After Full Bloom Research Articles

Effects of Prohexadione-Ca, Ethephon, and Water Stress on Growth and Productivity of 'Golden Delicious'/M.9 Apple

Prohexadione-calcium (Pro-Ca), ethephon and transient water stress were evaluated in a factorial design, as potential inhibitors of early-season shoot growth of high density orchard management of apple (Malus domestica Borkh.) trees. In the experiment, water stress was imposed to one-half of the 7-year-old 'Golden Delicious'/M.9 apple trees in each of 5 blocks, by stopping irrigation for 3 weeks between 35 and 56 days after full bloom (AFB). Within each whole unit, the following Pro-Ca and ethephon treatments were randomly allocated at <TEX>$2{\times}2$</TEX> factorial: a) 0 or 250 <TEX>$mg{\cdot}L^{-1}$</TEX> a.i. Pro-Ca applied at 28 days AFB and b) 0 or 300 <TEX>$mg{\cdot}L^{-1}$</TEX> a.i. ethephon applied twice (35 and 71 days AFB). All trees were hand thinned to king flowers prior to treatments. Vegetative shoot growth was markedly reduced by Pro-Ca, with its effect being obvious within 14 days after application, while ethephon and water stress treatments were less effective. Pro-Ca had no effect on fruit set and yield but slightly increased fruit size. Ethephon substantially reduced the fruit size and yield but had no effect on fruit set. Water stress reduced fruit set, fruit size and yield. With regard to fruit quality, Pro-Ca did not influence fruit shape, flesh firmness and soluble solids contents (SSC) but slightly reduced titratable acidity. Ethephon had no effect on fruit shape but increased firmness, SSC and acidity, while water stress did not influence these fruit quality attributes. Dry weight of dormant spur buds was reduced by both Pro-Ca and water stress, while increased by ethephon. The larger dormant buds led to the larger spur flowers at the tight cluster stage the following spring. Return flowering was promoted only by ethephon, especially on previous season's shoots. There were no significant interactions between Pro-Ca and ethephon or water stress on most variables observed in this study.

Thinning with NAA, NAD, ethephon, urea and by hand to improve fruit quality of 'Gerdi' apricot

This research was conducted to study the effects of chemical and hand thinning on fruit quality of 'Gerdi' apricot. In the first year, three weeks after full bloom (AFB) branches of mature trees were sprayed with naphthalene acetic acid (NAA) at 10, 20, and 40 mg L-1, naphthalene acetamide (NAD) at 20, 40, and 80 mg L-1, ethephon at 50, 100 and 200 mg L-1, or urea at 0.2, 0.4, and 0.6%. In next year, hand thinning was performed as a separate experiment and leaf to fruit ratio (LFR) was adjusted to 10:1, 20:1 or 30:1 at pit-hardening stage of fruit development. In both years, NAA at 40 mg L-1, NAD at 80 mg L-1 and all concentrations of ethephon significantly increased fruit drop. All concentrations of urea significantly increased fruit drop in 2006, but only the two lower concentrations were effective in 2007. NAA at 20 and 40 mg L-1, and NAD at 40 and 80 mg L-1 increased fruit weight in 2006, but only the highest concentration of NAD was effective in 2007, while urea was effective at all concentrations in both years. Ethephon effect on fruit weight was not significant at all. Hand thinning consistently increased fruit weight, but length and diameter were increased only at a leaf to fruit ratio of 30:1. Hand thinning also increased total soluble solids (TSS), total soluble solids to total acidity ratio (TSS/TA), pit weight and flesh to pit ratio.

