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J. Lu, Z. Liu, and Y. Zheng

Genetic relationships among 42 grape accession of at least 15 species were estimated and compared using RAPD and isozyme techniques. These accessions were either hybrids or wild collections of the Asiatic species, the American species, the European grape (V. vinifera), and muscadine grape (V. rotundifolia). A total of 196 RAPD fragments were generated from twenty 10-mer primers. The pairwise similarities among the accession ranged from 0.46 to 0.94. A dendrogram was generated based on the RAPD similarity coefficients. Species/accessions were basically grouped together in accordance with their geographic origins. The similarities and dendrogram resulted from the RAPD analysis were consistent with the ones generated from the isozyme data, and also consistent with the known taxonomic information. This result suggest that the RAPD method, like isozyme, is an useful tool for studying grape genetic relationship/diversity and origination.

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Y. Wang, Y. Liu, P. He, O. Lamikanra, and J. Lu

Resistance to grape anthracnose [Elsinoë ampelina (de Bary) Shear] was evaluated in 13 known Vitis species and five taxonomically undescribed grapes native to China. One hundred and eight clones of Chinese Vitis species were tested under field conditions between 1990 and 1992. Berry infection did not occur in these species. Leaves displayed strong resistance to anthracnose, although intraspecific variations were observed. There was no relationship between anthracnose resistance and geographical origin of the species. Results from this study indicate that oriental grape species are useful for disease-resistance breeding.

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J. Lu, O. Lamikanra, Y. Wang, Z. Liu, and D. Ramming

The grape is an important horticultural crop that is grown worldwide. Breeding a new grape cultivar by conventional means normally will take several generations of backcross, at least 15 years. The efficiency and speed of selection can be accelerated if genetic markers are available for early screening. This project is designed to generate RAPD markers linked to viticulturally important traits, including seedlessness and pistillate genes. A F1 population with 64 progenies of V. vinifera was used for the RAPD analysis. Bulked Segregant Analysis (BSA) method was used for RAPD primer screening. Three-hundred primers were screened between the two pairs of pooled DNA samples, seeded and seedlessness, pistillate and perfect flowers. At least 10 primers produced one polymorphism each between the pools. Further analysis revealed that one of these RAPDs cosegregated tightly with the seedlessness trait, while the others either had loose linkage or no linkage to the traits. To make the RAPD marker useful for breeding selection, an attempt was made to convert it into SCAR marker. The results demonstrated that the RAPD marker may be useful for grape breeding and interpreting inheritance of a particular trait in grapes.

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C. Stevens, V. A. Khan, J. Y. Lu, A. Y. Tang, and A. E. Hiltbold

Partial steam and chemical sterilization of soil rich in organic matter increased the soil nutrients, little information exists with regard to the effect of soil solarization (SS) in this regard. A study was established to determine the effects of SS in combination with wheat residue and subsequent crop residue on increased growth response (IGR) of cole crops and soil fertility for two years. SS for 90 days increased K+, P, Ca++ and Mg++ 3 times more within five months after SS. The SS effect released higher levels of total N in the soil. However, increase levels of N was lower than that required for maximum IGR of collard. The IGR of cole crops without fertilizers was higher in SS plots as compared to bare soil. The IGR of collard was evident almost two years after SS.

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C. Stevens, V. A. Khan, J. Y. Lu, M. A. Wilson, Z. Haung, and J. E. Brown

In 1988 and 1989 a muscadine vineyard at Tuskegeee, Alabama was treated by post plant soil solarization (PSS) (covering of moist soil around 'Carlos' muscadine plants (Vitis rotundifolia Michx.) with clear polyethylene plastic mulch to achieve high soil temperature for 30 and 75 days, respectively during PSS. Grape plants grown in solarized soils showed increases in growth response such as increased yield. Foliage of grape plants was evaluated for reaction to black rot incited by Guignardia bidwellii. A significant reduction of the foliage disease black rot was observed. The number of lesions per leaf, lesion size and percent leaves with lesions were significantly reduced by as much as 56% up to three years after solarization.

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V. A. Khan, C. Stevens, J. Y. LU, M. K. Kabwe, and Z. Haung

Clear (CM), and black plastic (BM) mulches and bare (BS) soil plus VisPore (V) row cover (VCM, VBM, VBS), CM, BM, and BS in combination with drip irrigation and three planting dates January 3rd, February 16th, and March 16th, 1990, were used to evaluate the yield of `Georgia' collard greens. At the 1st planting date, both mulches and row cover treatments had significantly higher yield. At the 2nd and 3rd planting dates there were significant interactions between mulch and row cover. The interaction at the the 2nd planting date showed that yield was highest with VCM and VBS treatments and at the 3rd planting date CM, BM and VBS increased yield, respectively. The number of days to harvest decreased with each planting date and bolting was not observed for any planting date or treatment combination.

