Mean Berry Weight Research Articles

The relationship between populations of European tarnished plant bug ( Lygus rugulipennis) and crop losses due to fruit malformation in everbearer strawberries

Field experiments in SE England in 1997–1999 were used to determine strawberry crop losses due to the European tarnished plant bug, Lygus rugulipennis. Feeding by the pest on flowers and developing fruits caused malformation of fruits at harvest. A range of pest population densities were generated by different insecticide spray programmes on replicated plots. Relative pest populations were estimated by sampling 40 plants per plot with a beating tray. This method of sampling was shown to have a similar efficiency to suction sampling. A positive correlation was found between the percentage of fruit with moderate or severe malformation and the number of adults plus nymphs of L. rugulipennis. The mean berry weight was also significantly lower in plots with high L. rugulipennis numbers at some sampling dates. A regression analysis of the percentage of moderately and severely malformed fruit against the number of L. rugulipennis was highly significant ( P< 0.001, adjusted R 2=0.34) and had a slope of 0.55, i.e. two Lygus bugs in a beat sample from 40 plants caused approximately 1% of fruits to be malformed. Based on the value of the crop, the cost of insecticide treatment and allowing a safe margin of error, a simple economic spray threshold of one L. rugulipennis per 40 plants is suggested.

Effect of Calcium and Boron Sprays on Yield and Quality of “Elsanta” Strawberry

The aim of the experiment was to examine the effects of foliar applications of calcium (Ca) and boron (B) on yield and fruit quality of “Elsanta” strawberries grown on a sandy loam soil with low status of available B. The study was conducted in 1999–2000 at a commercial strawberry plantation in Central Poland. Cold‐stored strawberries were planted in 1998 at a spacing of 0.25 × 0.8 m. The following treatments were applied: (i) five sprays of Ca as CaCl2 at a rate of 1.5 kg Ca ha−1 spray−1 with addition of Tween 20 adjuvant at 0.1%; the first spray was performed at the petal fall stage and the next at 5‐day intervals; (ii) three sprays of B as Borvit material at a rate of 160 g B ha−1 spray−1 at the beginning of flowering and 5, and 10 days later; (iii) sprays of B and Ca as in the combination of (i) and (ii). Plants sprayed with water served as the control. Results showed that fruit and leaves from Ca‐treated plants had increased Ca concentrations. Sprays with B increased status of this microelement in fruit and leaf tissues. Treatments did not affect total and marketable fruit yield, mean berry weight, the number deformed fruit, soluble solids concentration and titratable acidity of fruit at harvest. Fruit sprayed with Ca or B plus Ca were firmer and more resistant to Botrytis rot at harvest and after 3 days of holding at 18°C compared to those of control plots. Moreover, sprays of Ca or B plus Ca increased soluble solids concentration and titratable acidity of fruit after 3 days of holding at room temperature. These results indicate that sprays of CaCl2 with addition of Tween 20 should be recommended to improve quality and shelf‐life of strawberry fruit, particularly in proecological production where application of fungicides is restricted.

Rootstock and salinity effects on rates of berry maturation, ion accumulation and colour development in Shiraz grapes

Shiraz grapevines on either their own roots, or on the rootstocks Ramsey, 1103 Paulsen, 140 Ruggeri or 101-14, were grown at two separate sites within the Murray-Darling viticultural region with similar irrigation regimes but with an irrigation water salinity of either 0.43 dS/m (low salinity site) or 2.3 dS/m (high salinity site). Rootstock effects on grape berry development, ion concentrations, soluble solids and acidity were followed during one season. Wines were also made and compared using spectral analysis and sensory evaluation. Rootstock effects that were common across both sites were (1) a close relationship between K+ and soluble solids accumulation in developing grape berries which commenced at the onset of veraison and was indicative of a link between K+ and sucrose transport in the phloem, and (2), higher wine K+, pH and colour hue for all rootstocks with one exception, namely 101-14 at high salinity where 101-14 responded similarly to own roots. Juice K+, pH and loss of K+ from juice during winemaking were highest for grapes from the high salinity site. Mean berry weight was smaller and the range in berry size across rootstocks was narrower at the saline site. The narrower range in berry sizes may have contributed to fewer rootstock effects on wine spectral characteristics at high salinity. There was no effect of rootstock on CO2 assimilation rate or stomatal conductance at either site, although intrinsic leaf-based water-use efficiency measured as A/g was 50% higher at the saline site. All treatments exhibited berry shrivel at maturity, but the extent was smaller at high salinity. Slower development of berry colour during veraison was observed on some rootstocks, for example 101-14, and while unrelated to canopy size per se, a higher leaf-to-fruit ratio for 101-14 may have been a factor. Slower berry colour development during veraison had no bearing on the colour density of wine made from the harvested grapes.

