Fruit weight and morphological characteristics of `Meeker' red raspberry (Rubus idaeus L.) fruit, including drupelets (height, diameter, number), receptacle cavities (depth, diameter), and pits (individual weight) were measured five times in 1988. Fruit strength, as measured by compression, was recorded. The relationship of fro-it weight to fruit strength had linear and quadratic components. Fruit weight was correlated with fruit strength, drupelet height and number, receptacle cavity depth and diameter, and individual pit weight. Besides fruit weight, fruit strength was correlated with drupelet diameter and number, receptacle cavity depth, and individual pit weight. Drupelet number, receptacle cavity depth, and individual pit weight provided the largest component contribution to fruit strength, as determined by path analysis.
Weight and morphological characteristics of red raspberry (Rubus idaeus L.) fruit, including drupelets (height, diameter, number), receptacle cavities (depth, diameter), and pits (individual weight), were measured on 78 seedlings from the cross `Chief' × `Chilliwack'. Fruit strength, as measured by compression, correlated with fruit weight, drupelet number, receptacle cavity depth, and individual pit weight. Fruit weight was positively correlated with all morphological characteristics. Individual pit weight, drupelet height, and drupelet number provided the largest component contributions to fruit strength as measured by path analysis.
Morphological characteristics of whole red raspberry fruit (weight, density), drupelets (height, diameter, number), receptacle cavities (depth, diameter), and pits (individual weight) were measured three times in 1983 on five cultivars of red raspberry (Rubus idaeus L.) and three times in 1984 on 10 cultivars. Fruit strength, measured by compression and cohesion, was also recorded. Across all genotypes, compression and cohesion measurements were highly correlated with fruit weight, drupelet height and number, receptacle cavity depth, and individual pit weight. Drupelet height, drupelet number, receptacle cavity depth and width, and individual pit weight provided the largest component contribution to both cohesive strength and compression strength by path analysis.
The effects of delayed precooling on fresh red raspberry fruit during storage was determined. Precooling was delayed for 0.5 to 12 hours, followed by cold storage for 8 days, with subsequent storage at 20C for 24 hours. Weight loss was greater with increasing delays of precooling. Fruit that lost more weight during the delay period lost less during the subsequent S-day storage at 0C. The exception was fruit held for 12 hours before precooling. Weight loss during the final 24 hours at 20C showed no pattern. Cumulative weight loss at the end of the storage treatments was similar regardless of delay of precooling. Fruit strength was reduced by any delay of precooling. The effect of delayed precooling on color was not consistent in the 2 years using different cultivars. The results indicate that fruit should be precooled as quickly as possible after harvest for long-distance fresh marketing.
Fruit strength in red raspberry was measured using a cohesion method that determines the force required to pull a fruit apart. This method was compared to the compression method, which measures the force required to flatten the fruit. Fruit maturity significantly affected accuracy; the cohesion method was most variable for ripe fruit. A relatively low coefficient of variation across all maturity types indicates that the compression method is preferable for between-maturity comparisons, using a log transformation to produce variance homogeneity. With both methods, red ripe-stage raspberries showed significant differences between clones; the coefficients of variation for each method were similar within each clone. Variances were homogeneous using either method. The cohesion method gave relatively low absolute measurements that were highly correlated with those obtained using the compression method. Therefore, either method should be acceptable for measurements made within one maturity type.
Fruits of red raspberry (Rubus idaeus L.) cultivars were harvested at the red-ripe stage and stored at 0C for up to 36 days. Firmness and titratable acidity generally decreased during storage, while anthocyanin and pH generally increased. Cultivars differed in rates and direction of change in firmness and pH during storage, and means differed at successive storage periods. Cultivars generally maintained their at-harvest ranking through storage in all characters. Cultivars differed in respiration rate. Respiration rate was positively correlated with ethylene evolution, rot, weight loss, and change in soluble solids concentration after 36 days in storage, and negatively correlated with change in firmness after all storage periods.
L-77, a nonionic organo-silicone block copolymer surfactant, significantly increased [14C]GA3 uptake and physiological effects of GA3 on ‘Marsh’ seedless grapefruit, as compared with the commonly used surfactant Triton B 1956. Effects on fruit strength at harvest were assessed by testing rheological parameters and evaluating peel color. Corroborating results also were obtained in field trials with ‘Minneola’ tangelo and ‘Clementine’ tangerine. Using L-77, even one single fall application of 1 ppm GA3 proved commercially effective.
Scanning electron microscopy was used to measure epidermal hairs and drupelet morphology of raspberry fruit. Significant differences were found among cultivars and selections in drupelet size, total contact area between drupelets, and contact area with hairs between drupelets, hair density index, and hair length. Drupelet numbers also differed. Fruit strength, as measured by cohesiveness, was related to contact area between drupelets, whether hair-covered or not, in conjunction with total drupelet number. Hair density contributed to cohesion in some years with certain cultivars. Resistance to compression was most consistently correlated with total drupelet area and contact area between drupelets alone and in conjunction with hair density.
. Furthermore, they oriented the fruit so that the stem axis of the fruit was perpendicular to the force applied, whereas in our tests, the stem axis was parallel to the direction of the force. In a multiyear study to determine citrus fruit strength
large fruit in these zones is indicative of improved fruiting strength. It is plausible that some combination of bud quality and improved P n led to these differences. Khemira et al. (1993) proposed that greater than 30% of full sunlight is necessary