E. Antognozzi

Influence of CPPU on carbohydrate accumulation and metabolism in fruits of Actinidia deliciosa (A. Chev.)

Abstract A trial was carried out to evaluate the influence of N-(2-chloro-4-pyridyl)-N′-phenylurea (CPPU), a diphenylurea derivative cytokinin, on kiwi productivity, on carbohydrate accumulation and metabolism and on post-harvest fruit performance. CPPU (20 ppm) was sprayed on fruitlets inside the canopy 2 weeks after full bloom (AFB). CPPU influenced fruit growth soon after treatment and, at harvest, treated fruit weight and, consequently, yield per vine were about 25% higher than the control. During fruit growth, soluble sugars (glucose, fructose and sucrose) were higher in treated fruits than in the control ones. In the first period of fruit development glucose was the most abundant carbohydrate and CPPU treatment increased the fruit glucose content significantly. During the period of starch accumulation, treated fruits showed a higher starch content and a higher ADP-glucose pyrophosphorylase activity. Starch accumulation started earlier in treated fruits than in the control ones. At the end of the growing season the degradation of starch in treated fruits started earlier and/or was faster than in the control ones, so that at harvest treated and control fruits contained the same amount of starch. As a consequence, treated fruits at harvest had higher contents of soluble sugars. This indicates that CPPU induced faster and/or advanced fruit ripening. The chlorophyll content was higher in CPPU treated fruits. During storage, the differences in carbohydrate content disappeared and treated fruits performed as well as control ones, maintaining good quality for up to 6 months.

Effect of irrigation on fruit quality of table olives (Olea europaea), cultivar ‘Ascolana tenera’

Abstract This trial was carried out to study the relationship between irrigation and vegetative and productive activity and fruit quality of table olives (Olea europaea), cultivar ‘Ascolana tenera’. Irrigation every 15 days, with c. 0.4 m3/tree at each irrigation, from the end of June to mid September, induced higher leaf surface area, photosynthesis, and transpiration during the entire growing period compared to the control. This led to an overall positive effect on total production per tree. Fruit weight, volume, and pulp/pit ratio all increased. Water availability influenced cell division more than cell expansion. Fruit shape was not influenced. Irrigation had no substantial delaying effect on ripening. With irrigation, pulp water content increased, and firmness and fruit sugar content decreased slightly, but after preservation in brine, pulp water content, and the sensory characteristics of the olives (flavour, texture, and detachment of the pulp from the pit) from irrigated and non‐irrigated olives w...

Influence of light exposure on characteristics and storage life of kiwifruit

Abstract Quality and storage life of kiwifruit were investigated on fruits from shaded and exposed positions of the canopy and on fruits artificially shaded and grown in absence of light. At harvest the fruits grown in high light intensity have a high quality and can be stored for a long time; after 25 weeks of cool storage they have a soluble solids concentration > 14° Brix and a flesh firmness of c. 10 N. Fruits from shaded positions of the canopy showed significantly lower mean fresh weight and chlorophyll content (‐35%); at harvest and during storage they were slightly but consistently less firm and had lower soluble solids concentration than exposed fruits. Artificial shading of individual fruit for most of the growing season significantly reduced chlorophyll content in the mesocarp (‐77%), starch and alcohol‐soluble sugars concentration, flesh firmness, soluble content and dry matter, whereas the titratable acidity was significantly increased. The storage life of artificially shaded fruits was signi...

The role of air temperature in determining dormancy release and flowering ofCorylus avellana L.

Summary7 years of airborne pollen monitoring in Perugia (central Italy) were used to determine the temperature requirements to break dormancy and to resume growth and bloom ofCorylus avellana L.,Corylus needs 1000 chill-units to complete its dormancy and this value, in the Perugian area, is met by the end of December or the first days of January. MoreoverCorylus trees require 220 growth degree hours before they are able to flower. If air temperature is high, this value can be achieved in only 10 days, but if the temperature remains too low, the heat accumulation can require up to 35 days. With these parameters it is possible to build a model to predict the date of the beginning ofCorylus avellana pollen season.

Effects of leaf to fruit ratios on fruit growth in chestnut.

