Pre-harvest foliar application of calcium and boron influences physiological disorders,fruit yield and quality of strawberry (Fragaria × ananassa Duch.)

Studies were conducted in ‘Chandler’ strawberry to determine if pre-harvest foliar application of Ca, B or their combination influences physiological disorders, fruit yield and quality or not. For this, treatments consisted of (i) five sprays of calcium as CaCl₂ (first spray was performed at the petal fall stage and later at 7 days interval), (ii) three sprays of boron as boric acid (first spray at the beginning of flowering and later at 15 day interval), (iii) combination of (i) and (ii), and (iv) plants sprayed with water served as the control. Results indicated that fruit harvested from plants, which were sprayed either with Ca or Ca + B had significantly lesser incidence of albinism (6.7 and 6.5%), and grey mould (1.3 and 1.2%) than those harvested from plants sprayed either with B alone or in control. Although, B alone could not influence the incidence of albinism and grey mould, but it reduced fruit malformation (3.4 and 3.1%) significantly. Further, Ca, B or their combination had not influenced the individual berry weight, but marketable fruit yield differed significantly. The lowest marketable fruit yield (149.3 g/plant) was recorded in plants under control, and the highest (179.2 g/plant) in plants sprayed with Ca + B. Similarly, such fruit were firmer; had lower TSS, higher acidity and ascorbic acid content at harvest than those in control. Similarly, such fruit after 5 days storage were firmer and brighter, and have significantly lower TSS (7.9 and 7.8%); higher ascorbic acid content (43.7 and 45.0 mg/100 g pulp) and acidity (1.08 and 1.07%) than those in control or those receiving B alone. Incidence of grey mould was significantly lesser in fruit, which received Ca (2.2%) or Ca + B (1.9%) than those, which received either B (8.1%) alone or those in control (8.4%). Our studies indicated that pre-harvest foliar application of Ca + B is quite useful for reducing the incidence of disorders and getting higher marketable yield in ‘Chandler’ strawberry.     

Sequential foliar application of vermicompost leachates improves marketable fruit yield and quality of strawberry (Fragaria × ananassa Duch.)

The objective of the study was to determine the effect of foliar application of vermicompost leachates on growth, yield and quality of strawberry (Cv. Chandler). For this, three leachates collected from vermicomposting of cow dung (FCD), vegetable waste (FVW) and mixture of cow dung and vegetable waste in 1:2 ratio (FCVW) were used at 2 ml l⁻¹ at monthly interval (total five sprays) in strawberry. The results indicated that foliar application of vermicompost leachates improved leaf area (10.1–18.9%), dry matter of plant (13.9–27.2%) and fruit yield (9.8–13.9%) significantly over control (water spray only). Foliar application of FCVW reduced albinism (from 12.1 to 5.7%), fruit malformation (11.2–8.5%) and grey mould (5.1–2.6%) thus improving marketable fruit yield (26.5% higher) with firmer fruits of better quality. The foliar application of FCD and FVW also improved these parameters and resulted in to higher marketable fruit yield (12.6 and 17.8% higher, respectively) compared to control. The study confirmed that leachates derived from composting processes have potential use as foliar fertilization for strawberry.     

Fruit calcium content and lipoxygenase activity in relation to albinism disorder in strawberry

Nutrient elements and lipoxygenase (LOX) activity were determined in strawberry fruit to establish a relationship, if it exists, between nutrient ratios (N/Ca and K/Ca), and lipoxygenase activity with albinism disorder. About 33% strawberry fruit were affected by albinism. Etna had highest incidence of albinism (48.6%) and Sweet Charlie the lowest (16.2%). Dry matter content (%) was lower in albino fruit (5.23%) than normal fruit (7.36%). The concentration of N, P, and Mg did not differ significantly, but that of K (1.87 mg g⁻¹ fresh weight) was notably higher and of Ca (0.105 mg g⁻¹ fresh weight) was lower in albino fruit than normal fruit. Consequently, the nutrient ratios, N/Ca (9.78) and K/Ca (16.96) were higher in albino fruit than normal fruit. Cultivars differed widely in respect to dry matter (%), mineral content and nutrient ratios. LOX activity determined on dry weight or fresh weight basis was significantly higher in albino fruit than normal fruit, with significant differences among cultivars. Positive correlations existed between nutrient ratios and albinism incidence (r = +0.338), LOX activity and albinism incidence (r = +0.412), and LOX and nutrient ratios (r = +0.448). Thus, it appears from the study that calcium and LOX activity may not the basic cause of albinism in strawberry, but these may be involved in senescence or fruit ripening process, as LOX activity was lower in albino than in normal fruit.     

