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R. Nunez-Elisea, M. L. Caldeira, and T. L. Davenport

185 ORAL SESSION (Abstr. 723-730) FRUIT CROPS: GROWTH SUBSTANCES

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N.G. Beck, M.L. Arpaia, J.S. Reints Jr., and E.M. Lord

185 ORAL SESSION (Abstr. 723-730) FRUIT CROPS: GROWTH SUBSTANCES

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Edward F. Durner and Thomas J. Gianfagna

185 ORAL SESSION (Abstr. 723-730) FRUIT CROPS: GROWTH SUBSTANCES

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Fouad M. Basiouny

185 ORAL SESSION (Abstr. 723-730) FRUIT CROPS: GROWTH SUBSTANCES

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Thomas H. Boyle, Fabian D. Menalled, and Maureen C. O'Leary

The existence of self-incompatibility (SI) was demonstrated in `Britton' and `Rose' Easter cactus (Rhipsalidopsis). In a full diallel cross among five clones, 18 out of 20 outcrosses resulted in 68% to 100% fruit set, whereas reciprocal crosses between two of the clones and all five self-pollinations failed to set fruit. Pollen tube growth was greatly inhibited in styles of selfed pistils, but there was no evidence of pollen tube inhibition in compatibly crossed pistils. Easter cactus exhibited characteristics typically found in sporophytic SI systems (trinucleate pollen, papillate stigmas, and scant stigmatic exudate) together with those associated with gametophytic SI systems (stylar inhibition of pollen tube growth and absence of reciprocal differences in outcrosses). Additional experiments were performed to determine the effects of bud pollinations, growth regulators (BA, GA3, and NAAm), and high temperatures (0- to 48-h exposure at 40C) on the SI response. Heat treatments were more effective than either bud pollinations or growth regulators in overcoming SI, and yielded an average of 7.2 viable seeds per treated flower when plants were incubated for 12 h at 40C and selfed immediately after incubation. Isozyme analysis of the S0 parent and putative S1 progeny confirmed that selfing had occurred following heat treatments. Using S1 progeny in breeding programs may extend the flower color range and lead to a greater diversity in other plant characteristics than presently exists in cultivated germplasm. Chemical names used: N-(phenylmethyl)-1H-purin-6-amine [benzyladenine (BA)], gibberellic acid (GA3), and α-naphthaleneacetamide (NAAm).

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Renae E. Moran

The goal of this project was to evaluate the effectiveness of aminoethoxyvinylglycine (AVG) for increasing effectiveness of 1-methylcyclopropene (1-MCP) for maintaining firmness and preventing scald in `McIntosh' and `Cortland' apples (Malus ×domestica). AVG and 1-MCP used together maintained `McIntosh' apple firmness more than 1-MCP used alone after 120 or 200 days of controlled-atmosphere (CA) storage. AVG and 1-MCP can be used to maintain firmness of `McIntosh' when internal ethylene concentration (IEC) at harvest is as high as 240 μL·L-1, but CA storage life is limited to 4 months. AVG was not effective at increasing efficacy of 1-MCP on `Cortland' when IEC at harvest was not significantly different between AVG-treated and untreated fruit and IEC was less than 2 μL·L-1. AVG increased efficacy of 1-MCP on `Cortland' when IEC was 36 μL·L-1 in untreated fruit compared to undetectable in AVG treated fruit. 1-MCP prevented scald of `Cortland' in 1 year and reduced it to 5% or less in another year when fruit were stored 120 days. 1-MCP reduced `Cortland' scald to 34% or less after 200 days of storage.

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Yong Yang, Xueyong Liu, Yuanli Jiang, Zuoxiang Xiang, Qingguo Xu, Na Zhao, and Bichao Shu

adjustments to adapt/tolerate salinity stress, which include the changes of free amino acids and carbohydrates metabolism. Free amino acids are fundamental compositions in the processes of protein and other growth substances synthesis, which are vital for

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M.H. Aboul-Nasr and M.A. Ahmed

This experiment was performed at the Tissue Culture Laboratory of the Horticulture Dept. of the Faculty of Agriculture at Assiut Univ., Egypt. After several attempts to determine the proper stage of buds for collection of pollen, we determined that the tetrad stage was most suitable. The pollen was cultured on either MS or B5 liquid or solid media (7% agar). Both media were used as basic salts or supplemented with growth regulators. The four growth substances were BA, NAA, K, and 2,4-D. Each growth substance was added to the medium separately as follow: BA, NAA at 15, 10, or 5 ppm; K at 0.1, 1, 2, or 5 ppm; and 2,4-D at 0.5, 1, or 5 ppm. The solidified medium was superior to the liquid medium at all the treatments that were used for callus formation. Using B5 medium did not result in any callus. The highest value of callus formation was obtained when MS medium supplemented with BA at 5 ppm. Moreover, the callus that was grown on the MS medium that had BA at 5 or 10 ppm developed a merstim tip. The control treatment produced calluses but did not develop any meristem tips. This process can be used to develop haploid plants.

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Rodomiro Ortiz and Dirk R. Vuylsteke

Apical dominance, i.e., the inhibition of lateral bud growth due to growth substances released by the terminal bud, has been considered as a limiting factor for the perennial productivity of plantains (Musa spp., AAB group). Segregation ratios in F1 and F2 plantain-banana hybrids suggest that inheritance of apical dominance is controlled by a major recessive gene, ad. The dominant Ad allele improved the suckering of plantain-banana hybrids, as measured by the height of the tallest sucker at flowering and harvest. At harvest, the ratoon crop of the diploid and tetraploid hybrids had completed 70% to 100% of its vegetative development, whereas the ratoon of the plantain parents, due to high apical dominance, was only at 50% of total pseudostem growth. Sucker growth rates are generally the result of gibberellic acid (GA3) levels, and it is suggested that the Ad gene regulates GA3 production. However, the Ad gene has incomplete penetrance, genetic specificity, and variable expressivity. Increased frequency of the Ad gene and a commensurate improvement in the suckering behavior of the diploid populations may be achieved by phenotypic recurrent selection.

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Gerson R. de L. Fortes, Nilvane T.G. Müller, Janine T.C. Faria, Luciana B. Andrade, and Marisa de F. Oliveira

Asparagus is a vegetable that presents an increase in yield when propagated by meristem culture. On the order hand, the rooting phase in asparagus is greatly affected by the previous phase, i.e,. multiplication. This species presents a better rooting performance when callus is formed at the shoot base. So, the aim of this work was to evaluate treatments during the multiplication phase, which also leads to callus formation at the shoot base. The initial explants came from shoots being cultivated in vitro. It was tested kinetin at: (0.0, 0.5, 1.0, 1.5, and 2.0) μM; ancymidol at (0.0 and 0.5) μM and NAA at (0.0 and 0.5) μM for both genotypes, which were cultured in a MS medium added to sucrose (30 g·L–1), agar (6.0 g·L–1) and myo-inositol (100.0 m g·L–1). Shoots bearing two buds were inoculated in 10-ml test tubes and placed in a growth room for 30 days when they were evaluated. The addition of kinetin significantly improved the number of buds and at 1.3 μM this growth substance presented the best results as number of shoots is concerned. NAA application promoted a negative effect on spear bearing. The addition of ancymidol in this phase did not improve the bud multiplication. It was shown that clone M14 performed better than the hybrid cv. Deco as multiplication is concerned.