Strawberry fruit yield and quality responses to flower bud removal: A simulation of damage by strawberry blossom weevil (Anthonomus rubi)

Summary

The effect of flower bud severing (with scissors) on the yield and fruit quality of strawberry (cv. Elsanta) grown on raised, polythene-mulched beds varied with plant size and numbers of flower buds per plant. On very small plants (with an average of seven flower buds and yielding 105 g of fruit per plant) severing reduced yield in direct proportion to the proportion of flower buds severed, irrespective of whether severing included or did not include removal of the primary (first node) flower bud. There was no evidence of crop compensation. On larger plants (with 24, 70 and 117 flower buds and yielding 0.34 kg, 0.73 kg and 1.16 kg of fruit per plant respectively) severing up to 12 buds per plant did not significantly affect yield: mean berry weight increased by up to 11% and the percentage fruit (by number) in quality class I increased from 67% to 72% in response to severing. Two mechanisms of yield compensation were, apparent i) an increase in mean berry weight, and ii) the maturing of alternative replacement flower buds. Severing slightly delayed by 1–2 d the date by when 10% and 25% of fruit was picked. Implications for the economic damage threshold for flower bud severing by the strawberry blossom weevil are discussed.     

Effect of Pruning and Partial Disbudding on the Cropping of Comice and Beurré Hardy Pears

The effects of three intensities of pruning on fruit set, fruit bud development, cropping and vigour of intensively grown Cornice and Beurré Hardy pears were compared over a three-year period. Severe pruning, in which extension shoots were cut back to fruit buds on the two-year-old wood, greatly increased the set of fruits per 100 flower clusters and reduced vigour, in comparison with a renewal type of pruning. Severe pruning of Comice caused a relative reduction in the number of fruit buds in subsequent years, so the improvement in fruit set did not lead to an increase in crop per tree, but with Beurré Hardy fruit bud formation was unaffected and the crop per tree was increased by hard pruning. There was an improvement in yield in relation to tree size with both varieties. Pruning to fruit buds provides a means of increasing yields per acre by ‘containing’ pear trees at close spacings without reducing the yield per tree.

Partial disbudding just before blossoming increased fruit set but not enough to offset the reduction in number of fruit buds. Supplementary pollination did not improve the yields of Comice and increased the crop of Hardy in one year only.     

单株留芽量及结果母枝剪留长度对猕猴桃结果性能的影响

对栽植株行距3m×4m的美味猕猴桃秦美品种连续进行了3年试验,单株分别剪留250、300、350、400个芽处理后,平均单株新梢数、叶面积指数、落叶率与留芽数量呈正相关,叶幕下层的光强度、净光合率与留芽数量呈负相关;单株果枝数、果实数及单位面积产量均以留400芽处理最高,但平均单果重最小,88g以上的优质果产量最低。综合评价以单株剪留350个有效芽的效果最佳,优级果产量达到2102.7kg/666.7m2。结果母枝分别剪留7、12、17个有效芽处理后,平均每母枝的结果枝数、果实数、产量与留芽数量呈正相关,均以17芽处理最高,分别达到9.5个、30.4个和3.09kg,各处理间的单果重差异不显著。     

The components of yield in black currants

Examination of black currant data relating berry weight, seed number and position on the raceme indicates that there is an upper limit of berry weight (potential weight) for each position on the raceme. This limit may be a genetic character of the cultivar.A suitable combination of seed number and rate of development is necessary to reach potential berry weight and berries may be sub-maximal from deficiency in either or both factors arising from different causes.Berries seem to develop within a range of potential sizes so that differences in numbers of berries do not affect the mean size.Crop yields can be related to 5 variable components affecting fruit number and to 2 affecting fruit size, apart from the possible genetic limit. Of these components 5 operate in the pre-fruiting year ending with the termination of flower initiation, and 2 affect performance in the fruiting year.Partitioning the shortfall in numbers and size to the variable components can direct attention to deficiencies in particular phases of development causing reduced yields.     