Mechanism of seedlessness in Iranian seedless barberry ( Berberis vulgaris L. var. asperma)

Species of barberry ( Berberis vulgaris L. var. asperma) is cultivated in arid and semi arid areas of Iran (South Khorasan province). It is widely used as a food additive. Fruits of this species are seedless, while wild type barberries produce seeds in the same area. In this study, we investigated the mechanism of seedlessness in seedless barberry by pollen viability test, field pollination experiments and microscopic observation of pollen tube growth in pistil and ovule development. For comparison, we also examined ovule development in wild type barberry ( B. crataegina DC). In seedless barberry pollen germination was about 54%. Seedless barberry produced 20% seeded fruits when pollinated with pollen of wild type barberry. There was a sharp decrease in fruit set in emasculated unpollinated flowers of seedless barberry. In seedless barberry, a large number of pollen grains (about 370) were observed on stigma of each flower at 12 h after balloon stage (ABS). Most of them germinated and penetrated intracellular area of stigma surface, but no pollen tube reached ovary. In seedless barberry, many ovules did not have any embryo sac or had a very small incomplete embryo sac. In addition, unfused polar nuclei were clearly recognized in some cases at 14 days after full bloom (AFB). However, in wild type, double fertilization was accompanied by disappearance of polar nuclei. In seeded barberry, the cellularized endosperm became apparent at seven days AFB. At 21 days AFB, all ovules of seedless barberry were degenerated, while at the same time in wild type, one or two ovules of each flower were normal and were developing into complete seeds. Results showed that self-incompatibility has a main role in seedlessness of seedless barberry. However, the high frequency of abnormal ovules and single fertilization can be considered as two other reasons of seedlessness. Due to our results, fruits of seedless barberry were set by stimulative parthenocarpy.

Water deficit-induced changes in mesocarp cellular processes and the relationship between mesocarp and endocarp during olive fruit development

A field experiment was conducted during two consecutive growing seasons to determine and quantify the growth response of the olive (Olea europaea L. cv. Leccino) fruit and of its component tissues to tree water status. Pre-dawn leaf water potential (Psi(w)) and fruit volume were measured at about weekly intervals, and fresh weight (FW) and dry weight (DW) of the fruit tissues at 15, 20 and 21 weeks after full bloom (AFB). Fruit anatomical sections were prepared at 8, 15 and 21 weeks AFB for area determinations and cell counts. Fruit volume of the well-watered trees (average Psi(w) = -0.97 MPa) increased rapidly and reached the greatest final size, that from the most stressed (average Psi(w) = -2.81 MPa) grew most slowly and were smallest. In general, equatorial transverse areas of the mesocarp increased with increasing Psi(w), and this response was more evident at 21 than at 15 weeks AFB. By 21 weeks AFB, the mesocarp of the well-watered trees reached values more than three times higher than those measured at 8 weeks AFB. The endocarp FW and DW did not increase between 15 and 21 weeks AFB. Within each sampling date the endocarp area, FW and DW responded weakly to Psi(w). The mesocarp-to-endocarp ratio (FW and DW) increased from 15 to 21 weeks AFB regardless of water status, mainly due to the mesocarp growth. In both years at 20 and 21 weeks AFB, low values of the mesocarp-to-endocarp ratio were found with Psi(w) below -2.5 MPa. Within the mesocarp, cell size was more responsive to water deficit than to cell number. At 8 weeks AFB, the number of cells in the mesocarp was unaffected by tree water deficit, whereas cell size decreased, although slightly, in fruits sampled from trees in which Psi(w) was < -3.0 MPa. At 21 weeks AFB, cell size showed a linear decrease with increasing level of water deficit, whereas the number of cells at 21 weeks AFB decreased as the Psi(w) decreased below -2.5 MPa and seemed unaffected above that range. Overall, the results clarify the complexity of the water-induced response of mesocarp and endocarp growth and cellular processes of olive fruits.

Olive fruit pulp and pit growth under differing nutrient supply

The objetive of this work was to study if the addition of nutrients to the irrigation water modified ‘Manzanilla de Sevilla’ olive pulp and pit growth. The experiment was carried out during the 2003 fruit-growth period in an irrigated orchard near Seville, southern Spain. Fruit samples were taken in July and September, at 12 and 21 weeks after full bloom (AFB) respectively, in trees irrigated with (T1) or without (T0) the addition of nutrients (N–P–K). The nutrient availability of T1 fruits increased the fruit fresh and dry weight, longitudinal and equatorial diameters, and the pulp-to-pit ratio, characteristics particularly appreciated for table olives. The balance of growth between the fruit mesocarp (pulp) and endocarp (pit) was modified because those two tissues were affected differently. Mesocarp fresh weight was significantly higher at both 12 and 21 weeks AFB in the fertilized treatment, as was mesocarp dry weight at 12 weeks AFB. Neither the endocarp fresh and dry weight nor shape (the ratio of the equatorial and longitudinal diameters) was altered at either of the two studied dates. These results emphasize the importance of an appropriate fertilization management in irrigated olive orchards, particularly for table olives, and also confirm the olive endocarp as a strong sink tissue that competes with the mesocarp during early development.

