Poster *INRA Unité d'Amélioration des Espèces Fruitières et Ornementales, Centre INRA d'Angers Diffusion du document : INRA Unité d'Amélioration des Espèces Fruitières et Ornementales, Centre INRA d'Angers | National audience

Communication orale *INRA Centre d'Angers (FRA) Diffusion du document : INRA Centre d'Angers (FRA) <br/>Communication orale *INRA Centre d'Angers (FRA) Diffusion du document : INRA Centre d'Angers (FRA) | National audience

We investigated water relations of fruit cracking in single-truss tomato (Lycopersicon esculentum Mill.) plants grown hydroponically in a greenhouse. At 24d after anthesis, the water potential of the culture solution was changed from -0.06 MPa (control plants) to -0.36 MPa (stressed plants). The water status of the culture solution and plant tissues was measured with an isopiestic thermocouple psychrometer. Fruit cracking decreased from 80% of fruit in the control to 30% in the stressed plants. The water potential gradient between fruit flesh and water source was greater in the control plants than in the stressed plants. Between predawn and morning, turgor increased in the fruit flesh in the control plants but not in the stressed ones. The hardness of the fruit skin was not different between stressed and control plants. These results indicate that the water potential gradient and increased turgor in the tissues might trigger fruit cracking in single-truss tomato plants

This study was carried out to determine the effects of some thinning methods (NAA, NAAm and hand thinning) on ratio of fruit thinning, physical and chemical characteristics of fruit of Golden and Starking apple varieties. Thinning were increased to fruit thinning ratios. Fruit weight, fruit volume and fruit dimensions increased with thinning application compared to control. Besides, there were statistically difference about some chemical characteristics of fruit such as TSS, titrable acidity, total and reducing sugar when compared to control depending on thinning applications in both of cultivars

Effect of aqueous solutions spray of cobalt sulphate, cobalt nitrate or silver nitrate (0, 50, 100, 200 ppm), and free radical scavangers viz. n-propyl gallate, sodium benzoate (0, 100, 200, 400 ppm) and 2,4-D (10 ppm) on fruit drop and yield in mango (Mangifera indica L.) cv. Langra was investigated. The panicles on the trees were sprayed to run off on March, 8 (15-20 days fruit set) and agian a week later on March, 15. All spray treatments of cobalt, silver, n-propyl gallate and soium benzoate reduced the fruit drop as compared with the control trees. The spray applications of cobalt sulphate (200 ppm) has significantly reduced fruit drop (97.25 percent) as compared to control (99.90 percent) and earlier recommended treatment of 10 ppm 2,4-D. The fruit drop was also significantly reduced with the spray treatment of silver sulphate (200 ppm) as compared to the control and 2,4-D (10 ppm) treatment. The spray application of n-propyl gallate or sodium benzoate did not prove better as compared to the treatments of cobalt and silver to alleviate fruit drop. All treatments, which reduced the fruit drop, have improved the fruit yield. The fruit quality was not affected significantly by any of the treatment as compared to control.

The seed-fly Ophiomyia lantanae (Froggatt) (Dip.: Agromyzidae) is one of the most widely established biological control agents for lantana. Larvae of O. lantanae are found in the lantana fruit, in which they attack the fleshy endosperm and pupate in either the seed receptacle or a chamber within the fruit. This paper questions the impact of the seed-fly as a biological control agent in Australia. Fruit were dissected and tested with tetrazolium chloride to assess the viability of embryos. Of 3300 fruit dissected, none of the embryos were affected. Dissections and testing of fruit of different ages suggest that embryos are viable for a short period, regardless of whether the fruit is fly-infested.

Harvested nectarine fruit [Prunus persica (L.) Batsch 'Flavortop'] were held for 5 days at 20 degrees C, or stored at 0 degrees C either immediately (control), or after 2 days at 20 degrees C (delayed-cooling). Observations were conducted after removal from storage for 1, 3, or 5 weeks and a shelf life of 5 additional days at 20 degrees C. After 5 weeks storage, 87% of control fruit developed woolliness (mealiness in texture accompanied by dry tasting fruit as a result of reduced juice content), while only 7% of delayed-cooling fruit showed signs of woolliness. Firmness of fruit in the delayed-cooling treatment was less at the beginning of ripening than control fruit, but after shelf life in both treatments, fruit reached the same final softness. Expressible juice was lower in woolly fruit (46%) than in healthy fruit (65%). Along with woolliness, viscosity of the resuspended alcohol insoluble residue (cell wall material) of expressed juice increased, implying accumulation of large molecular-weight polymers. The high performance liquid chromatography profile confirmed there were more large pectin polymers (2000 to 76 Ku) in the cell wall components of juice from woolly fruit and a lower arabinose content in these polymers reflected greater side chain removal from pectins in the juice of woolly fruit. Accumulation of larger sized pectin polymers along with high viscosity correlated with lower polygalacturonase activity in woolly fruit. Degradation of soluble pectin released into the juice of woolly fruit may have been impeded by repressed polygalacturonase activity.

'Cortland' apples (Malus xdomestica Borkh.), either untreated or treated with diphenylamine (DPA), were stored for 120 days in air at 0 degree C. Peel samples were taken from these fruit immediately after storage, placed in glass vials and incubated for 48 hours, or were isolated from fruit held 2 to 72 hours at 22 degrees C and incubated in the vials for 2 hours. Emission of 3,7,11-trimethyldodeca-1,3(E),6(E),10- tetraene, known as trans,trans-alpha-farnesene, or simply alpha-farnesene, and its oxidation product, MHO, were measured in the vial headspace. alpha-Farnesene content in the gas phase of vials with peel samples reached a maximal level 2 hours after vials were sealed and was higher in DPA-treated than untreated fruit. The content of alpha-farnesene in the vial headspace remained unchanged for DPA-treated fruit peel during the 2-day holding period. However, alpha-farnesene declined rapidly after 10 hours incubation for control samples. Incubating peel samples of control fruit under N(2) atmosphere prevented the decline in alpha-farnesene. The MHO release by the peel of control fruit was rapid during the first 2 hours and continued to increase for 24 hours. In contrast, the MHO released from DPA-treated fruit peels was 8000-fold lower than from peel samples of control fruit. The increase in vapor phase MHO was concomitant with peel browning in controls. For whole fruit held at 22 degrees C for 2 to 72 hours, cumulative MHO release from fruit peels followed a pattern that was similar to the pattern of superficial scald development in these fruit.

The yeasts Cryptococcus infirmo-miniatus, Cryptococcus laurentii, and Rhodotorula glutinis, applied to Bosc and d'Anjou pear fruit in the field 3 weeks prior to harvest, maintained high population levels through harvest, while populations of Candida oleophila declined after 1 and 2 weeks, and by harvest were not significantly different from total yeast populations on untreated fruit. Yeasts were sprayed individually on fruit at concentrations of 1 to 3 x 10(8) CFU/ml, with approximately 2 ml applied per fruit. Initial population sizes for all four species averaged 5 x 10(6) CFU per fruit. C. infirmo-miniatus provided the most consistent decay control in fruit treated 3 weeks before harvest. C. infirmo-miniatus and R. glutinis also provided significant postharvest decay control in Bosc fruit treated 1 day before harvest.