Gibberellic acid influences the production of malformed and button berries,and fruit yield and quality in strawberry (Fragaria × ananassa Duch.)

Experiments were conducted to observe the effects of foliar application of gibberellic acid on vegetative growth, flowering, fruiting and various disorders in ‘Chandler’ strawberry. GA₃ (75 ppm) was applied to the strawberry plants either during mid-November (at fruit bud differentiation stage), or mid-February (pre-flowering stage) or at both times. Fruit under control were sprayed with tap water only. Observations were recorded on vegetative attributes like crown height, crown spread, petiole length, leaf number, leaf area; flowering and fruit set, fruit size; production of albino, malformed and button berries, total yield and marketable fruit yield and quality parameters, like juice content, TSS, ascorbic acid contents, acidity etc. Results indicated that GA₃ (75 ppm) spray either during mid-November or mid-February or at both times has favourably influenced all vegetative attributes of ‘Chandler’ strawberry over control. Similarly, fruit set was increased, and production of malformed and button berries was reduced, but albinism remained unaffected. Although individual berry weight was reduced slightly, but fruit number, total as well as marketable yield was increased tremendously over control with no adverse effect on fruit quality parameters. In all, spraying GA₃ both during mid-November and mid-February was much more effective in achieving the desirable results than single application of GA₃ either during mid-November or mid-February.     

Relationship between light,fruit and leaf mineral content with albinism incidence in strawberry (Fragaria x ananassa Duch.)

A study was conducted in strawberry to establish a relationship between shading, mineral nutrient of leaves and fruits with albinism incidence. Plants grown under shade produced albino fruits in higher proportion than those grown in open fields. Similarly, plants under shade produced smaller sized fruits and have lower fruit yield. Among cultivars, Etna had highest incidence of albinism (49.6%) and Sweet Charlie the lowest (14.4%). Dry matter content (%), concentration of five major nutrients, viz. N, P, K, Ca, Mg, S and N:Ca and K:Ca nutrient ratios did not differ significantly in the leaves of plants producing normal or albino fruits. However, in contrast, the concentration of K was notably higher (1.97 mg g⁻¹ fresh tissue weight) and that of Ca was lower (0.098 mg g⁻¹ fresh tissue weight) in albino fruits than normal ones. Consequently, the ratios of N:Ca (11.34) and K:Ca (20.08) were higher in albino fruits than normal ones. Cultivars also differed widely in respect to dry matter (%), mineral content and nutrient ratios. Thus, it appears that lower light intensity favours the development of albinism in strawberry, and it seems that calcium is not the basic cause of albinism, but increased vigour associated with overuse of N and K might be positively associated with it.     

Effects of defoliation on fruit growth,carbohydrate reserves and subsequent flowering of ‘Hayward’ kiwifruit vines

A partial defoliation study was carried out on ‘Hayward’ kiwifruit vines with the aim of evaluating effects on fruit yield, changes in concentration of carbohydrates, and return bloom. At full bloom, ‘Hayward’ kiwifruit vines trained to the pergola system were submitted to 0% (control), 50% and 75% defoliation in the 2.0 m wide central horizontal area of the canopy. This area represents the vine ‘replacement cane zone’ (RCZ), whereas the remaining external area represents the ‘fruiting zone’ (FZ). Removing 50% of the leaves resulted in a small (−9 g in the RCZ and −3.3 g in the FZ), but significant, reduction in fruit weight compared to the control vines. More severe defoliation (75%) reduced fruit weight by 13 g in the RCZ and 7 g in the FZ. The defoliation treatment reduced the concentrations of starch and total soluble carbohydrates (glucose + fructose + sucrose) in the shoots and starch in trunk bark compared to those in control vines. The treatments caused a large reduction in return bloom, expressed as number of flowers per winter bud, by about 25% and 53% in vines with 50% and 75% defoliation, respectively.     