Fruit Yield and Quality as Related to Flushes of Bearing Shoots in Litchi

The goal of this study was to document the relationship between fruit growth patterns and flushing number in litchi (Litchi chinensis Sonn. cv. 73-S-20). The impact of flush number on fruit retention, fruit quality, and leaf efficiency (g fruit FW produced per unit of leaf area at harvest) was assessed in field-grown 6-year-old trees by adjusting the number of flushes per bearing shoot through girdling at two fruit developmental stages. The cumulative fruit growth was sigmoidal. The greatest fruit relative growth rate (RGR) occurred during 3 to 5 weeks after full bloom (AFB), peaking on week 3 at 0.39 g·g−1 dry weight (DW) per day. The greatest fruit absolute growth rate (AGR) occurred during weeks 8 to 11, peaking on week 11 at 0.16 g·d−1 DW. Fruit retention was sensitive to girdling applied during week 3. Most fruit dropped on branches with ≤ two flushes, whereas fruit continued to develop on branches with three flushes and on the controls. There was a gradual loss of fruit when the girdling was applied during week 8. The number of fruit retained on branches with two and three flushes was similar to the controls. At harvest, regardless of the time of branch girdling, fruit yield and quality increased with increasing number of flushes; shoots with three flushes were similar to ungirdled controls. Leaf efficiency on branches girdled during week 3 was inferior to that girdled during week 8. All treatments had similar leaf efficiency when branches were girdled during week 8. On the other hand, girdling treatment applied during week 3 resulted in variable leaf efficiency among treatment, indicating that fruit were utilizing reserves in bearing shoots. We concluded that bearing shoots of ‘73-S-20’ litchi trees require a minimum number of three flushes for adequate fruit production.

Productivity of olive trees with different water status and crop load

SUMMARYA field experiment was conducted over two growing seasons to determine the combined effect of crop load and irrigation on yield components of olive trees (Olea europaea L. ‘Leccino’) planted at 6 m 3.8 m in a sandy-clay soil. Different crop loads were established by manual thinning of fruits. Drip irrigation was managed to maintain pre-dawn leaf water-potentials (PLWP) within the following ranges: (i) higher than –1.1 MPa (FI; fully irrigated); (ii) between –1.0 and –3.3 MPa (DI; deficit irrigated); or (iii) below –1.2 MPa, but not lower than –4.2 MPa (SI; severe deficit irrigated). The irrigation period lasted from 6 – 16 weeks after full bloom (AFB) in 2003, and from 5 – 19 weeks AFB in 2004. In 2003, full bloom was on 26 May; in 2004, it was on 3 June. Neither irrigation regime nor crop load affected flowering or flower quality the following Spring. The combined fruit yields [on a fresh weight (FW) basis] over both years in SI and DI trees were 49.0% and 81.6% of FI trees, respectively. The oil yields of SI and DI trees were 52.5% and 81.2% of FI trees, respectively. Fruit FWs in FI trees were greater than those of DI or SI trees at 8 weeks AFB. At harvest, FI trees bore the largest fruits, and SI trees the smallest fruits. The FWs of individual fruits at harvest in the FI and DI treatments decreased as crop load increased, but no such relationship was apparent for SI trees. The oil content of the mesocarp increased as PLWP increased from approx. –3.5 MPa to –1.5 MPa. The oil content of FI trees at harvest decreased from 53.1% to 45.7% dry weight as fresh fruit yield increased from 5 – 25 kg dm–2 trunk cross-sectional area. However, crop load did not have any effect on the oil content of the mesocarp in DI trees. Fruit maturation was delayed by irrigation. Maturation index also decreased (indicating delayed maturation) as the crop load on FI or DI trees increased, but did not vary with crop level in SI trees.

