1,720,986 research outputs found
Fluctuations of endogenous Gibberellin A4 and A7 Content in apple fruits with different sensitivity to Russet
No full textSkin russet of 'Golden Delicious' apples (Malus domestica Borkh.) is the result of an interaction between an epidermal structure, more or less sensitive to the disorder, which is the predisposing cause, and external environmental factors, such as high relative humidity, rain, low temperature, or some pesticide treatments. However, treatments with GA4 or GA 4+7 in the first period of fruit development reduce russeting. Trees of four 'Golden Delicious' clones ('Clone B', 'Smoothee', 'Crielaard', and 'Reinders') with different sensitivity to russeting were covered, in order to protect the fruitlets from russeting factors, for 1 week in weeks 2 to 8 after full bloom, or for the whole period, or kept uncovered as a control. Russeting was checked at harvest. The trial confirmed that the period of maximum sensitivity to russeting lies between the second and the fourth week after full bloom, when the fruit diameter is in the range between 15 to 30 mm. Gibberellin concentration was analyzed in uncovered fruitlets picked in the period of maximum sensitivity to russeting. In that period, fruits of the more sensitive clones showed a higher GA7 amount and a lower GA4 amount than fruits of less sensitive clones, where GA4 was predominant. Similar results were obtained analyzing the gibberellin concentration, during the same stage of development, in a completely russeted cultivar ('Reinette Grise') and in a cultivar that never shows russeting ('Rosmarina Bianca'). Therefore, the resistance to russeting seems to be related to a high ratio of endogenous GA4/GA7 during the period of maximum sensitivity
Light Spectrum Affects Growth and Endogenous GAs Content of in vitro Grown Apple Shoots
No full text'Golden Delicious' fruit grown at moderate altitudes on hillsides are less sensitive to russeting than fruit grown in lower lands. Fruit grown on hillsides are also more elongated. Treatments with exogenous gibberellins in the low valley locations produce the same effects on russet and elongation as high altitude, while treating apple trees with GA inhibitors stimulates the opposite response. The hypothesis is made that the different characteristics shown by apples grown at different altitudes are due to their different endogenous gibberellin contents, and that these are, in turn, related to the different solar spectra in the two environments. To investigate if the light spectrum can affect GAs biosynthesis, an in vitro model was studied: propagules of different 'Golden Delicious' clones, cultivated in vitro on substrates with and without GA3, were illuminated with different light spectra, and the growth of plantlets and their gibberellin content were analyzed. Shoot growth, and GA4 and GA7 content were affected by light spectrum, differently in clones with different sensitivity to skin russeting
Old pear varieties in Northern Italy
No full textThe largest collection of Italian pear fruit models (1700 pieces) can be found at the Department of Vegetable Production of the University of Milan, in Italy, most of which were modelled and moulded in the second half of the nineteenth century by the ingenious artist and pomologist, Francesco Garnier Valletti. As many as 309 of these are models of different pear cultivars, with 231 models from different sources. Approximately 500 pear cultivars are represented. This collection shows the great number of pear cultivars grown in Northern Italy 150 years ago. In the same period, Burdin Nurseries published a catalogue with more than 250 commercial pear cultivars and, in 1901, the pomologist Girolamo Molon grew more than 300 pear cultivars in the experimental field of the Royal High School of Agriculture in Milan. Nowadays, the number of pear cultivars commercially grown in Italy is very limited, as more than 70% of total annual pear yield is due to only 4 cultivars (Conference, Abbe Fetel, Beurre Bosc and Doyenne du Comice). The renewed interest in germplasm preservation has led public and private institutions to establish collections of old varieties, many of which are not identified or cannot be identified. One of these collections was established by the Lombardia Region at E.R.S.A.F. The comparison of the unknown fruits with the models of the Garnier Valletti collection, which reproduce not only the shape and colour, but also the size and the weight of the fruit, can be very useful for identifying ancient cultivars
Fruit Quality and Yield of Different Apple Cultivars as Affected by Tree Density
