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Composting is considered an environmentally sound and economically viable alternative for the management of organic residues. Although compost product may be used as a peat substitute in soilless culture, it generally has poor physical structure, low nutrient content, high pH, and high salt content. This study chose the coir fiber (CF) produced from coconut (Cocos nucifera) and bamboo vinegar (BV) produced from mottled bamboo (Phyllostachys bambusoides) as the media amendments, and evaluated the effects of CF (at 0%, 15%, and 25%) and/or BV (at 0%, 0.5%, and 1.0%) on the physical, chemical, and microbiological properties of composted green waste (CGW) and on the growth of peacock arrowroot (Calathea makoyana). The highest quality growing medium and the best growth of peacock arrowroot were obtained when CGW was amended with the combination of 15% CF and 0.5% BV; the lowest quality medium and the least plant growth were obtained with nonamended CGW. The optimal combination not only improved particle-size distribution and adjusted bulk density (BD), porosity, and water-holding capacity (WHC) into ideal ranges, but it also decreased pH and electrical conductivity (EC) and increased microbial numbers, enzyme activities, and macro- and micronutrient contents in the CGW. Relative to the nonamended CGW, the optimal CGW reduced the BD from 0.58 g·cm−3 to 0.34 g·cm−3 and the pH from 8.05 to 5.61, and increased the total porosity (TPS) from 48.1% to 77.0% and the WHC from 57.4% to 75.5%; the optimal CGW increased shoot fresh weight, shoot dry weight, root fresh weight, root dry weight, plant height, crown breadth, number of leaves, and total root length by 83.9%, 77.8%, 66.1%, 65.1%, 63.6%, 73.8%, 55.6%, and 65.2%, respectively.
The grape belongs to the genus Vitis L., which are divided into two subgenera, Euvitis Planch. and Muscadinia Planch. The Euvitis has 50 to 70 species, in which V. vinifera L. is a predominant species with hundreds of known commercial cultivars grown world wide. The Muscadinia (muscadine grapes) consists of only two to three species predominated by V. rotundifolia and only commercially cultivated in the southeastern United States. V. rotundifolia is known by its multiple resistance to almost all grape diseases and insects found on the Euvitis species, while the latter possesses good fruit characteristics that do not exist in muscadines. Attempts to produce rotundifolia-vinifera hybrids to combine good fruit quality and disease resistance of both into F1 hybrids have been made by grape breeders for many years. Limited success was reported when the V. vinifera was used as seed parents. This research extended the interspecific crosses beyond V. vinifera into other Euvitis species. Among the Euvitis species, A. aestivalis, V. cinerea, V. champinii, V. labrusca, V. monticola, V. nesbittiana, V. riparia, V. rupestris, V. thunbergii, V. quinguangularis, all with pistillate flowers, were used as female parents pollinated with V. rotundifolia pollen. Eight out of the 10 cross combinations except V. cinerea and V. thunbergii set fruits. However, most of the Euvitis-rotundifolia crosses had extremely low fruits set (<1% of pollinated flowers). The only exception was V. labrusca cv. Woodruff, which had very high percentage of fruit set (70%). Interestingly, the fruits of V. labrusca cv. Woodruff × rotundifolia were pathonocarpic that had only half size of regular fruits set from open pollination with pollen sources from other Euvitis species. In the reciprocal crosses, three pistillate V. rotundifolia cultivars, `Fry', `Higgins', `Jumbo', were used as female pollinated by pollen from Euvitis species. Limited fruit sets were found from the crosses of V. rotundifolia × V. shuttleworthii, V. cordifolia, V. rupestris, V. Piasezkii, V. quinquagularis. Results from this study indicated that hybridization between Euvitis and muscadinia species is indeed very difficult but it is possible, and some Euvitis species are cross more compatible with V. rotundifolia than the others.