Contributions of short- and long-shoots to yield of ‘Kerman’ pistachio (Pistacia vera L.)

The canopy of a mature ‘Kerman’ pistachio (Pistacia vera L.) tree is composed of two types of shoots: short-shoots composed entirely of preformed nodes, and long-shoots composed of both preformed and neoformed nodes. Since the production of these two types of shoots is known to be related to rootstock and rootstock influences yield of pistachio the relationship of these two types of shoots to yield was investigated during two cropping years. Individual short-shoots produced significantly less yield and had fewer fruit clusters per shoot compared with long-shoots, but collectively produced 55–60% of the total yield. Long-shoots positively affected yield components in one year, but had no effect in the other year. Whether the differences in the one year were due to canopy position and light interception or differences in the carbohydrate allocation within the two types of shoots could not be determined from the current data. Long-shoots initiated more inflorescence buds, although inflorescence bud formation was restricted to the preformed growth and only the 3–4 earliest neoformed nodes. However, when expressed as a percentage, long-shoots retained a lower percentage of initiated inflorescence buds, compared with short-shoots. Regardless of shoot type, less than half of the retained inflorescence buds produced mature fruit clusters. Thus, inflorescence bud retention, a previously hypothesized mechanism of pistachio alternate bearing, may not be the primary limiting factor to yield in pistachio.     

Vegetative and yield component characteristics of micropropagated muscadine grape (Vitis rotundifolia Michx.)

SUMMARY

Evaluations were made of the field performance of micropropagated (tissue cultured axillary buds) versus conventionally rooted softwood cuttings of muscadine grape, Vitis rotundifolia Michx. Trunk cross-sectional area did not differ between treatments during three years of field evaluation following planting. There were no differences in leaf area and dry weight or shoot number in the two propagation types; leaf morphology was normal with no apparent juvenile characteristics. Yield components including flower number per shoot and inflorescence, fruit number, total fruit weight and yield efficiency were greater in micropropagated plants during the second year, the first year of cropping; differences diminished and yield components were not different in year three. Performance of tissue cultured plants was therefore as good as, or surpassed, conventionally propagated plants during early vine establishment.     

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.     

The influence of yield components on cultivar differences in black currants

The potential and actual yields per bush evaluated in 14 black currant cultivars were shown to result from the interaction of 8 yield components. Of these, 4 developed in the pre-fruiting year and 4 in the fruiting year.By relating berry size to position on the raceme and to seed content, potential yields were calculated, and the shortfall in actual yield partitioned between 3 causes of loss: missing berries, insufficient seeds and poor berry development.It is suggested that the upper limit of berry size for each position on the raceme is determined genetically.From comparisons of plant performance it was concluded that yield differences are related more to a potential created in the pre-fruiting year than to differences arising during the fruiting-year.     

Biennial bearing in apple and pear: A literature survey

Fruit growers do not want biennial bearing which is an old problem in fruit growing. Although the problem is less urgent with modern cultivars and cultural techniques, it is still there. In particular, some cultivars of high fruit quality, which have a biennial bearing habit, are a challenge to modern growers. The formation of fruit buds is the central problem, which may be influenced by a number of factors such as, e.g., fruit set and fruit growth, type of branch, rootstock, pruning and growth regulators. By deflowering halves of trees, it is possible to have at least halves of a crop each year and this seems a practical solution for home gardens, although one does not obtain a full crop. The best prospects are for the use of growth regulators which can promote fruit bud formation in an “on-year” and reduce it in an “off-year”. These might be used after thinning of an excess of fruits or even when no thinning has taken place.     

Soil pH effects on yield and fruit size of two rabbiteye blueberry cultivars

The effects of soil pH on yield and average berry weight of rabbiteye blueberry cvs Delite and Tifblue were investigated. Over a three year period, the higher soil pH decreased from 6.5 to 5.9, but the total yield of both cultivars decreased more than 60% as soil pH increased from 4.5 to 6.5 in the first two years and to 5.9 during the last year. Percent marketable yield was less influenced by the change in soil pH than was total yield. ‘Tifblue’ produced more fruit and had higher marketable yields, but the fruit size determined by average berry weight was smaller than ‘Delite’. When the soil pH was at a more desirable range for maximum yield (4.5 to 5.3), ripening was more uniform for both cultivars. This study illustrated that: (a) two rabbiteye blueberry cultivars differed in tolerance to alkaline growing conditions, (b) the response of the two cultivars to the change in soil pH varied from year to year, and (c) total yield of both cultivars was maximized when soil pH was below 5.0.     