Effects of bagging on fruit development and quality in cross-winter off-season longan

Clusters of cross-winter off-season longan (Dimocarpus longan Lour) cv. Chuliang were bagged with three types of bags: perforated translucent plastic bag (TPB), white adhesive-bonded fabric bag (WAFB) with about 70% light transmittance, and black adhesive-bonded fabric bag (BAFB) with <10% light transmittance. Bagging treatments began at 34 days after anthesis and continued until harvest. The results showed that bagging modified the microenvironment for fruit development. Bagging with TPB was most effective in increasing humidity, and air moisture within TPB maintained above 90% from 2 weeks after bagging. Bagging with BAFB or WAFB increased humidity most of the time, and the effect was more prominent when the weather was very dry (RH < 60%). All bag types tended to increase temperature and promoted fruit development, resulting in larger sized fruit. Bagging tended to promote early fruit drop but reduced late fruit drop, and the final fruit retention rate was not significantly affected by bagging. Bagging with different materials showed differential effects on incidence of fruit cracking. WAFB and BAFB reduced cracking incidence significantly as compared to the control (5.1% and 11.6% vs 32.8%). Sugar content was not significantly affected by bagging but organic acids including vitamin C (Vc) were considerably affected. Concentration of malic acid, the dominant organic acid in longan aril, was 605.6, 830.0, 1161.0 and 1428 μg/g FW in TPB, BAFB, WAFB and the control. Vc in the aril was significantly reduced by BAFB (108.4 μg/g FW), slightly increased by WAFB (183.9 μg/g FW) and significantly increased by TPB (264.5 μg/g FW) as compared with the control (174.7 μg/g FW). Pericarp of fruit bagged with TPB had a slightly higher content of Vc (1337 μg/g FW), while those bagged with BAFB (873.6 μg/g FW) and WAFB (787.4 μg/g FW) had significantly lower Vc contents than the control (1243 μg/g FW). The responses of oxalate and Vc contents in the aril and the pericarp to bagging treatments showed an opposite trend. The results suggested that WAFB increased fruit size and fruit retention rate while significantly reduced fruit cracking incidence and could be a promising practice for cross-winter longan production.     

Bio-efficiency of compost extracts on the wet rot incidence,morphological and physiological growth of okra (Abelmoschus esculentus [(L.) Moench])

An experiment was carried out to investigate the efficacy of rice straw and empty fruit bunch (EFB) of oil palm compost extracts either fortified or unfortified with Trichoderma harzianum on morpho-physiological growth and occurrence of Choanephora wet rot of okra. Treatments tested were water (control) (T1), rice straw (RST) compost extract (T2), Trichoderma-enriched RST compost extract (T3), empty fruit bunch of oil palm compost extract (T4), Trichoderma-enriched EFB compost extract (T5), aqueous suspension of Trichoderma (T6), and a fungicide Dithane M-45^® (2 g l⁻¹ of water) (T7). The experimental results revealed significant variations amongst the treatments in respect of morphological characters, e.g. shoot length, tap root length, number of leaves per plant, and leaf area. The shoot and tap root length, number of leaves per plant, leaf area were significantly (P ≤ 0.05) higher in Trichoderma-enriched RST compost extracts (T3) followed by Dithane M-45^® (T7), Trichoderma-enriched EFB extracts (T5), RST (T2), EFB (T4) and aqueous suspension of T. harzianum (T6) in both Choanephora inoculated and uninoculated (control) plots. Similarly, net photosynthetic rate and chlorophyll content were higher in plants receiving Trichoderma-enriched RST compost extracts (T3) with 76.2% reduction in Choanephora wet rot incidence when compared with rest of the treatments. These experimental results revealed that morpho-physiological characters of okra could be modified by the application of Trichoderma-enriched compost extracts. This suggests that use of Trichoderma-enriched compost extracts would be more beneficial in environmentally friendly okra cultivation and may be used as an alternative to inorganic fertilizers/fungicides to enhance plant growth and reduce disease incidence subsequently, resulting in higher yield.     