Vitis rotundifolia (Muscadine grapes), a native species characterized with multiple resistance to grape diseases and insects, are cultivated throughout the southeastern U.S. for fresh fruit and processing. However, the species falls short of consumer's expectation as fresh fruit due to its seediness and thick skin. However, Vitis vinifera, a predominant Vitis species grown worldwide possesses good fruit characteristics such as seedlessness and edible skin but is susceptible to many diseases. Attempts to produce rotundifolia-vinifera hybrids to combine good fruit quality and disease resistance of both into F1 hybrids have been made by grape breeders for many years. Limited success was only reported when the V. vinifera was used as seed parents. Pollinating seedless vinifera pollen onV. rotundifolia stigma was made in 1993 and 1994. More than 20,000 flowers from 34 cross combinations were pollinated. These crosses were made to see if there is any chance to produce hybrids when muscadine grapes were used as female parent and specifically to introgress the seedlessness from European grapes into muscadine grapes. A few hundred seeds were collected from these crosses and germinated in a greenhouse. Two seedlings were clearly distinguished from the others with morphology intermediate between muscadine and the vinifera grapes, while the rest looked straight muscadine grapes derived from possible contaminated pollination. This conclusion was further confirmed by isozyme and DNA markers. One of the seedlings produced from the cross of `Jumbo' × `Thompson Seedless' grew vigorously and has been setting fruit since 1996. Fruit are mixture of stenospermocarpic and pathonocarpic seedlessness. Fruit setting and pollen viability test indicated that this hybrid is at least partly self-fertile. Many other characteristics of the hybrid, such as leaves, stems, tendrils, time of budbreak, bloom date, and ripen date are intermediate between muscadine and bunch grapes. The hybrid is resistant to Pierce's disease, anthracnose disease, and downy mildew, which are the limited factor to growing V. vinifera in the hot and humid southeastern U.S. This is the first report of a seedless hybrid from V. rotundifolia × V. vinifera.
Non-native grape species such as V. vinifera and V. labrusca can not sustain the hot and humid environment of Florida due to their susceptibility to various diseases. Vitis rotundifolia (muscadine grapes) is native to Florida and the southeastern United States and adapted well to this climate condition. They are highly resistant to almost all grape foliage diseases and root pests such as nematode and phylloxera. Theoretically, muscadine grapes may become a valuable rootstock for bunch grapes. Unfortunately, most previous studies found that muscadine grapes were graft-incompatible with bunch grapes by normal grafting techniques. This study was to look for an alternative technique to graft V. vinifera onto muscadine rootstocks. A preliminary study indicated that bunch grape scions were successfully grafted on adult muscadine grapes. Two V. vinifera grape cultivars, `Thompson Seedless' and `Chardonnay', and two muscadine grape cultivars, `Carlos' and `Alachua', were used for this study. The muscadine grapes used as rootstocks are 6-year old field-grown vines and V. vinifera was used as scions. Using the common V-type grafting method was completely failed in more than 150 attempts. We then tried to insert the first-year buds of V. vinifera into 1- to 3-year-old muscadine canes. Surprisingly, the survival rate of the inserting buds was moderately high when `Carlos' was used as the rootstock. `Thompson Seedless'/`Carlos', `Chardonnay'/`Carlos' reached 53% and 33%, respectively. Successful grafting but lower survival rate was also obtained when `Alachua' was used as the rootstock (10% in `Thompson Seedless/`Alachua' and 3% in `Chardonny'/`Alachua'). The average survival rate of `Thompson Seedless' on the muscadine rootstocks was 36%, and `Chardonnay' was 12%. Regardless the cultivar of the scions, buds survived on `Carlos' and `Alachua' rootstocks were 44% and 5%, respectively. Results from this study indicated that V. vinifera grapes could be successfully grafted onto muscadine rootstocks. The survival rate varied depending on cultivars used for both scion and rootstock. It would be very interesting to see if resistance to certain diseases such as the Pierce's disease can be improved in those V. vinifera grape with muscadine roots and trunks derived from this preliminary study.
Bacterial leaf spot of lettuce, caused by Xanthomonas campestris pv. vitians, is a devastating disease of lettuce worldwide. Because there are no chemicals available for effective control of the disease, host-plant resistance is highly desirable to protect lettuce production. A new method for fast screening and accurate identification of bacterial leaf spot (BLS)-resistant lettuce has been developed in our laboratory. A total of 79 lettuce genotypes (69 germplasm lines and 10 adapted cultivars) were evaluated with this technique for response to X. c. vitians. Disease incidences ranged from 92% to 100% and disease severities were between 1.6 and 3.6 on the 0 to 4 scale. No highly resistant genotypes were identified. However, 12 genotypes did not significantly differ for disease severities from the moderately resistant ‘Little Gem’ lettuce that was used as a resistant control. Comparison of disease severities of 10 commercial cultivars and three moderately resistant germplasm lines tested at the seedling stage and adult stage showed a high positive correlation (r = 0.87, P < 0.0001) between tests. The new screening method should be useful in breeding programs, in which great numbers of plants need to be tested during germplasm evaluation, and for single plant selection as well as other studies. The identification of new sources of moderate resistance in this study could facilitate development of cultivars with a higher level of resistance through the gene pyramiding approach.
