Average Fruit Research Articles

St. Williams, Scotland and Selkirk strawberries

St. Williams strawberry (Fragaria × ananassa Duch.) has average size fruits with a high yield. The fruits have high quality and are outstanding for freezing. It is recommended as suitable for processing. Scotland strawberry has large extremely firm fruits, is very late maturing and can be decapped by machine. It is recommended for machine harvesting for processing. Selkirk has large, firm, high quality fruits with good yields. It is suitable for both the fresh and processing markets. Key words: Cultivar description, processing, machine harvesting

The development and effects of nitrogen deficiency in field-grown kiwifruit (Actinidia deliciosa) vines

The development and effects of nitrogen (N) deficiency in kiwifruit (Actinidia deliciosa ‘Hayward’) vines planted at three densities (25.0, 12.5 and 8.33 m2 vine−1) were examined in a long term (1982 to 1989) field experiment in which N was applied at rates from 0 to 200 kg N ha−1 year−1. The rate of applied N significantly affected leaf N concentrations every year from 1985 onwards, and the average leaf N concentrations declined throughout the experiment. Fruit N concentrations varied significantly with the level of applied N as early as 1986. The average fruit N concentrations varied strongly between years, and were inversely proportional to the fruit number (per m2), indicating that, after fruit set, growth of individual fruit was relatively insensitive to the vine N status. Effects of N supply on fruit yields resulted mostly from changes in fruit number (per m2). For vines planted at the high density, fruit yields responded significantly to the level of applied N each season from 1986 onwards. In any year, maximum fruit yields for vines planted at the high density were associated with leaf N concentrations (20 weeks after bud burst) of at least 1.8 mmol g−1. For vines planted at low density, significant yield responses to the level of applied N were not recorded until 1988, and maximum yields in that year were associated with leaf N concentrations of at least 1.4 mmol g−1. The delayed expression of effects of N deficiency on fruit yields for vines planted at low density appeared to follow a shift in partitioning of resources in favour of fruit growth. This shift in partitioning did not appear to be sustainable, and by 1989 the fruit yield response to applied N continued to the highest N level tested. In that year, the leaf N concentration associated with maximum yield was 1.8 mmol g−1, the same as that recorded throughout the experiment for the vines planted at high density. In the last two seasons of the experiment, leaf necrosis developed extensively on vines receiving less than the highest rate of N. This necrosis appeared to be premature senescence resulting from N deficiency. Leaf chloride (Cl) concentrations increased significantly with increasing severity of N deficiency, but were never more than those associated with Cl toxicity. While N supply significantly affected fruit firmness immediately post-harvest, there were no significant effects on fruit firmness after 12–20 weeks storage.

Response of pre-harvest drop of grapefruit on two rootstocks to 2,4-D, MCPA and gibberellic acid

Several formulations, concentrations and timings of sprays of 2,4-D (2,4-dichlorophenoxyacetic acid) and MCPA (4-chloro-2-methyl phenoxyacetic acid) were tested for their ability to reduce pre-harvest drop of late hanging Marsh grapefruit growing on rough lemon (Citrus jambheri) and trifoliata (Poncirus trifoliata) rootstocks at Dareton in south-western New South Wales. Gibberellic acid was also tested in several timing combinations with 2,4-D for its ability to improve the quality of late hanging fruit. On rough lemon the established standard treatment of 2,4-D at 20 ppm applied in mid-May was as good or better than all other treatments. On trifoliata this standard spray was again as effective as all others in preventing drop up to mid-November, but a similar spray applied in midJune was more effective from mid-November to mid-December. MCPA applied at 10 or 20 ppm in mid-May was not as effective as the standard spray. The best treatments reduced the average cumulative fruit drop, of 39% on trifoliata and 70% on rough lemon, by at least a half. When gibberellic acid at 10 ppm was added to the standard mid-May spray of 2,4-D, or when it followed it in mid June, it improved the colour and appearance and reduced the rind thickness and puffiness of late hanging fruit.

Título en español.

