angustifolia DC, E. purpurea (L) Moench., and E. pallida (Nutt.) from two seed sources. Plants were grown in the field for 3 consecutive years. We found that, during the first year, screen cages were associated with enhanced post-transplanting establishment. Growth of E. angustifolia was not affected by either production system or seed source after 3 years, and yields were equivalent for years 2 and 3 for this species. Growth of E. purpurea was affected by production system, but not by seed source, during the first 2 years. In year 3, neither seed source nor production system affected growth of E. purpurea. Yield of E. pallida was greater in the open field the first year; no difference between production systems was found during the second; and, by the third year, plants growing in screened cages produced more than plants growing in the open field. Production system affected yield of E. purpurea only during year 2, and yield was greater in the open field than in screened cages. Echinacea plants in the open field, however, were more affected by aster yellows disease, with an infection rate of 17% for E. purpurea in the open field compared to 3% under screen cages. Based on these results, in areas of aster yellows incidence, excellent Echinacea root yields can be obtained under screen cages using organic seeds.

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Mark Gaskell

Organic vegetable production acreage is expanding in California, but little research-based information is available to guide growers. Several new organic fertilizer materials are available but little data exists on efficient use of these materials. During 1998, the following materials: compost (C), pelleted chicken manure (PCM), fish meal (FM), liquid fish (LF), liquid soybean meal (LSM), feather meal (FTM), and seabird guano (SG) were evaluated. Each material was applied at treatment rates of 0, 60, 120, and 180 kg nitrogen (N)/ha to transplanted, sprinkler irrigated bell peppers. The materials were applied as 30N pre-transplant (PRE) and 30N at 20 days post-transplant (POST) for the 60N treatment; 60N PRE and 30N at 20 days POST and 30N at 40 days POST for the 120N treatment; and 60N PRE, 30N at 20 days POST, 45N at 40 days POST, and 45N at 70 days POST for the 180N treatment. Weekly soil nitrate nitrogen (SSN) over 16 weeks POST and fresh pepper yield was determined for all treatments. Weekly SSN varied from lows of 4 mg·kg-1 in 0N-treated plots to over 80 mg·kg-1 in FTM 180N-treated plots. Highest SSN was observed in FTM-, SG-, LSM-, LF-, and FM-treated plots at 180N and peaks in SSN lagged fertilizer application 3 to 4 weeks. Total pepper yield was not as markedly affected as early yield and size. Highest early yield and largest sizes were observed in FTM 180N-treated plots. Compost treated plots at 180N produced highest economic return per fertilizer dollar.