In Castanea sativa Mill. cv. Santa Restituta, 10 days after full bloom, defoliation to give leaf-to-husk ratios of 2/1, 4/1, 7/1, 10/1 and 14/1 was performed on both girdled and ungirdled shoots fully exposed to the sun. The results showed that assimilates can be easily translocated and it is necessary to have about 10 leaves well exposed to light per husk (about five leaves per fruit) to ensure normal fruit development. Fruit is a stronger sink than shoot reserve tissues. A feedback inhibition of photosynthesis at high leaf-to-husk ratios is suggested.

Thidiazuron affects fruit growth, ripening and quality of Actinidia deliciosa

SummaryThe effects of thidiazuron (TDZ) on growth, quality and ripening of kiwifruits were evaluated by comparison with untreated (control) and CPPU (cytokinin) treated fruits. Two weeks after full bloom (AFB), TDZ at 5, 10 or 20 ppm and CPPU at 20 ppm were applied to fruits by dipping them for about 5.s in aqueous solutions of the two compounds. TDZ remarkably increased fruit growth soon after application. The increase in size levelled off at 10 ppm and no further improvement in fruit size resulted from the 20 ppm treatment. At harvest, TDZ treated fruits, depending on the concentration, were 50% or 60% heavier than untreated ones. All TDZ concentrations used also gave a large (+44%) and similar increase in fruit dry weight. TDZ did not cause significant variations in the number and weight of seeds. TDZ caused some modification in fruit shape. It increased the percentage of fruits having a protruded distal end and tended to decrease the fruit length/average diameter ratio, especially at the higher concen...

Influence of sink competition on peduncle histogenesis in kiwifruit

Abstract Just before flowering, inflorescences with one terminal and two lateral flowers were thinned according to the following treatments: (1) no thinning (control); (2) inflorescence with a main and one lateral flower; (3) inflorescence with only the main flower; and (4) inflorescence with only a lateral flower. The terminal fruit grew at the same rate in all conditions. A single lateral fruit did not grow more than the controls. At harvest the main fruit showed higher weight Histo-anatomical observations showed that primary xylem differentiation on the main flower peduncle appeared earlier than in laterals. When just a lateral flower was maintained, there was formation of secondary xylem only in distal parts of the peduncle. The removal of the main fruit did not change the vascular differentiation of lateral peduncles. The terminal peduncle showed a radial arrangement which did not develop in lateral ones when the main flower was cut off. Therefore, in the inflorescence, fruit growth may be partly lim...

Thidiazuron increases current-year fruit size and production in Actinidia deliciosa without decreasing return bloom

Summary The effects of whole-crown application of thidiazuron (TDZ), applied two weeks after full bloom, at the concentrations of 0 (control), 2 or 10 ppm, on vine yield, fruit quality and on next-season potential yield of Actinidia deliciosa ‘Hayward’ were evaluated in 1998–99. Fruit growth increased rapidly after TDZ application. Fruit fresh weight and yield increased by about 13% and 22% with the 2 and 10 ppm concentration, respectively. These responses were associated with only small changes in fruit shape, with 10 ppm-treated fruits slightly rounder than the control. During ripening, TDZ did not affect fruit soluble solid content, flesh firmness or concentration of non-structural carbohydrates. No effect was observed on the amount of winter pruning, entity of bud burst, percent of fertile buds, number of inflorescences per fertile bud or percent of vegetative buds. These results show that TDZ can be applied to the whole crown to increase fruit size and yield, without affecting fruit quality or the next-season’s crop.

Influence of assimilate availability on translocation and sink strength in kiwifruit

Abstract Defoliation treatments on 2, 4, 8, and 16 whole canes per vine corresponding to an average defoliation intensity (DI) of 5.5, 10.2, 24.4, and 48.7% were carried out on kiwifruit (Actinidia deliciosa) vines with the same bud load and fruit number. Negative effects on fruit weight and concentration of soluble solids were recorded beginning at 24.4% DI. In comparison to undefoliated canes, the defoliated ones showed lower fruit weight from 10.2% DI and higher fruit drop from 24.4% DI. In the year following defoliation treatments, budburst was reduced at 24.4% DI, whereas differences between defoliated and undefoliated canes appeared at 48.7% DI. The percentage of fruiting shoots was reduced in comparison to the control, starting at 24.4% DI, but the differences between defoliated and undefoliated canes started at 10.2% DI. When there was an abundant supply of assimilates, translocation to fruits on defoliated canes occurred without limitations. When the availability of assimilates was reduced, the d...