GA 3 increases fruit weight in ‘Yu Her Pau’ litchi

In order to increase the fruit weight of a shriveled-seed cultivar, trees of ‘Yu Her Pau’ litchi ( Litchi chinensis Sonn.) growing in Taiwan were sprayed with Gibberellic acid (GA 3) (ProGibb ®, 20% of GA 3) at 5 and 10 mg/l 14 days after full bloom (AFB) over 2 years. Both concentrations of GA 3 significantly increased fruit longitudinal and transversal diameter, and fruit, aril and pericarp weight (40–41 and 37–38 mm, and 27.3–28.4, 21.7–22.7 and 5.0–5.3 g, respectively) compared with control (35–36 and 33–34 mm, and 22.3–22.4, 17.8–17.9 and 3.9–4.0 g), but had no significant effects on seed weight, percentage of aril weight of total fruit weight or total soluble solids (0.5–0.7 g, 78.9–80.3% and 18.1–19.0 °Brix, respectively). Fruit characteristics within the two concentrations of GA 3 showed no significant difference. The results indicated that sprays of GA 3 should be evaluated in ‘Yu Her Pau’ commercial orchards, and in other elite cultivars.

The Effect of Water Deficit during Early Fruit Development on Olive Fruit Morphogenesis

Water deficit was applied between 4 and 9 weeks after full bloom by withholding irrigation from 3-year-old Olea europaea L. (`Leccino') plants grown in 2 L containers in a greenhouse. At 6, 8, and 22 weeks after full bloom (AFB), fruit were sampled for fresh weight and volume determinations, and then fixed for anatomical studies. Structural observations and measurements were performed on transverse sections at the point of widest fruit diameter using image analysis. Water deficit applied between 4 and 9 weeks AFB produced a significant decrease in predawn leaf water potential, which reached minimum values of -3.1 MPa. The applied water deficit reduced fruit fresh weight and volume at 8 and 22 weeks AFB. Fruit transverse area of the water deficit treatment was 50%, 33%, and 70% of the irrigated one at the 6-, 8-, and 22-week sampling dates, respectively. Mesocarp growth occurred for both irrigated and water deficit plants between 8 and 22 weeks AFB. At 22 weeks AFB differences between treatments were significant for mesocarp transverse area, but not for endocarp area. Mesocarp cell size, indicated by area, was significantly different between treatments at 8 and 22 weeks AFB. However, the mesocarp cell number was similar for both treatments at all times, and most mesocarp cells were produced by 6 weeks AFB. The growth of endocarp area showed the greatest shift in timing in response to the early water deficit. Ninety percent of endocarp growth had occurred by 8 weeks AFB in the irrigated treatment, but only 40% when the deficit irrigation treatment was imposed.

Growth and development of fruits of olive ‘Frantoio’ under irrigated and rainfed conditions

SummaryA field experiment was performed in Tuscany, Italy, whereby fruit growth and development of irrigated olive trees (Olea europaea L. ‘Frantoio’) were compared, at two stages of fruit development, with those of trees cultivated under rainfed conditions. The fresh weight of fruits from irrigated trees was significantly higher than that from rainfed trees at 21 weeks after full bloom (AFB), whereas there were no differences at 8 weeks AFB or in fruit dry weight at both dates. Mesocarp transverse equatorial areas were 15.6 and 13.5% greater for the irrigated treatment than rainfed cultivated trees at 8 and 21 weeks AFB, respectively. Endocarp transverse area did not increase between 8 and 21 weeks AFB, indicating that endocarp expansion had occurred completely by 8 weeks AFB. The endocarp transverse area of irrigated trees was greater than that of unirrigated trees. For both treatments, mesocarp transverse area increased about 2.5-fold from 8 to 21 weeks AFB. Growth of the mesocarp between sampling dates was mainly due to a more than two-fold increase in mesocarp cell size for both treatments, whereas cell number increased only slightly over the same period. Irrigation appeared to increase mesocarp cell size rather than mesocarp cell number on both sampling dates. There were no differences in mesocarp oil content between irrigated and rainfed trees either at 8 or at 21 weeks AFB.