Fruit set is inversely related to flower and fruit weight in olive (Olea europaea L.)

Fruit weight is strongly correlated to ovary weight in olive as big-fruited cultivars have larger ovaries and flowers at bloom. We tested the hypothesis that larger ovaries imply stronger sinks and therefore reduce fruit set, expressed as number of fruits. Flower/fruit load per centimeter of shoot was assessed every month from flowering to harvest, on sample shoots of many different olive cultivars differing in fruit size. Data were taken for two years: 2007 and 2008. Additionally, in 2008, a fruit thinning experiment was carried out by leaving a single fruit per shoot, to assess the maximum potential fruit weight achievable by each cultivar. Results indicated that fruit size was mostly genetically determined as thinned fruits of small-fruited cultivars, although bigger than control fruits, never got as big as fruits from large-fruited cultivars, confirming that large ovaries are a prerequisite for large fruits. Among all cultivars, the number of flowers per inflorescence, the number of inflorescences, and the number of flowers per centimeter of shoot were not correlated to average flower weight while total flower mass per centimeter of shoot was positively correlated to average flower weight (i.e. large flowered/fruited cultivars had greater total flower mass). However, one month after bloom and thereafter, all parameters were negatively and exponentially correlated with fruit average weight across cultivars, except fruit mass per centimeter of shoot which was generally not correlated to fruit average weight, except in one year, at harvest, when fruit mass per centimeter of shoot was positively correlated to fruit average weight. These results suggest that fruit set is a consequence of, and inversely proportional to flower/fruit size in olive.     

Productivity of individual cranberry uprights in Washington and British Columbia

Yield-component partitioning of the individual cranberry upright (fruiting shoot) was undertaken using a model which included upright length, number of leaves, flowers, berries and seeds, and fruit weight. Repeat cropping of the upright during the following year was also modelled and tested. Fruit set was a major component of yield, but its action was sometimes indirect. Less important components were the number of seeds per berry, berry enlargement per seed, and upright length. Measures of antagonism of “fruiting” to floral initiation were obtained which partially explain the biennial bearing habit of uprights.     

Effect of part-tree flower thinning on fruiting,vegetative growth and leaf photosynthesis in ‘Cox’s Orange Pippin’ apple

Flower clusters were removed at full bloom from ten year old ‘Cox’s Orange Pippin’ trees on M.9 rootstocks, over the whole tree, on alternate branches or on whole sides. Mean fruit weight per tree at harvest was linearly dependent on leaf area per fruit and on light interception per fruit, both relationships accounting for over 90% of the variance. These relationships did not differ between treatments, implying either a mobile pool of carbohydrate or photosynthetic adjustment within the tree to crop load. Measurements of leaf photosynthesis in July and September showed no statistically significant differences in photosynthetic rate of spur or extension shoot leaves on bearing or non-bearing branches. Although the treatments caused no overall effects on shoot growth or leaf area per tree, sides of trees without fruit had greater leaf area and shoot growth than did sides bearing fruit. Fruit mineral composition and percentage dry weight were not affected by treatment except where the treatments significantly altered fruit size. In the following spring, although the treatments did not affect the total number of flower buds produced, branches that were deflowered in the previous spring carried significantly more flower buds than did branches which had cropped.     

Initial Crown Diameter of Transplants Influences Marketable Yield Components of Two Strawberry Cultivars in Annual Hill Production System

Abstract

Influence of initial transplant size on yield components was investigated using two strawberry cultivars over a three-year period. Plants were sorted into three groups according to crown size each fall before transplanting.