Effects of greenhouse cooling method on growth,fruit yield and quality of tomato (Solanum lycopersicum L.) in a tropical climate

A tomato (Solanum lycopersicum L.) crop was grown in four greenhouses during the dry season 2005/06 in Central Thailand. Sidewalls and roof vents of two greenhouses were covered with nets and these greenhouses were mechanically ventilated when air temperature exceeded 30 °C (NET). The other two greenhouses were covered with polyethylene film and equipped with a fan and pad cooling system (EVAP). Overall mean air temperature was significantly reduced by 2.6 and 3.2 °C (day) and 1.2 and 2.3 °C (night) in EVAP as compared to NET and outside air, respectively. Temperature maxima in EVAP averaged about 4 °C lower than in NET and outside. The relative humidity was around 20 and 30% (day) and 10 and 15% (night) higher in EVAP than in NET or outside, respectively. Vapour pressure deficit averaged 0.25 kPa in EVAP, 1.03 kPa in NET and 1.48 kPa outside. The crop water-consumption was significantly lower in EVAP (1.2) than in NET (1.8 L plant⁻¹ day⁻¹), which is ascribed to reduced transpiration in EVAP. Total fruit yield was similar in NET (6.4 kg plant⁻¹) and EVAP (6.3 kg plant⁻¹). The quantity of undersized (mostly parthenocarpic) and blossom-end rot (BER)-affected fruits was reduced in EVAP. However, the proportion of marketable yield was significantly higher in NET (4.5 kg plant⁻¹) than in EVAP (3.8 kg plant⁻¹), owing largely to an increased incidence of fruit cracking (FC) in EVAP. Higher FC but lower BER incidence coincided with higher fresh weight and Ca concentration in the fruits in EVAP. It is concluded that in regions with high atmospheric relative humidity evaporative cooling without technical modifications allowing dehumidification will not improve protected tomato production.     

Response of evergreen perennial tree crops to gibberellic acid is crop load-dependent: II. GA3 increases yield and fruit size of ‘Hass’ avocado only in the on-crop year of an alternate bearing orchard

Despite problems of low fruit set, small fruit size and alternate bearing, the Hass cultivar dominates commercial avocado production worldwide. To increase yield and fruit size, gibberellic acid (GA₃) (25 mg L⁻¹) was applied at different stages of ‘Hass’ avocado tree phenology: (i) mid–late April (flower abscission), end of June–beginning of July (fruit abscission and beginning of the exponential phase of fruit growth), and mid-January (beginning of pre-harvest fruit drop); (ii) end of June–beginning of July; and (iii) mid-September (near the end of the major fruit abscission period; period of exponential fruit growth). In both years of the research, applications of GA₃ in April and June–July were within the periods of intense flower and fruit abscission, respectively; fruit abscission was low in September and January. Maximum air temperature was not related to flower or fruit abscission. In the on-crop year (391 fruit per untreated control tree), a single application of GA₃ at the end of June–beginning of July significantly increased total yield (kilograms only) and yield of commercially valuable fruit (178–325 g/fruit) (as kilograms and number per tree) compared with the control (P < 0.0001). GA₃ applied in September increased total yield (kilograms only) and yield of commercially valuable fruit (kilograms and number per tree) to values intermediate to and not significantly different from all other treatments, except trees receiving multiple applications of GA₃. This treatment reduced total yield and yield of commercially valuable fruit (kilograms and number per tree) relative to all treatments (P ≤ 0.0002). In contrast, during the off-crop year (32 fruit per control tree), no GA₃ treatment had a significant effect on yield or fruit size compared with the control and all other GA₃ treatments. For ‘Hass’ avocado, there was no negative effect from applying GA₃ at the end of June–beginning of July in both the off- and on-crop years; 2-year cumulative total yield and yield of commercially valuable fruit were increased by 27 kg (128 fruit) and 22 kg (101 fruit) per tree, respectively, above the yield of untreated control trees (P < 0.0001).     

