Norberto Gariglio

Loquat fruit size is increased through the thinning effect of naphthaleneacetic acid

The thinning effect of naphthaleneaceticacid was examined in loquat trees (Eriobotryajaponica Lindl.). The effect depended on theconcentration applied and on the treatment date. Themost effective treatment found to thin fruit andincrease the average fruit size was the application of20 mg l−1 of naphthaleneacetic acid 10–15 daysafter anthesis. Treatment reduced the fruit resistanceto puncturing and improved total soluble solidsconcentration and coloration and, consequently,harvest time was markedly advanced.

Effect of the synthetic auxin 2,4-DP on fruit development of loquat

Application of the butylglycol ester of 2,4-DP increased final fruit size in loquat without causing fruit thinning. Its effectiveness depended on the concentration applied and treatment date. When applied at the onset of the cell enlargement fruit stage, 25 mg l−1 was the most effective treatment. Fruit diameter distribution showed a significant shift to the larger size for treated trees; further, fruit colour break and maturation were encouraged and harvest time was earlier than in untreated trees.

Histological and physiological study of purple spot of loquat fruit

Abstract We describe the structure of purple spot of loquat (Eriobotrya japonica Lindl.) by comparison between affected and non-affected fruit, using light and scanning electron microscopy (SEM) procedures. Water permeability rates of isolated cuticles and mineral fruit composition were also measured. SEM and light microscopy show that purple spot initially appears at the deepest rind cell layers as a fringe of compact and empty cells. As purple spot intensity increases, the number of affected cells also increases to include all rind tissue. Affected cells show a shrunken cytoplasm with an extrusion of cellular material out of the plasmalemma. Flesh cells are not damaged. The cuticle of affected fruit showed no sign of damage or disruption and the water permeability of isolated cuticles showed no consistent differences between injured and healthy fruits. Mineral composition in flesh tissue of affected and healthy fruit was similar. However, in epidermal tissue concentration of K, Fe and Cu were higher in affected fruit than in healthy fruit.

Effects of fruit thinning on fruit growth, sugars and purple spot in loquat fruit (Eriobotrya japonica Lindl.)

Summary This work examines the effects of fruit thinning on fruit growth, sugar accumulation and incidence of purple spot in loquat (Eriobotrya japonicaLindl.). Thinning increased fruit growth and sugar contents of fruit. As total sugar concentration correlated significantly with the proportion of affected fruit, we conclude that thinning increased markedly the proportion of fruit affected by the disorder. Carbohydrate accumulation may be the factor responsible for the incidence of purple spot by accelerating fruit development.

The influences of environmental factors on the development of purple spot of loquat fruit (Eriobotrya japonica Lindl.)

Abstract Loquat purple spot development was studied in the province of Alicante (Spain) during seven consecutive years, and in five commercial orchards differing in harvest time for 2 years. The main environmental factors influencing this disorder were identified. Purple spot incidence showed similar development patterns during the 7 years studied. The highest incidence occurred at the beginning of harvest time, affecting 25–30% of the fruit, followed by a sudden decrease to about 5–10% affected fruit. Early-maturing orchards had higher purple spot incidence at the beginning of harvest time (60%) than late-maturing orchards ( Low day temperature at fruit colour break was the main environmental factor correlating with annual purple spot incidence, both among years and among selected orchards. Heating plants in a greenhouse during the night greatly reduced incidence of the disorder. Sunshine also affects purple spot occurrence. The amount of affected fruit was significantly reduced, and even nullified, by keeping direct sunlight off the fruit.

Effect of branch scoring on fruit development in loquat

Summary Branch scoring of loquat (Eriobotrya japonica Lindl.) at the 702–704 growth stage of the BBCH-scale increased fruit size at harvest and caused a significant shift in the distribution of fruit diameters to the larger sizes. Fruit from scored trees grew faster and reached commercial colour and flesh softness earlier than fruit from non-scored trees, and therefore could be harvested earlier. No other fruit characteristics were altered significantly by scoring. As the number of fruit was not modified, but fruit weight increased significantly, there was a significant increase in yield on trees scored at this growth stage. Scoring was as effective as ringing at improving fruit development.