Foliar Boron Sprays Do Not Affect Highbush Blueberry Productivity

Abstract Mature 'Jersey' and 'Bluecrop' highbush blueberries (Vaccinium corymbosum L.) received either no boron (B), low B (125 to 250 mg B/liter) or high B (250 to 500 mg B/liter) in multiple foliar sprays over six years to determine if bushes containing relatively low leaf B levels would respond to B supplements. Sprays supplied B at an average annual rate of 0.17 kg B/ha (Low B) or 0.34 kg B (High B). Average leaf B levels over the six years were 16.0 ppm B (control), 21.6 ppm (Low B), and 27.3 ppm (High B). Treatments had no effect on yields or mean berry weight in any year, indicating that leaf B levels above about 15 ppm are sufficient for these varieties.

The effects of fertilizer rate on vegetative growth, yield and fruit quality, with special respect to pigments, in black chokeberry ( Aronia melanocarpa) cv. `Viking'

The effect of fertilizer rate on fruit quality parameters in the black chokeberry ( Aronia melanocarpa [Michx] Ell.) cv. `Viking' was studied over three years. A combined N–P–K fertilizer was applied in different rates. Plant height, yield, berry weight, anthocyanin content, content of brown compounds, content of soluble solids, anthocyanin composition and total acidity were recorded for the different treatments. Increased application of fertilizers resulted in increased vegetative growth and yield whereas the content of anthocyanins and total acidity decreased. Mean berry weight, content of brown compounds, soluble solids and anthocyanin composition were unaffected. Correlations between the different parameters were calculated at single plant level. Positive correlations were found between plant height and yield, between plant height and browning index, and between anthocyanin content and total acidity. Negative correlations were found between plant height on one hand, and anthocyanin content and total acidity on the other hand. It was concluded that an increased fertilizer application results in increased growth and higher yield whereas pigment content and total acidity decrease. Maximum production of anthocyanins per plant was obtained with a medium high fertilizer rate (50 kg N/ha, 44 kg P/ha, 100 kg K/ha).

Changes in fruit quality in black chokeberry (Aronia melanocarpa) during maturation

SummaryBlack chokeberry fruits are rich in anthocyanins and can be used as a raw material for the production of natural food colourants. Fruit quality was studied during maturation in three true black chokeberry cultivars and in three cultivars derived through hybridization between chokeberry and rowans (Sorbus spp.). For each trait studied, the three black chokeberry cultivars were very similar. The three hybrid cultivars differed however from the black chokeberry cultivars for some traits in both timing and size of the response which indicates that cultivar selection for improvement of fruit quality can hardly be done among the true black chokeberry genotypes but may be efficient when the hybrid cultivars are also included. For the black chokeberry cultivars, maximum berry weight was reached already by the 22 August. Anthocyanin content increased by 180% during the period mid-August to mid-September. Meanwhile, the content of undesirable brown compounds increased by 100%. The content of malic acid remained unchanged whereas total acidity decreased in the initial part of the study period. Variation among sampling dates in total acidity was negatively correlated with variation in berry weight which suggests that dilution by water uptake affects total acidity. For the true black chokeberry cultivars, optimal harvest date was determined to be 8 September for this trial, when both mean berry weight and anthocyanin content had reached their maximum. By harvesting one week earlier browning was reduced by 32% but with a simultaneous decrease in anthocyanin content of 20%.

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

SummaryThe 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.