Early growth and development of the olive fruit mesocarp

SUMMARYWe examined growth and development of the ‘Manzanilla’ olive fruit mesocarp in transverse equatorial sections during the first 12 weeks after full bloom (AFB). Sequential sampling and quantitative data provided an integrated view of the formation of this tissue. The mesocarp, or fruit flesh, was formed by relatively isodiametric parenchyma cells with a small number of isolated sclereids. By four weeks AFB a gradient in cell size characteristic of mature olive fruits began to appear. Biweekly measurements of cell size and number indicated that, as in other drupes, both cell division and expansion contribute to initial mesocarp growth. From six weeks AFB, further mesocarp growth was determined solely by cell expansion. Transverse areas of mesocarp and endocarp, also measured biweekly, revealed that both tissues expand in a similar manner until eight weeks AFB, after which mesocarp growth predominated.

The Relationship Between Leaf Area and Light Interception by Spur and Extension Shoot Leaves and Apple Orchard Productivity

The study evaluated the relationship of spur vs. extension shoot leaf area and light interception to apple (Malus {XtimesX}domesticaBorkh.) orchard productivity. Fifteen-year-old `Marshall McIntosh'/M.9 trees had significantly greater leaf area and percentage of light interception at 3-5 and 10-12 weeks after full bloom (AFB) than did 4-year-old `Jonagold'/Mark trees. Despite significant increases in leaf area and light interception with canopy development, linear relationships between total, spur, and extension shoot canopy leaf area index (LAI) and 1) light interception and 2) fruit yield were similar at both times. Mean total and spur canopy LAI and light interception were significantly and positively correlated with fruit yield; however, extension shoot LAI and light interception were poorly correlated with yield. In another study total, spur and extension shoot canopy light interception varied widely in five apple production systems: 15-year-old central leader `Redchief Delicious' MM.111, 15-year-old central leader `Redchief Delicious' MM.111/M.9, 16-year-old slender spindle `Marshall McIntosh' M.9, 14-year-old `Jerseymac' M.9 on 4-wire trellis, and 17-year-old slender spindle `MacSpur' M.9. Yields in these orchards were curvilinearly related to total and extension shoot canopy light interception and decreased when total light interception exceeded 60% and extension shoot interception exceeded 25%. Fruit yields were linearly and highly correlated (r2 = 0.78) with spur light interception. The findings support the hypothesis that fruit yields of healthy apple orchards are better correlated with LAI and light interception by spurs than by extension shoots. The results emphasize the importance of open, well-illuminated, spur-rich tree canopies for high productivity.

Changes of Respiration Rate, Ethylene Evolution, and Abscisic Acid Content in Developing Inflorescence and Young Fruit of Olive (Olea europaea L. cv. Konservolia).

Simultaneous measurements of respiration, ethylene production, and abscisic acid (ABA) concentrations, as well as the growth parameters length, fresh weight (FW), and dry weight (DW) of olive (Olea europaea L. cv. Konservolia) inflorescence were carried out at short intervals (3-7 days) during the period from bud burst until the 3rd week after full bloom (AFB), when young fruit reached 8 mm in length. The axis of inflorescence elongated remarkably during the 3rd week after bud burst (ABB), massive bract shedding occurred during the 4th week ABB, full bloom (FB) was observed 7 weeks ABB, and massive floral organ abscission 1 week AFB. The results showed a continuous increase in inflorescence FW and DW from bud burst until 4 days before FB. Respiration rate, ethylene production, and levels of ABA were relatively high during the first 3 weeks ABB. After this period, respiration and ethylene followed a similar pattern of changes, inversely to that of ABA concentration. An accumulation of inflorescence ABA 6 and 4 days before FB was associated with the minimum values of respiration and ethylene production on the same dates. The sharp decrease in the ABA concentration during FB and 3 days later was followed by a high rise in ethylene and an increase in respiration rate, which both rose further 1 week AFB. The results suggest a possible correlation of ABA with the early stage of floral abscission, whereas ethylene production seems to be correlated with the terminal separatory activity in olive inflorescence abscission processes.Key Words. Abscisic acid-Abscission-Ethylene-Inflorescence-Olive-Respirationhttp://link.springer-ny.com/link/service/journals/00344/bibs/18n1p1.html