Crop loading studies on ‘Caricia’ and ‘Eva’ apples grown in a mild winter area

The crop load level of an apple (Malus × domestica Borkh.) tree impacts fruit yield and quality parameters, tree vigor and biennial bearing. The optimal crop load is that which allows for consistent annual cropping and fruit quality acceptable to the market. We evaluated the effect of crop load on yield and fruit quality of two low-chill apples cv. ‘Caricia’ and ‘Eva’, growing in a mild winter area. During 2010 and 2011 crop load was manually adjusted from 2 or 3 to 17 fruits cm−2 of trunk cross-sectional area (TCSA). Fruit yield was positively related to crop load in both cultivars but mean fruit weight diminished as the crop load increased. For both cultivars, the production of non-commercial and small-sized fruit increased, whereas production of middle-sized fruit diminished as the fruit load increased. Shoot length was not affected by crop load in ‘Eva’ whereas it was reduced in ‘Caricia’. Red skin color (RSC %) had a quadratic response to crop load in ‘Caricia’. On the other hand, the RSC % of ‘Eva’ fruit was adjusted to a negative logarithmic model as an effect of crop load increment. No biennial bearing was observed in either cultivar. This research study suggests that the maximum limit of crop load for both cultivars is 7 fruits cm−2 of TCSA, and the lower limit of crop load was 3 fruits cm−2 of TCSA for ‘Eva’ and 5 fruits cm−2 of TCSA for ‘Caricia’.

Assimilate partitioning between the flesh and the rind is responsible for purple spot in loquat fruit

Summary This work reports on the relationship between purple spot and the balance of sugars between flesh and rind tissues in loquat trees (Eriobotrya japonica Lindl., cv. ‘Algerie’) in Alicante, Spain, as affected by thinning, night temperature, and exposure to sunlight. In Spain, 15% of annual loquat fruit production is affected by purple spot. From fruit set to colour break, the total sugar concentration (TSC) in the flesh of fruit from non-thinned trees increased by 170%, compared with an increase of 803% in fruit from trees thinned to one fruit per panicle. Thinning had a similar effect on TSC in the rind. In the flesh, sucrose and glucose concentrations increased up 7.5- and 24-fold, respectively, after thinning; whereas fructose and sorbitol levels increased 2.5- and 1.2-fold, respectively. In the rind, sucrose ( 14.5), glucose ( 38), fructose ( 3.6) and sorbitol ( 1.3) also increased. At colour break, the gradient of TSC between the flesh and the rind increased from 143 mg g–1 DW to 417 mg g–1 DW due to thinning, and correlated with the incidence of purple spot. Maintaining night temperatures above 15ºC, or wrapping the fruit, reduced the gradient of TSC from 396 mg g–1 DW to 279 mg g–1 DW and from 363 DW to 296 mg g–1 DW, respectively, and reduced spotting. There was a significant relationship (R2 = 0.91) between the incidence of purple spot and the gradient of TSC between the flesh and the rind in the three experiments.

CARGA ÓTIMA DE FRUTOS NA MACIEIRA ‘PRINCESA’ DE BAIXO REQUERIMENTO EM FRIO INVERNAL:RESULTADOS PRELIMINARES

The aim of this study was to evaluate the effect of crop load on yield, fruit size, vegetative growth and return to bloom of low-chill apple (Malus × domestica Borkh.), cv. ‘Princesa’. During 2009 and 2010 crop load was manually adjusted from 1 to 9 fruits per unit of trunk cross-sectional area (TCSA). Fruit yield was positively related tocrop load, but mean fruit weight decreased with increasing crop load. The proportion of small and middle-sized fruits increased with rising crop load reaching 10% and 35% respectively of the total yield at the highest crop load. However the proportion of large-sized fruits did not change with the increase in crop load. Shoot length at 60 days after harvest was negatively related to crop load whereas return to bloom was not affected. These results demonstrates that the optimum crop load for ‘Princesa’ apple ranges between 5 to 9 fruits per unit of TCSA.

FACTORS AFFECTING PHENOLOGY OF DIFFERENT Citrus VARIETIES UNDER THE TEMPERATE CLIMATE CONDITIONS OF SANTA FE, ARGENTINA

The aim of this study was to characterize the phenology of different sweet orange, tangerines and tangerine hybrid varieties growing under the temperate climate conditions of Santa Fe Province, Argentina. Phenological stages were observed weekly during five consecutive years using a BBCH (Biologische Bundesanstalt, Bundessortenamt and Chemical industry) scale adapted for Citrus trees. All varieties showed a winter rest period from June to August. ‘New Hall’ and ‘Navelina’ varieties were the first to reach sprouting stage, whereas ‘Okitsu’ was the last. Inception of flowering occurred from August 13th to September 6th; and full bloom from September 12th to October 2nd. Fruit harvest started with the ‘Okitsu’ cultivar in March, and continued over a 7-month period. Interannual variation for inception of sprouting was high (44 days), and sprouting was correlated with both thermal accumulation (above 13oC) and the amount of solar radiation measured during July (p<0.0001; r2=0.79). Navel oranges and the ‘Murcott’ hybrid bloomed 5–15 days earlier than other varieties, increasing probability of damage by late frosts.