Effects of gypsum on yield and nutrient status of native lowbush blueberry

Information is required on the response of native lowbush blueberry (Vaccinium angustifolium Ait.) to soil-applied calcium amendments. Field experiments were carried out in Prince Edward Island to determine the effects of applied gypsum, as a Ca source, on yield and leaf nutrient content of native lowbush blueberry at six sites, two locations per year. Sites were studied over several cropping cycles. Gypsum applied at 2, 4, 6, and 8 t ha−1 in the spring of the sprout year increased marketable yield (from 3.2 to 4.7 t ha−1) at three of six sites in the first crop year following application of gypsum. Averaged over these three sites, marketable yield was increased 47% by the application of gypsum at 4.0 t ha−1. Yield was not affected in the second and third cropping cycles. Mean berry weight and plant growth were not affected by gypsum application. Concentration of leaf Ca was increased but not consistently significant, while leaf S was significantly increased at all sites in the first cropping cycle. Soil pH was significantly reduced by gypsum in the first cropping cycle. A yield increase of 225 kg ha−1 would be sufficient to recover the costs of the applied gypsum. Key words: Gypsum, leaf nutrient concentration, lowbush blueberry, Vaccinium angustifolium Ait., yield

Shading Timing and Intensity Influences Fruit Set and Yield in Cranberry

Cranberry (Vaccinium macrocarpon Ait.) vines were shaded with either 72% or 93% shadecloth (28% or 7% of full sun) for 1 month before flowering, after flowering, or before harvest. Fruit set was reduced by heavy shade (93%) before flowering in 1991 but not in 1992 or 1993. Heavy shade following flowering reduced fruit set in 1991 and 1992 but not 1993. The number of flowers per upright was generally not affected by shading but was reduced by prebloom shading at either level in 1993. Mean berry weight was usually conserved. Yield was reduced by shading at either level following flowering in 1991 and 1992. Shading just before harvest had no effect on the characteristics measured. Total nonstructural carbohydrate concentration was reduced to about half relative to the controls by either shading level at all treatment dates. Carbohydrate concentrations recovered to control levels by 4 to 8 weeks following removal of shading. Shading always reduced carbohydrate concentrations but did not always reduce fruit set or yield.

Relation between berry weight, number of seeds per berry and 100-seed weight in potato inflorescences

In three potato cultivars, Solanum tuberosum L. ‘Atzimba’, ‘R-128.6’ and ‘Serrana’, the effect of the position of the flower in the inflorescence on berry weight, number of seeds per berry and 100-seed weight was analysed. Mean berry weight, number of seeds per berry and 100-seed weight decreased from proximal to distal flower position, except the 100-seed weight of ‘Serrana’. The relation between berry weight and number of seeds per berry was positive and highly significant. The relationships between 100-seed weight and number of seeds, and between 100-seed weight and berry weight were weak and not consistent for all cultivars. Within and between flower position correlations are illustrated and discussed. In ‘Atzimba’ and ‘R-128.6’, pollination of flowers or harvesting berries from proximal positions only could improve average 100-seed weight.

NEW LEAVES ARE THE PRIMARY SOURCE OF RESOURCES FOR FRUIT SET IN CRANBERRY

The sources of carbohydrate and other resources for fruit growth in cranberry (Vaccinium macrocarpon Ait.) can be spatially partitioned into new growth, old leaves, and woody stems or other adjoining uprights. This research was conducted to determine which spatial source of resources was most important for fruit set in cranberry. At fruit set in late June, we removed the current season growth, one year old and older leaves, or both from 50 uprights per treatment plus a control at two locations. At harvest, fruit set, fruit number and size were determined. In all cases, removing the current season's growth significantly decreased fruit set. Removing both the current season's growth and old leaves produced an additional reduction in fruit set. Removing only old leaves reduced fruit set at one location but not the other. Fruit length, diameter or mean berry weight was not reduced by any treatment. The response of cranberry to resource limitation apparently is to reduce fruit numbers rather than fruit size. This research suggests that current season growth is the primary source of carbohydrates for fruit set in cranberry and that once the fruit are set they have sufficient sink strength to attract resources from a distance.