Root aeration improves yield and water use efficiency of tomato in heavy clay and saline soils

Water logging and salinity of the soil alter both the physical and biological environment of plant roots. In two experiments, we investigated the effects of imposed aeration on yield and the physiological response of tomato (Lycopersicon esculentum L.) variety Improved Apollo growing under protected conditions over a range of salinities (the salinity experiment), and under constant field capacity (FC) or drier soil conditions (the moisture experiment). Subsurface irrigation with aerated water (12% air in water) stimulated above-ground growth, and enhanced the reproductive performance through earliness for flowering and fruiting compared with the control. Fruit yield of tomato with aeration in the moisture experiment was increased by 21% compared with the control (4.2 kg versus 3.7 kg per plant), and the effect of aeration on fruit yield was greater in FC than in the drier treatment. Fruit yield was increased by 38% in saline soil due to aeration compared with the non-aerated control. Increasing salinity from 2 to 8.8 dS m⁻¹, and 10 dS m⁻¹ reduced fruit yield by 18% and 62%, respectively, but 4 dS m⁻¹ did not suppress yield. Aeration in both the experiments increased plant water use and water use efficiency (WUE), expressed as weight per unit of applied water. Biomass WUE was greater by 16% and 32% in the moisture and salinity experiments, respectively. The increased yield with aeration was also accompanied by an increased harvest index (HI) defined as the proportion of dry fruit biomass to total dry biomass, greater mean fruit weight, high fruit DM, and increase in leaf chlorophyll content and shoot: root ratio, and a reduced water stress index (computed from the difference between air and leaf temperature). The benefit gained from aerating irrigation water was not only observed under conditions where air-filled porosity may be low (e.g., in poorly structure sodic soils, or at field capacity in clay soils), but also in drier soils.     

Responses of fruit growth,quality, and productivity to crop load in apple cv. Ultra Red Gala/MM111

The effects of three crop load densities (4, 6 and 8 fruit per cm² of the cross-section of each tree branch, BCSA) on fruit growth, yield, fruit quality and vegetative growth were studied in apples (Malus × domestica Borkh) Ultrared Gala/MM111, from the fourth leaf (2006–2007 season) to the sixth (2008–2009 season). The maximum fruit growth rate was reached between 90 and 108 days after full bloom (DAFB), with values above 2.6 g day⁻¹. Accumulated yields to the sixth leaf reached 181, 157 and 123 Mg ha⁻¹ in the high, medium and low crop loads, respectively. Mean fruit weight decreased with increasing fruit crop load but the yields of fruit weight over 194 g were similar in all crop loads; the highest crop load exceeded the lowest crop load by 18.8 and 27.5 Mg ha⁻¹ of fruit weight of more than 172 and 154 g, respectively. The yields of harvested fruit exceeding 75% with red coloring did not show major differences, while fruit classified as 50–75% with red coloring were less common in the low crop load. No major differences were found at the end of the study in vegetative growth in the different seasons, nor in plant size. The reduction in mean fruit weight and in the percentage of fruit with good coloring was compensated by the increase in yields, thus not resulting in an effective reduction in the quality of the harvested fruit. The level of plant development reached with a semi-vigorous rootstock and high fruit loads allowed obtaining high fruit yield earlier and of good quality.     