No full textThe evolution of growing techniques and the diffusion of dwarfing rootstocks resulted in a deep revolution of apple culture, not only in traditional Italian apple growing locations on the hills, but also in the plains, where a longer growing season and a higher soil fertility do not allow very high planting density because of the vigour of the trees. With the aim of evaluating the best tree density to achieve high yield and good fruit quality for the most important varieties grown in the Po valley (Golden Delicious, Fuji and Braeburn) an experimental field was established in the spring 1996 in the Po valley. Four Golden Delicious clones were considered (clone B, Smoothee, Reinders and Crielaard), three Fuji (Naga-fu 6, Red Sport, Mori Hofu 3A) and three Braeburn clones (B. standard, Red Braeburn and B. CTIFL). All the plants were on M9 rootstock and spindle trained, at a distance of 4.5 m between rows. The distance of the plants on the row was 75, 100, 150 or 200 cm with corresponding tree density from 1111 to 2962 trees/Ha. Yearly, trunk cross section, total weight and number of fruit of each tree was checked and fruit quality was evaluated by means of physical and chemical parameters at harvest and after 5 months in cold storage. Increasing tree density resulted in higher yield per hectare, but lower yield per tree was evident as soon as the trees began to compete with each other. Highest planting density significantly reduced fruit size and quality, but different results were observed in different varieties and clones. As regards fruit size and quality, variation between years was wider than variation between planting densities: a significant decrease of fruit mass and soluble solids content was observed during the last six years, indicating a progressive competition between trees. The trunk cross size was reduced at high planting density, due both to competition between trees and to the higher productivity (yield per hectare), which limit tree growth. It was concluded that, in the Po valley, the best tree density for the cultivars tested is 2222 trees/ha
Factors Affecting the Proliferation and Rooting of Chestnut in Vitro
No full textIn order to improve shoot proliferation of chestnut and to investigate the influence of nitrogen on the appearance of vitrified shoots, different N and NH4+ levels on MS modified media were compared. The highest proliferation rates and the lowest vitrification incidence were observed on media containing low total N levels and low NH4+/NO3- ratios. Shoots from embryos showed better proliferating and rooting ability compared with shoots from axillary buds of three different clones
Somatic embryogenesis in chestnut
No full textImmature cotyledons of 2 Castanea sativa cultivars and 2 C. crenata X C. sativa hybrids were cultured on 2 media supplemented with various growth regulators. Somatic embryos were obtained only with cv. G9 cotyledons on half-strength MS medium supplemented with either NAA alone or 2,4-D plus benzyladenin
Long Term Effects of Ericoid Endomycorrhizae on the Growth of Micropropagated Plants of Vaccinium corymbosum L. in the Field.
No full textPrevious studies on mycorrhization procedures and the effect of inoculation of 10 selected mycorrhizal fungi (Hymenoscyphus ericae, two isolates of Oidiodendron maius, 6 sterile non-classified mycelia isolated in Italy on Calluna spp., and one sterile mycelium isolated on Vaccinium spp. in France) on rooting and growth of micropropagated plants of 9 cultivars of Vaccinium corymbosum, had shown that the growth and habit of plants and their root development depended on the interaction between the fungus strain and the cultivar. The effect of the interaction between cultivar and fungus strain was maintained, in the first years of field growth, on the size of plants, on the number and length of shoots, and also on the number and length of basal shoots. In the present contribution, the results of eight years of cultivation of the same plants in three different fields are reported. The performance of mycorrhized plants in different soils and environments is compared for plant growth and development. The long term interaction of fungal strain and blueberry cultivar was confirmed: some of the strains that increased the growth of a cultivar were ineffective or even decreased the growth of another one. Moreover, within cultivar, differences in plant growth among fields showed a significant interaction between fungal strain and environmental and soil conditions
The Influence of Ericoid Endomycorrhizae and Mineral Nutrition on the Growth of Micropropagated Plants of Vaccinium corymbosum L.
No full textIn vitro propagation is widely recognized as an excellent way to produce a lot of plants in a short time. Micropropagated plants show a better field performance than those obtained by traditional cuttings: bushier growth habit, increased vigour and number of branches and flowering buds, and higher early yields. As the wild highbush blueberries have symbiotic relationship with endomycorrhizae of Ascomycetes such as those of the genus Hymenoscyphus and Oidiodendron, previous studies on the best mycorrhization procedure and on the effect of inoculation of selected mycorrhizal fungi combined with fertilization on rooting and growth of micropropagated plants of Vaccinium corymbosum were carried out on 9 blueberry cvs with 11 types of mycorrhizae. A remarkable interaction between the fungus strain and the blueberry cultivar were found both on the growth and habit of plants and on root development. The effect of mineral nutrition depended both on blueberry cultivar and on mycorrhizal strain. In the present research, the results of four years of cultivation in the soil of the same plants are reported. The effect of the interaction between cultivar and fungus strain is still remarkable on the size of plants, on the number and length of shoots, and also on the number and length of basal suckers. As for nutrition, the trials confirm the positive role of P on the growth of plants, and the multiple interaction between cultivar, fungus and fertilizer
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