Gas Exchange in Olive Fruit

Dry matter (DM) of olive fruit (cv. Leccino) constantly increased from fruit-set (mid-June) to the end of October. The oil content increased rapidly from the beginning of August, about 40-50 d after full bloom (AFB), to the end of October. As the oil content increased, the saccharide content decreased. On a DM basis, fruit dark respiration rate (RD) and stomatal conductance (Gs) were high soon after fruit-set, then strongly decreased. Gross photosynthetic rate (PG) in full sunlight was high in the first 3 weeks after fruit-set, when the chlorophyll (Chl) content and the ratio between fruit surface area and volume were high, then it progressively decreased. The fruit intercellular CO2 concentration (Ci) was always relatively high, particularly from September onwards. The PG increased following the increase of irradiance (I). The daily PG trend was similar to the I and temperature trends, showing the maximum values at 14:00 h. For a large part of the fruit growing period, during daylight, the CO2 intake by a fruit permitted the reassimilation of a large part (40-80%) of the CO2 produced by RD. The stomata in the first stages of fruit growth were oval and surrounded by guard cells, two months later they lost their shape and were covered by wax. The reduction in fruit PG during fruit growth could be connected to the reduction of the ratio between fruit surface area and fruit volume and the cellular differentiation, whereas the constant high Ci seems to exclude the influence of Gs decrease. Even if olive fruit is highly heterotrophic organ, its photosynthesis can considerably reduce the use of assimilates for respiration and favour fruit maintenance and growth.

Carbohydrate content of inflorescent buds of defruited and fruiting pistachio (Pistacia vera L) branches in relation to biennial bearing

SummaryChanges in carbohydrate content of inflorescent buds of fruiting and defruited branches of the same tree were measured in 1994 and 1995 in the period before and during bud abscission in pistachio (Pistacia vera L. cv. Aegenes) to investigate its relationship to inflorescent bud abscission. HPLC was used for soluble sugar analysis, while starch was hydrolyzed to glucose enzymatically and the amount of glucose was then determined using the glucose oxidaseperoxidase method. The effect of fruit on leaf net photosynthesis (Pn), chlorophyll a and b (Chl (a+b)) in leaves and specific leaf weight (SLW) was also investigated in 1995. Starch concentration was initially similar in buds of fruiting and defruited branches but became greater in buds of defruited branches from early June 1994 (57 d after full bloom (AFB)) and 20 June 1995 (61 dAFB), resulting in higher starch contents. Glucose and fructose concentrations were similar in flower buds throughout the whole period of measurement; inositol and sucrose (the most abundant sugar in flower buds) both became much lower in fruiting branches from early July 1994 (83 dAFB) and mid July 1995 (88 dAFB). The rapid decrease in sucrose concentration coincided with rapid seed growth and the greatest period of bud abscission in fruiting branches. During the same period, total sugar and total carbohydrate concentrations and contents were greater in buds of defruited branches. The presence of fruit increased Chl (a+b) content in leaves while decreasing SLW between 43 and 61 dAFB. During this same period, leaf Pn rates were greater in fruiting shoots than in defruited ones.