Fruits were harvested once a week over a ten-week period each year. There were marked differences between ‘Chandler’ and ‘Camarosa’ cultivars. Transplants of the ‘Chandler’ cultivar with larger crown diameters produced significantly greater early and total marketable yield than transplants with smaller crown diameters. Regression analysis of yield components against initial crown diameter revealed a positive relationship between total fruit numbers produced per plant and initial crown size for both cultivars. Total weight of marketable fruit produced per plant was positively associated with initial crown diameter of transplants. Relationships between initial crown diameter and early yield components were not as consistent among the two cultivars tested. Early yield components of ‘Chandler’ were all correlated to initial crown diameter of transplants. The size of the transplant did not influence early yield components of ‘Camarosa’ except for fruit size. There was a significant relationship between the postharvest dry weight of plants and initial crown diameter of transplants.     

Potential of ethephon,NAA, NAD and urea for thinning pistachio fruitlets

Alternate bearing, the occurrence of high yield ‘on’ year followed by low yield ‘off’ year, is striking in pistachio (Pistacia vera L.). Floral buds of pistachio are formed a year before bloom, but abscise during the years with heavy crop (‘on’ year). Abscission of floral buds is due to competition between growing seeds on 1-year-old shoots and developing buds on current season growth. We studied the effects of chemical fruit thinning on alternate bearing and nut characteristics in a commercial orchard of ‘Owhadi’ pistachio cultivar during 2003–2004 in Rafsanjan, Iran. In both years, ethephon (100 and 200 mg l⁻¹), naphthaleneacetic acid (NAA) (125 and 250 mg l⁻¹) and urea (2.5 and 5%) were applied to the branch units of each individual ‘on’-year trees. The results showed that ethephon at both concentrations significantly increased fruit thinning and floral bud retention for the subsequent year. Other treatments also increased fruit thinning and floral bud retention but were inferior to ethephon.     

The components of fruit size in strawberry

High Correlation coefficients have been found in the application of the formula:

$\text{Fresh weight of ripe berry}\text{(g)}\text{=}\text{(Total number of achenes?C)F}\text{(Number of achenes per cm}{}^2\text{of surface}$

to data for a large number of strawberries from nine cultivars. Of the terms in the equation (Total no. of achenes — C) was found to be different in different cultivars and to be related to the position of the berry on the inflorescence, but there was no constant relationship between the achene numbers in the different ranks of berry. Whether the numbers of achenes per berry can be altered by environmental or cultural treatments was not resolved. F, a term having the dimensions of weight per area, represents weight per unit area of berry surface and seems to be constant amongst plants of a cultivar subject to uniform treatment, but differs between cultivars and treatments.The number of achenes per cm² of surface on ripe berries is a measure of berry development in the fruiting season and may be affected by environmental and managerial factors and by internal competition between fruits and leaves on the same plant.The interactions of these factors on berry size enable two stages to be recognised at which size is determined, namely during flower formation, when achene numbers and possibly F are fixed, and during fruit development after pollination when the term for spatial distribution of achenes is settled.It is suggested that an examination of the effects of different treatments on each of the size components might enable a distinction to be drawn between the influence on yield of genetic characteristics on the one hand and intrinsically variable characteristics subject to external influence on the other hand, thus clarifying the type of research and/or development needed to enable growers to achieve maximum yields.     

Plant spacing and cultivar affect melon growth and yield components

The objective of this study was to evaluate the effect of cultivars and in-row spacing on vegetative growth and yield components in melon (Cucumis melo L.). The cultivars ‘Early Dawn’ (ED), ‘Superstar’ (SS) and ‘Medoro’ (ME) were grown in rows 1.5 m apart at plant spacing 0.6, 0.9, 1.2 or 1.5 m. Cultivars ED and SS were grown in 1998 and 1999, while ED and ME were tested in 2000. The main vine length, diameter, number of leaves and lateral branches were highest at 1.5 m in-row spacing in 1999 and 2000, while there was no influence of plant spacing on observed growth parameters in 1998. ED performed better compared with other two varieties, mostly due to more fruit per ha and per plant. Yield was significantly decreased with increased plant spacing in all 3 years of research. At in-row spacing of 1.5 m yield was in average 25% lower than at 0.6 m spacing. Average fruit weight slightly increased with plant spacing up to 1.2 m, even though the differences were significant only in 1999. Small differences among cultivars were also found. Number of fruit per ha decreased linearly while number of fruit per plant increased linearly as plant spacing increased in all cultivars except SS in 1999.     

