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A number of 10 base primers were screened to identify RAPD polymorphisms among a population of semi wild apricot genotypes that had been collected by Maxine Thompson in 1988. 30 families collected from trees at 6 locations were analyzed. DNA from leaf tissue of 180 plants, ca. 6 genotypes per family, were isolated and tested against 20 primers. Seven primers were identified that produced consistent results with relatively few (thus, scoreable) and consistent bands. DNA was isolated using the cTAB method and the effects of additional CsCl centrifugation isolation were tested. No differences were found. Reaction conditions were tested to ensure consistent results. Considerable RAPD polymorphism was observed in this population. Parsimony analysis is being conducted to assess the relative variation among and within populations and to determine whether collection location had a more significant effect on DNA variation than other factors such as outcrossing or level of heterogeneity within populations.

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The effect of irrigation with saline water on several citrus genotypes was evaluated in a short-term field experiment. Salinity levels ranged from 2.0 to 6.4 dS·m–1. Comparatively salt-tolerant Citrus species and Citrus × Poncirus hybrids were tested for their possible use as rootstocks for commercial citrus cultivars irrigated with brackish water. All the tested genotypes survived the highest salinities. At all salinity levels, the best chloride excluder was Cleopatra mandarin (Citrus reshni Hort. ex Tan.), and the worst was sour orange (C. aurantium L.). Gou Tou Cheng (C. aurantium hybrid?) and Rangpur (C. limonia Osb.) × Troyer citrange (C. sinensis L. × Poncirus trifoliata L.) RT803 were found to be promising genotypes for further evaluation as rootstocks tolerant to high salinities. Rangpur was unsuitable because of foot rot.

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The work reported here is an extension of studies reported in 1990. The general objective was to develop molecular markers for genotype `fingerprinting', with specific reference to possible clonal differences among `Pinot noir' clones. Leaf DNA from 8 cultivars and 9 `Pinot noir' clones were isolated. RFLP and RAPD markers were identified and used to characterize the genotypes. 65 32-P labelled cloned probes were constructed with the pUC18 plasmid and Hind-III digested `Pinot noir' DNA. The probes were tested for their ability to discriminate among the 8 cultivars. 3 probes pGAD10, pGAD15, and pGAD44 showed polymorphisms among the cultivars. pGAD15 was most useful, with 5 polymorphisms for the 8 cultivars. RAPD makers were also tested for `fingerprinting'. Several primers were tested and polymorphisms were identified among cultivars. However, significant problems with repeatability for some bands were observed. Therefore, a series of experiments were conducted to test the effect of season and extraction method. These factors did not account for the inconsistancy which seemed to be more a function of the primer used. None of these studies showed clear evidence that the `Pinot noir' clones tested were geetically different.

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Cut rose (Rosa hybrida L.) flowers placed in water often wilt prematurely, which is partially due to bacterial accumulation in the stems. Bacterial strains in the stems are mainly pseudomonads and enterobacteria. The possible sources of these organisms were investigated in `Sweet Promise' (trade name Sonia) roses. No bacteria were found in the xylem of intact plants. Cutting the stems with sterile secateurs introduced no bacteria at the cut surface or the stem interior, but cutting with nonsterile secateurs used by rose growers did. The secateurs sampled at rose growers contained Enterobacter agglomerans along with several other bacteria not found inside the xylem of cut flowers but did not contain pseudomonads. Although the plant surface may contain bacteria, freshly cut stems placed in water introduced no bacteria. Bacteria rapidly developed on the cut surface and inside the water-conducting elements when rose stems were placed in tap water, even when the stems had been surface-sterilized. However, there were no bacteria in vase water when the water and the stem surface had been sterilized. Since the stem and the secateurs are not a main source of bacteria inside stems and tap water contains pseudomonads and Enterobacter spp., we conclude that tap water is the main source of the bacteria inside cut rose stems.

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DNA from 9 cultivars and 5 `Pinot noir' clones were isolated with either the Delaporta or cTAB methods Twenty five 32P label led cloned probes were constructed with the pUC18 plasmid and Hind-III digested `Pinot noir' DNA. Standard methods of isolation and labelling were used. The probes were tested for efficacy of `fingerprinting' the 14 selections. rDNA and cloroplast a/h binding protein probes were also tested. The non-specific probes were not found to be useful as they bound to an excess number of sites and could not be removed from the southern blots, rendering them useless for further analysis. Grape specific probes bound at multiple sites, indicating that multiple fragments were incorporated into the plasmid vectors during library construction. With the greater variability observable with these multi locus probes, significant polymorphism was observed between cultivars, including `Cabernet sauvignon' and `Pinot noir' which were not distinguishable with GPI or PGM isozymes. Variability between clones of `Pinot noir' was observed with several probes, indicating that these selections are different. No variability had been observed at isozyme loci of the `Pinot noir' clones

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The objective of the experiments was to compare the performance of metal halide (MH) and high-pressure sodium (HPS) lamps on growth and yield of vegetables. Four experiments with lettuce were carried out. The lettuce grown under HPS lamps had a head firmness higher than under MH lamps. The difference between the type of lamps on fresh weight was not very constant with the period of production. There was no interaction between lamp and cultivar. Two experiments were carried out with tomato in Spring and Fall 1991. For a tomato crop, the yield and quality of the fruit were not affected by the type of lamps. Photosynthesis and transpiration of tomato and pepper plants were measured under MH and HPS lamps. No significant differences were found between both lamps under two humidity conditions and four PPFs. Under high humidity conditions, transpiration under MH was higher than under HPS.

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Several postharvest quality parameters of cantaloupe fruit were grown under different organic and mineral fertilization schemes We evaluated a Laguna hybrid (Asgrow) cantaloupe grown under a design of blocks completely randomized, with three fertilizer treatments corresponding to: T1, goat manure; T2, simple fertilization; T3 mixed fertilization, with six replications each. The fruits were mature-harvested and stored in a room with an average temperature of 18°C for posterior laboratory analysis. The results showed different effects of the treatments on the following parameters: total soluble solids, diameter of the fruits, and thickness of the pulp, and showed no effects on consistency of fruits, cavity, dry matter, and fresh weight. All these parameters decreased during the period of storage. The organic manure treatments showed the best values of most of the evaluated parameters.

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