Effect of sawdust mulch on yields of select clones of lowbush blueberry

The effect of sawdust mulch applied at 0-, 5- and 10-cm depths on yield of select clones of lowbush blueberry (Vaccinium angustifolium Ait.) was studied in Prince Edward Island for three consecutive cropping cycles from 1985 to 1989. Sawdust applied post-plant, as a mulch, at a depth of 5 cm increased the total yield of the first three harvests by approximately 30% compared to the 0-cm mulch. Mean berry weight was also increased where sawdust was applied. There was not significant difference in yield between the 0- and 10-cm sawdust application treatments. The 10-cm sawdust mulch reduced plant survival by 23% compared with the check. Key words: Lowbush blueberry, Vaccinium angustifolium Ait., select clone, sawdust mulch, yield

Influence of Leaf Area on Fruit Development and Quality of Italia Glasshouse Table Grapes

Restricting the leaf area providing photosynthates for each grape cluster reduced mean cluster weight through a reduction in mean berry weight. Berries from plants with reduced leaf area grew more slowly and never reached the size of berries from plants with higher leaf areas. Time taken to reach maturity (16° Brix) was also affected as plant leaf area decreased; accumulation of sugars and reduction in titratable acidity were retarded. Over one month9s difference in picking date was recorded between the two extreme treatments. In this experiment, Italia grapes required between 7.2 cm² and 9.5 cm² of leaf area per gram of fruit to promote optimal ripening.

Evaluation of row spacings and support systems for autumn-fruiting raspberries

Abstract The effects of three inter-row spacings (3 m, 1.5 m, and 0.75 m), and two support systems (training vertically or on a V-shaped trellis) on total yield, yield components, and ease of hand picking of autumn rasperries (Rubus idaeus L. ‘Heritage’) was investigated in a 3-year field trial in Canterbury. In the first year, number of fruiting canes/m2 and yields/ha were both increased as row spacings were reduced from 3 to 0.75 m. However, in the second and third seasons, although these parameters were increased as spacings were reduced from 3 to 1.5 m, a further reduction in spacing to 0.75 m had no effect. Neither the number of berries per fruiting cane nor yield per fruiting cane were significantly affected by row spacings, although there was a tendency for mean berry weight to increase as row spacing was reduced. Reducing row spacing from 1.5 to 0.75 m made access to rows difficult and reduced picking rate. Training canes on a V trellis had no significant effect on any of the measured parameters a...

INFLUENCE OF FOLIAR-APPLIED N-P-K FERTILIZERS ON PRODUCTIVITY AND NUTRITION OF JUNE-BEARING STRAWBERRIES

A 2-yr field experiment was conducted to determine the influence of supplemental N-P-K foliar fertilizers (9-8-7 or 16-2-3) applied during flowering, fruit enlargement and/or flower initiation on yield, quality, and nutrition of Earliglow strawberries (Fragaria × ananassa Duch.). All plots received soil applied fertilizer at planting and at renovation according to soil test recommendations. Foliar fertilizers did not significantly increase total yield at any of the rates or times of application employed. Average yields the first year were 1.5 times greater than those the second year, regardless of whether foliar fertilizers were applied. Treatments did not significantly affect mean berry weight or percent soluble solids. Concentrations of N and P in recently matured leaves sampled during harvest were not significantly affected by foliar treatments, but K level was increased in the second year of the study by some foliar treatments.Key words: Fragaria spp., foliar nutrient sprays, nitrogen, phosphorus, potassium, strawberry

Boysenberry: Factors influencing efficiency of machine harvesting

Abstract Boysenberries were machine harvested for two consecutive seasons using a fingerdrum harvester. In the second season a ‘Littau’ (beater) harvester was also used. Yield losses always occurred when plots were mechanically harvested; saleable yield was 51–66% that of handpicked plots. The major source of yield loss was fruit loss to the ground during harvest. The lower mean berry weight of machine harvested fruit, removal of immature fruit, and breakage of fruiting laterals resulted in much smaller losses. We were unable to account for some of the yield loss. Quality of harvested produce was influenced by the harvester type used and temperature at harvest. Fruit harvested by the fingerdrum machine were always more acidic than fruit harvested by the Littau or by hand. Handpicked fruit were firmer than machine harvested fruit only when harvesting was done during the cooler part of the day. Delaying the time of first harvest until 60% of fruit were visually ripe did not significantly reduce saleable yie...