Durante 7 años se estudió el comportamiento de la acerola (Malpighia punicifolia L.) en la Subestación de Castañer ubicada en el centro de la región cafetalera de Puerto Rico. Las plantitas de acerola provinieron de semillas del clon B-17. Se sembraron en el campo en un tipo de suelo Alonso arcilloso cuyo pH era alrededor de 5.0. Como el terreno era en declive, la siembra se dejó sin cultivar para evitar la erosión, aunque otras prácticas como la erradicación de los yerbajos, el abonamiento, etc., se atendieron debidamente. Hubo gran variación entre los árboles de acerola en cuanto a tamaño, diámetro del dosel, número y grosor de las ramas escalonadas, longitud de las ramas laterales y número de espolones. Empezaron a producir frutas cuando tuvieron alrededor de 3 años. La cosecha empezó en abril, continuó hasta noviembre y llegó a su apogeo en agosto. Los árboles también demostraron gran variación en sus rendimientos de frutas. A través de un período de 3 años, el promedio anual de producción por árbol fluctuó entre 205.2 y 481 onzas. En promedio, los árboles de acerola demostraron una gran variación en el diámetro y peso de las frutas. Sin embargo, no varió mucho el diámetro ni el peso de las frutas cosechadas de los mismos árboles en fechas distintas. Estos árboles sí revelaron una gran variación en el contenido de vitamina C de sus frutas. Las bien maduras tenían menos cantidad de vitamina C que las que, en el mismo árbol, habían madurado sólo parcialmente. Las frutas se utilizaron para preparar jugos y jaleas en pequeña escala. A muchas personas les gusta comer la fruta fresca, especialmente las más grandes y las menos ácidas. Por lo demás, los árboles bajo estudio no sufrieron daño importante debido a enfermedades o a plagas de insectos. Este estudio indica que la acerola podría cultivarse comercialmente en la región cafetalera de Puerto Rico, si la producción lograra venderse para fines industriales.

A tomato selection experiment

All 153 crosses between 18 tomato varieties were grown in F1, F2, F3 and F4. The F2, F3 and F4 were derived by selfing one plant of the previous generation. The F2 plant chosen to give the F3 was selected (1 in 20) for early yield; and the F3 plant chosen to give the F4 was similarly selected. Flowering date was an unsatisfactory character. In crosses segregating for the Mendelian gene ‘uniform’, a significant excess of heterozygotes was selected. The parents transmitted variability of yield (as well as average yield) to their offspring. The division of yield into its components fruit number and fruit size is useful because (1) much of the heterosis in yield can be viewed as a combination effect between these components, (2) the components responded differently to selection, (3) different components showed phenotypic dominance in different directions. The average yield and fruit number responded as expected to selection; fruit size did not. The F1 generation means for all three characters exceeded the parental means; but the crosses were grouped more compactly about their generation mean than were the parents, so that heterosis rarely occurred in crosses involving the best parents. The yields of each cross were analysed into parental main effects (general combining abilities) and interactions (specific combining abilities). No useful prediction of interactions could be made in any generation, either from the same generation in different years or from different generations in the same year. The main effects (general c.a.) were analysed into a part due to regression on parental yield, and a deviation from that regression. No useful prediction of the deviations from parental regression could be made in generations which had responded to selection. The actual advance under selection of different crosses, although not uniform, was unpredictable. During advance under selection, the parental means gave predictions of the (relative) performance of each generation's crosses which were as good as predictions based on the previous generation. This may, of course, be connected with the fact that the parents were inbred and that the amount of heterozygosity decreases in each successive generation. These results indicate, therefore, that in an inbreeding species propagated by seed, the early hybrid generations tell us nothing more than do the parental yields about the relative performance of the inbred lines that can be selected from those hybrids. (This generalization from Lycopersicon esculentum to inbreeders as a whole may, of course, be false.) The relative performance of F1 hybrids, on the other hand, is better predicted from other F1 crosses involving the parents concerned than from the yields of those parents. There was phenotypic dominance of high yield, large fruit number and low fruit weight. The extent of this dominance was not enough to invalidate the analysis by general combining abilities; and since it varied from year to year and from generation to generation, the emphasis that should be given to the top-parent (in contrast to the bottom-parent) in predicting the yields of crosses after selection, is as yet unpredictable.

An Operation in Practical Control of Codling Moth in a Heavily Infested District—Third and Final Report1

This paper reviews the results of a three year cooperative effort against the codling moth, Carpocapsa pomonella, in a heavily infested district near Glassboro, New Jersey. This cooperation existed between a group of more than twelve growers, whose properties involved a total of over 1400 acres of bearing apple, and the New Jersey Agricultural Experiment Station. In 1925, which is the year previous to the inception of this effort, the average percentage of fruit free from codling moth at picking time was 47.4. In 1926 the average clean fruit at picking time in a crop of 280, 200 bushels was 68.8%. In 1927 the average clean fruit at picking time in a crop of 378, 554 bushels was 80.8%. In 1928 the average clean fruit in a crop of 309, 499 bushels was 81.1%. Of course there were individuals, and large producers too, that reached more than 95% clean fruit but there were others that were not as successful and the average consequently stood at the point mentioned. The small increase in average clean fruit at picking time in 1928 may be attributed mainly to the fear of arsenical residue.