Thidiazuron affects fruit growth, ripening and quality of Actinidia deliciosa

SummaryThe effects of thidiazuron (TDZ) on growth, quality and ripening of kiwifruits were evaluated by comparison with untreated (control) and CPPU (cytokinin) treated fruits. Two weeks after full bloom (AFB), TDZ at 5, 10 or 20 ppm and CPPU at 20 ppm were applied to fruits by dipping them for about 5.s in aqueous solutions of the two compounds. TDZ remarkably increased fruit growth soon after application. The increase in size levelled off at 10 ppm and no further improvement in fruit size resulted from the 20 ppm treatment. At harvest, TDZ treated fruits, depending on the concentration, were 50% or 60% heavier than untreated ones. All TDZ concentrations used also gave a large (+44%) and similar increase in fruit dry weight. TDZ did not cause significant variations in the number and weight of seeds. TDZ caused some modification in fruit shape. It increased the percentage of fruits having a protruded distal end and tended to decrease the fruit length/average diameter ratio, especially at the higher concentrations. TDZ caused an increase in the size of all the tissues of the fruits without changing their relative proportions at harvest. TDZ treated fruits had an advanced and/or faster ripening (about one week) with respect to the control. This was clearly shown by the lower flesh firmness and total titratable acidity and the higher content of soluble solids and soluble sugars (although the total carbohydrate content was not affected) at harvest. After harvest, once full ripening was reached, all fruits had a soluble solids content of about 14.58 Brix and a flesh firmness of about 2.0 kgf, without differences due to treatments. In general, results of CPPU were similar to those of TDZ treated fruits at the same concentration (20 ppm). TDZ greatly stimulates fruit growth indicating that it can be a powerful tool for improving kiwifruit cropping.

Changes in Polyamine Levels in Relationship to the Double-sigmoidal Growth Curve of Peaches

Polyamines and the activities of their biosynthetic enzymes were evaluated during peach (Prunus persica L. `Biscoe') mesocarp (pulp) and seed growth starting at full bloom and until full fruit maturity at 14 weeks after full bloom (AFB). Mesocarp fresh mass exhibited a double-sigmoidal pattern characteristic of peaches. Seed fresh mass increased to a maximum of≈1 g at 4 weeks AFB then remained unchanged during the remaining weeks of sampling. Free putrescine, spermidine, and spermine levels were significantly higher in the flower bud, declined in the mesocarp tissue during the first 2 weeks AFB, then exhibited another increase between 2 and 6 weeks AFB. In contrast, conjugated spermidine and spermine levels were low in flower buds, then increased to their maximum level at 6 weeks AFB, then declined at full fruit development. Ornithine decarboxylase (ODC, EC 4.1.1.17) activity was high in flower buds (89.3 nmol·h-1·mg-1 protein) and in early stages of mesocarp development then declined to its lowest level (5.8 nmol·h-1·mg-1 protein) at full-fruit development. Arginine decarboxylase (ADC, 4.1.1.19) activity did not change during the first 6 weeks of mesocarp growth but declined later, reaching its lowest (1.95 nmol·h-1·mg-1 protein) at 14 weeks AFB. During the first 5 weeks AFB, ODC activity was 3.0- to 4.5-fold that of ADC activity; however, at full-fruit maturity (14 weeks AFB) the activities of both enzymes were similar. The slowdown in mesocarp growth during pit hardening between 6 and 9 weeks AFB did not change polyamines concentrations or their biosynthetic enzymes. Free spermidine and spermine levels declined during seed development; however, between 7 and 9 weeks AFB an increase in putrescine was observed. Similarly, conjugated putrescine increased substantially during seed growth reaching its highest level of 680 nmol·g-1 fresh mass at week 8 then declined at the later weeks, while conjugated spermidine and spermine peaked at week 10 to 1,169 and 2,148 nmol·g-1 fresh mass. ODC and ADC activities declined between 3 and 5 weeks AFB. However, a significant increase in ADC but not ODC activity in the seed tissue was observed during pit hardening between 6 and 10 weeks AFB. Based on the rapid increase in putrescine and ADC activity in the seed tissue, it appears that pit hardening may be a stress-related phenomenon. Data also suggest that polyamine levels in the mesocarp and seed tissue are independently regulated.