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V. A. Khan, C. Stevens, J. Y. Lu, M. Kabwe, and Z. Haung

Clear (CM) and black (BM) plastic mulch and bare soil (BS) plus VisPore (V) row cover (VCM, VBM, VBS), BM, CM and BS in combination with drip irrigation were used to evaluate the growth response of these treatment combinations on 5 and 9 wks old `Clemson Spineless' okra transplants grown in sandy loam soil. Mulched treatments significantly increased the survival rate of 5 wks old transplants while VCM and VBM treatments increased significantly the number of vegetative branches of 5 wks over 9 wks old transplants. Total and marketable yield, as well as total and marketable number of pods were significantly influenced by mulched treatments rather than by the age of transplants.

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D. G. Mortley, J. Y. Lu, P. Grant, and G. W. Carver

The effect of periodic removal of peanut foliage for use as a green vegetable on final foliage and nut production was evaluated in a field experiment in the summer of 1992. Georgia Red peanut cultivar was grown in Norfolk sandy loam soil in a randomized complete block design with four replications. Treatments consisted of removing peanut foliage at 2, 4, and 6 weeks, starting six weeks after planting, and an untreated check. Fresh foliage yield declined an average of 30% while dry weight declined 34% when harvested at 2 and 4 weeks. Nut yield declined 33% when harvested at 2 and 4 weeks but yield decreased only 10% when harvested at 6 weeks. Peanut greens are highly nutritious especially as a rich source of vitamin C and protein. For good balance between foliage and nut production, it appears that harvest intervals should be after four weeks.

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M.A. Sherif, P.A. Loretan, A.A. Trotman, J.Y. Lu, and L.C. Garner

Nutrient technique (NFT) and deep water culture (DWC) hydroponic systems were used to grow sweetpotao to study the effect of four nutrient solution treatments on: translocation of nutrients and plant and microbial population growth in split-root channels. 'TU-155'cuttings (15 cm) were prerooted for 30 days in sand in 4 cm CPVC pipes 46 cm in length. A modified half Hoagland (MHH) solution was supplied ad libidum. After 30 days, plants were removed and the roots of each plant were cleaned and split evenly between two channels (15 cm deep by 15 cm wide by 1.2 m long). four plants per channel. Nutrient solution treatments (replicated) were: MHH-MHH: MHH-Air, MHH-deionized water (DIW); and monovalent (Mono) - divalent (Dival) anions and cations. Solution samples were continuously collected at 7-day intervals for microbial population profiling. Plants were harvested after growing for 120 days in a greenhouse. Storage roots, when produced, were similar in nutritive components. However, no storage roots were produced in Air or Mono channels and only a few in DIW. Fresh and dry weights for storage roots and foliage were highest in MHH-MHH in both NFT and DWC in repeated experiments. Population counts indicated that nutrient solution composition influenced the size of the microbial population in NFT. Population counts were highest in Dival channels. The microbial population counts (4.20-7.49 cfu/mL) were. relatively high in both NFT and DWC systems.

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C. Stevens, V. A. Khan, M.A. Wilson, D. J. Collins, J. E. Brown, and J. Y. Lu

Agriplastic black mulch (BM), row cover (spunbonded) plus black mulch (RBM) and solarized soil treatments plus black mulch (SBM). row cover plus black mulch on solarized soil (RSBM) and row cover plus solar&d soil (RSBS) increased Floradade tomato yield from 56 to 285%. number of tomatoes and plant height compared to the non-solarized bare soil (BS). When comparing increased growth response (IGR) of the plants grown in the solarized soil with no row cover agriplastic treatments, there was no significant differences among them. When comparing the IGR parameters of tomato plants grown under SBS, BM, and RBS there were no significant differences among them. Spunbonded row cover treatments increased IGR of tomatoes over all treatments without row cover. A significant increase in plant growth promoting rhizobacteria (PGPR) was observed in the rhizosphere soil of Floradade tomatoes grown in solarized soil alone and in those other agriplastic treatments compared to bare soil. There appear to be no differences in PGPR population among SBS and all agriplastic treatments.