During the winter of 1991-92. four cultivars of Alstroemeria: `F-180'. `l-5'. `Parigo Pink' and `Parigo Red' were treated with eight different overwintering covers: straw, straw with plastic covering, sawdust, sawdust with plastic covering, hoops with plastic covering, hoops with microfoam covering, microfoam and a control with no cover. All covers had significant effects on the survival of `Parigo Pink' and `Parigo Red'; mulching with straw only gave the best winter protection. There were also significant genotypic differences among the four cultivars: 73% of `Parigo Pink' and `Parigo Red' plants survived after winter, but none of `F-180' or `l-5' survived. In addition, pre-winter evaluation indicated that there were significant genotypic differences among the four cultivars with cold resistance. The cold resistance was highly correlated with winter hardiness. It was concluded that: (1) pre-winter evaluation could be an efficient indicator for winter hardiness selection on Alstroemeria and (2) application of straw provided sufficient winter protection for zone 6 Alstroemeria. Other approaches of mulching need to be further identified in order to protect all Alstroemeria for overwintering in the northeastern United States.
An interspecific hybrid of Alstroemeria aurea × Alstroemeria caryophyllaea was rescued by immature ovule culture and was completely sterile. To restore the fertility of the hybrid, young, vigorous shoots and buds were treated aseptically with three colchicine levels (0.2, 0.4, and 0.6% in DMSO solution) at four treatment durations (6, 12, 18, and 24 hours), before being cultured onto a shoot regeneration medium for regrowth and development. The growth and development of all treated shoots were retarded by the colchicine. New shoots were regenerated from 61% of the surviving cultures after one month. The degree of recovery was not significantly different among treatments, although the highest concentration (0.6%) and the longest time treatment (24 hours) resulted in some morphological abnormalities. Cultures with newly regenerated shoots/buds were able to initiate roots and, eventually, sixty plantlets were transplanted into the greenhouse after acclimatization. Cytological examination of the root tip cells of the plantlets indicated that tetraploids (2n=4x=32) as well as aneuploids plants were generated from the colchicine treatment, whereas all plants from the control were diploids (2n=2x=16). Details explaining cytological changes and the fertility of the colchiploids will be presented.
Gibberellic acid, a plant growth regulator commonly sprayed for seedless bunch grape cultivars, was used to spray on the seeded muscadine grape cultivars `Carlos', `Fry', `Higgins' and `Triumph'. GA3 at 100 to 300 ppm were sprayed on leaves and fruit clusters before and after anthesis. The flower/fruit clusters also were dipped into a much higher concentration (1000 ppm) in addition to the sprayed concentration of GA3. Berry weight significantly increased in all the sprayed vines, with a maximal increase up to 50%. Early and more uniform ripening was observed in the cultivar `Triumph'. More than 20% of seedless berries also were found on the GA3-sprayed `Triumph' vines. However, the latter two responses (early ripening and seedlessness) did not occur in other cultivars tested. Similar results also were obtained in the dipping treatments. The results indicated that the seeded muscadine grapes responded well to the GA3 treatments in general, but genotype variation is obvious.
Fluorescence microscopy was used to examine the unilateral intersubgeneric incongruity of muscadine grape (Muscadinia Planch.) × bunch grape (Euvitis Planch.). Pollen grains of bunch grape hydrated and germinated on the stigmas of muscadine grape. Healthy pollen tubes of the bunch grape also penetrated the stigma and entered into the style without obstacles. However, most bunch grape pollen tubes were arrested in the style near the stigma, and few bunch grape pollen tubes were found at the base of the style. Barriers to the intersubgeneric crosses apparently occurred before fertilization; abortion of pollen tubes in the style was the major cause of failure for the cross of V. rotundifolia Michx. × Euvitis.