The Effect of BAS-125W on Apple Tree Growth, Fruit Quality, and Fireblight Suppression

In 1995, BAS-125W applied at 125 to 500 mg/liter 23 days after full bloom (AFB) to `Starkrimson Delicious'/MM 106 and MM111 reduced average shoot weight and length of the longest shoots in the top and scaffold limbs by 50% at the highest rate. The number of nodes on the lower 40 cm of each shoot was increased by 1.8 times by the growth retardant. The number of pruning cuts, pruning time, and pruning weight per tree was reduce by 30%, 20%, and 29%. Fruit diameter, color, soluble solids, starch, fruit weight, and fruit number per tree were not altered by BAS-125 W. Growth suppression appeared to be greater on trees with heavier crop loads. In 1996, BAS-125W applied at 250 mg/liter 8 days after full bloom was more effective than when applied 19 days AFB to `Starkrimson Delicious'/MM 106 and MM111. Multiple applications of two, three, and four sprays to the same trees at 3-week intervals further reduced shoot growth with each application. Four applications reduced shoot weight by 72%, shoot length by 60%, and basal shoot diameter by 25%, and the number of pruning cuts, pruning time, and pruning weight per tree was reduce by 75%, 55%, and 80%, respectively. Thinning activity of NAA, Sevin, or Accel was not affected by tank mixed sprays with BAS-125W when applied to Gala/M.27 trees 20 days AFB. Tank mixing BAS-125W with combinations of Vydate + Accel or Carbaryl + Accel + Oil did not alter fruit thinning of Fuji/M.27 (at 10 mm fruit diameter). In one experiment, BAS-125 may have potentiated thinning by ethephon and NAA 10 days AFB in another experiment. BAS-125 W sprays at petal fall + 1 and 2 weeks later significantly suppressed % infection by fireblight, Erwinia amylovora, in inoculated shoots. In addition, BAS-125W reduced canker length in the first-year growth in shoots inoculated 2 weeks after treatment.

Peach and Nectarine Fruit Softening Following Aminoethoxyvinylglycine Sprays and Dips

AVG sprays applied to `Redhaven' peach (Prunus persica L. Batsch) trees 53, 72, 80, 87, or 94 days after full bloom (AFB) slightly delayed the first harvest date. Applications at 53 or 94 days AFB slightly delayed cumulative second and third harvests. The fourth (final) harvest was not delayed by any AVG spray. Firm commercial-harvest peach and nectarine fruit submerged for 60 s in AVG solutions softened more slowly than the controls when kept at room temperature (≈24 °C) for 3 to 12 days. AVG-treated fruit dipped in ethephon after 4 days showed an increased rate of softening compared to fruits treated only with AVG. Fruit submerged in AVG solutions and stored at 1.5 or 4.5 °C for 12 to 18 days did not differ in firmness from the controls upon removal from cold storage but sometimes softened more slowly after storage. Ethylene evolution from AVG-dipped fruit was not measureable even after it was kept at room temperature for 12 days. Chemicals used: Aminoethoxyvinylglycine hydrochloride (AVG); 2-chloroethylphosphonic acid (ethephon).

Influence of CPPU on carbohydrate accumulation and metabolism in fruits of Actinidia deliciosa (A. Chev.)

A trial was carried out to evaluate the influence of N-(2-chloro-4-pyridyl)-N′-phenylurea (CPPU), a diphenylurea derivative cytokinin, on kiwi productivity, on carbohydrate accumulation and metabolism and on post-harvest fruit performance. CPPU (20 ppm) was sprayed on fruitlets inside the canopy 2 weeks after full bloom (AFB). CPPU influenced fruit growth soon after treatment and, at harvest, treated fruit weight and, consequently, yield per vine were about 25% higher than the control. During fruit growth, soluble sugars (glucose, fructose and sucrose) were higher in treated fruits than in the control ones. In the first period of fruit development glucose was the most abundant carbohydrate and CPPU treatment increased the fruit glucose content significantly. During the period of starch accumulation, treated fruits showed a higher starch content and a higher ADP-glucose pyrophosphorylase activity. Starch accumulation started earlier in treated fruits than in the control ones. At the end of the growing season the degradation of starch in treated fruits started earlier and/or was faster than in the control ones, so that at harvest treated and control fruits contained the same amount of starch. As a consequence, treated fruits at harvest had higher contents of soluble sugars. This indicates that CPPU induced faster and/or advanced fruit ripening. The chlorophyll content was higher in CPPU treated fruits. During storage, the differences in carbohydrate content disappeared and treated fruits performed as well as control ones, maintaining good quality for up to 6 months.