The relationship between two-spotted spider mite and strawberry yield in Canterbury

Abstract Strawberry (cv. ‘Red Gauntlet’) yield was measured over two growing seasons, 1984 — 85 and 1985 — 86, in field experiments with a series of treatments involving two-spotted spider mite (TSSM) (Tetranychus urticae Koch), exclusion of predators and pesticide application. Two-spotted spider mite populations were much higher on first season plants than on older plants. Insecticides and miticides apparently play an important role in TSSM population regulation in first season plants but natural population regulation may be more important in populations on older plants. In their first season, plants yielded significantly less than second season plants, although mean berry weight was similar. The yield variation in plants of different ages cannot solely be attributable to seasonal affects. High, uncontrolled TSSM infestations in one season reduced yield in the following season but in the second season the yield variation between newly planted and established plants was still evident. Mite levels on established plants may not attain yield-reducing levels in Canterbury. Poor yields from new plantings may be due to treatment received by mother plants before runner lifting.

Red raspberry cv. Skeena: Influence of frequency of machine harvesting on fruit yield and quality

Abstract The effect of the frequency of machine harvesting on the yield of red raspberry (Rubus idaeus L. cv. Skeena) was investigated using a finger-drum harvester. Yields from machine-harvested plots were compared with those from carefully hand-harvested plots to determine machine efficiency. With a 2-day harvest interval, 68% of potential yield was recovered by the machine. Increasing the interval between harvests to 4 or 6 days significantly reduced yield. Major sources of yield loss were fruit loss to the ground during harvest, green fruit removal — either individually or attached to laterals broken by the machine — and lower mean berry weight of machine-harvested fruit. Machine-harvested fruit was riper (lower in acidity) than handpicked fruit.

Preliminary studies on mechanical harvesting of boysenberries

Abstract The yield obtained from boysenberries harvested by a beater-type mechanical harvester was 55% of the potential yield measured by hand harvesting. The major factors contributing to this difference were the lower mean berry weight of fruit harvested by machine, lateral breakage during passage of the machine, and fruit loss between or during passes of the machine. Saleable yield was similar, irrespective of whether the crop was first harvested when 10, 20, or 40% of the berries were visually ripe. Yield was substantially reduced when the crop was harvested once, rather than twice, a week. Mechanically harvested fruit was more mature (i.e., higher in anthocyanins, soluble solids, and carbohydrates, and lower in acids) than handpicked fruit. This explained the delayed rise in the cumulative yield from mechanically harvested plots. The time of picking of each fruit was affected by its position on the lateral. On average, the terminal fruit on the lateral was picked first and the fifth fruit last.

Yield Component Analysis of ‘Benton’ and OR-US 4356 Strawberries

Abstract In the 1st (1981) and 2nd (1982) fruiting years, ‘Benton’ strawberry (Fragaria x ananassa Duch.) formed 25% to 30% more crowns/plant than the advanced breeding selection OR-US 4356. ‘Benton’ had fewer trusses/crown than OR-US 4356 in 1981 (0.93 vs. 1.47) but both had 1.5 in 1982. OR-US 4356 had about 60% more fruit/truss in each season; however, ‘Benton’ had 75% greater mean berry weight than OR-US 4356, so that the 2 genotypes produced essentially the same yields/plant in each season, averaging 0.82 kg (1981) and 0.94 kg (1982). The genotypes did not differ in the total number of achenes/berry. Both showed a linear increase in berry weight with achenes/berry; yet OR-US 4356 had significantly lower berry weight than ‘Benton’ at equivalent achenes/berry. Increased berry expansion in ‘Benton’ was reflected by a reduction in number of achenes/cm2 of berry surface. The values, averaged over both seasons, were 10.6 (‘Benton’) and 14.0 (OR-US 4356). OR-US 4356 failed to produce higher yields than ‘Benton’ because of limitation in fruit expansion.