Optimum leaf area index in T-bar trained kiwifruit vines

Summary

The effect of leaf area index (LAI) on canopy growth, light interception, yield, fruit growth and quality and return bloom of kiwifruit were examined in 1990 and 1991. Different LAIs were obtained in the 1990 season with defoliation treatment made precociously at different intensities, in a diffuse way, uniformly in the whole canopy. At the end of canopy development LAIs of 3.6,3.3,3.1,2.6 and 1.8 were obtained and evaluated. The kiwifruit vines with a bud load of 680?700 and LAIs of 3.3 and 3.6 in 1990, showed an optimum and constant yield (>90 kg per vine), good average fruit weight (>100 g) and high fruit quality in both years, and also good return bloom the following season. The reduction of LAI to 2.6 and 1.8 drastically reduced, in the year of LAI imposition, both yield (?18.5% and ?30%, respectively) and mean fruit weight (?18.6% and ?29.1%, respectively) compared with vines with an LAI higher than 3.1. In the same treatments, the soluble solids concentration in the fruit was significantly decreased and a great reduction in numbers of fruiting shoots and numbers of fruits per fruiting shoot were observed in the year following the LAI imposition. In vines with the same bud load, fruit number and an LAI of 3.1, small variations in yield and fruit weight in the year of defoliation treatments were recorded, but in the following season the yield was significantly reduced (?14 kg per vine) due mainly to a decrease in the number of fruiting shoots (?14%). In kiwifruit vines with low LAI (2.6 and 1.8) nearly all fruits present in the canopy ripen, with no significant fruit drop. At low LAI, the sink strength of the fruit was greater and more extended so that vine growth and the plants reserves were restricted. Under the conditions of this experiment, an LAI higher than 3.3, corresponding to a leaf area-fruit ratio higher than 600 cm² per fruit, is necessary to obtain regular vine growth and yield, optimum fruit size and quality and return bloom the following season.     

The Effects of Light Intensity,Day Temperature and Water Supply on the Fruit-Ripening Disorders and Yield of two Varieties of Tomato

A study was made of the effects on fruit-ripening disorders and crop yield of shaded and unshaded glasshouses maintained at both high and low daytime temperatures (80° F. (26 ? 5° C.) and 65° F. (18 ? 3° C.)), in which were grown two varieties of tomatoes (Potentate and Ware Cross) at two levels of watering.

Shading the glasshouses reduced the proportion of non-uniformly coloured fruit at the high temperature. At the low temperature, shading reduced the proportion in i960 but there was no effect in 1959. Light watering reduced the proportion of non-uniformly coloured fruit in the first year but it had little effect in the second year. The variety Ware Cross bore approximately 10% fewer non-uniformly coloured fruit than did Potentate in both years.

Shading the glasshouses reduced yield in both years, the decrease being greater (62%) in the very dull year of i960 than it was (40%) in the very sunny year of 1959. The house at the low day temperature yielded a 30% greater weight of crop than the warmer house. In both years the heavily watered plants yielded more than the lightly watered plants because of an increase in mean fruit size. Potentate and Ware Cross yielded similar weights of crop in both years but Ware Cross bore more fruits and had a smaller mean fruit size.

The gross cash return obtained in 1960 was reduced by shading the glasshouses, by maintaining a high day temperature and by growing the variety Potentate as opposed to Ware Cross. The differences in the watering regimes employed had little effect on the cash return obtained.

By assuming that yield and quality have simple mathematical relations with degree of shading, the profitability of shading is discussed. It is shown that shading is not likely to be profitable.