Some physico-chemical characteristics of black mulberry (Morus nigra L.) genotypes from Northeast Anatolia region of Turkey

In this study, some selected physico-chemical properties (antioxidant activity, ascorbic acid, fatty acids, fruit colour, fruit juice yield, fruit weight, organic acids, pH, total phenolic and total soluble solid contents) of five black mulberry (Morus nigra L.) genotypes grown in the Northeast Anatolia region of Turkey was investigated. The total phenolic and antioxidant activity of methanol extract of black mulberry fruits were determined according to Folin-Ciocalteu and β-carotene bleaching method assays, respectively. Fatty acids of mulberry fruits were determined by using gas chromatography. Total phenolic content was observed in black mulberry fruits between 1943 and 2237 mg gallic acid equivalents/100 g fresh mass. The vitamin C content of genotypes varied between 14.9 and 18.7 mg/100 ml. The major fatty acids in all mulberry fruits were linoleic acid (53.57–64.41%) and palmitic acid (11.36–16.41%). Antioxidant activity of black mulberry genotypes was found between 63% and 76%, which lower than standard BHA and BHT. Regarding organic acid content, malic acid was the most predominant with a range of 123–218 mg/g followed by citric acid (21–41 mg/g). The results of the study are helpful for attempting crop improvement in black mulberry for bringing to cultivation.     

Fruit growth and chemical properties of Ribes magellanicum “parrilla”

The aim of this work was to study the time course and pattern of fruit growth and the evolution of some of the chemical attributes such as soluble solids, acidity, and anthocyanin content in Ribes magellanicum plants growing in a natural environment near Ushuaia city, Tierra del Fuego (Argentina). Fruit growth and composition presented significant changes along the days from the full bloom phase. Fresh and dry fruit weight exhibited a typical double sigmoid curve. The first period of rapid fresh fruit growth was from full bloom phase until 28 days after, followed by a lag period until 42 days from the full bloom phase, and then by a second period of rapid increase until 56 days from the full bloom phase. Then, fresh fruit weight increased slowly (days 70–98 from the full bloom phase), reaching its maximum. Afterwards, fresh fruit weight decreased significantly until the end of the summer, and the fruiting period approximately ended 112 days from full bloom phase. On a dry weight basis the maximum fruit biomass was reached 98 days from the full bloom phase. Evolution of fruit growth was related with the compositional changes evaluated. By day 98 from the full bloom phase, soluble solids (17.5°Brix) and anthocyanin content (240.1 mg/100 g fruit fresh weight) were at their maximum, while at this time the total titratable acidity was at a minimum (0.4%). The results obtained not only contribute to the knowledge of the quantitative content of anthocyanin, a metabolite with nutraceutical value, but also give some tools for the definition of the optimal harvest time of R. magellanicum fruits, which it is important for fruit destination.     

Influence of growth conditions on yield,quality and diseases of strawberry (Fragaria x ananassa Duch.) var Ofra and Chandler under mid hills of Sikkim Himalaya

Field experiments were conducted during 2005–09 at ICAR Sikkim Centre, Tadong, East Sikkim, India at an altitude of 1400 m amsl to identify the suitable environment for high production of good quality fruits with less diseases for strawberry varieties Ofra and Chandler. Both the varieties were grown under low cost polyhouse, plastic tunnel and open conditions. Maximum number of flower trusses per plant was recorded in Chandler under open condition (13.0) followed by plastic tunnel (12.7). The maximum number of fruits per inflorescence was found in Ofra (7.12) under polyhouse while maximum number of runners per plant was observed in Ofra (12.3) in open conditions. Plastic tunnel with Ofra produced highest fruit weight (26.2 g), fruit length (5.5 cm) and fruit diameter (3.9 cm). Best fruit quality in terms of TSS (6.8%), lower acidity (0.83%) and total sugar (6.3%) was observed in Chandler under plastic tunnel conditions. The highest total fruit yield was recorded with Ofra under plastic tunnel (40.2 t/ha) but the maximum marketable yield was obtained in Chandler under plastic tunnel (35.3 t/ha). Diseases were found to be less prevalent in tunnel as compared to polyhouse and open conditions.     

Optimising quality-parameters of apple cv. ‘Pigeon’ by adjustment of nitrogen

To improve the productivity and quality of the apple cultivar ‘Pigeon’ the influence of 5 fertigation levels (14, 42, 70, 112, 224 mg N/l) and 3 widths of herbicide strip (0.2, 0.5, 1.0 m) were investigated on growth, yield and post-harvest quality/colour development of fruit. ‘Pigeon’ apples are picked when ca. 20% of the fruit skin has turned red, the fruit are then exposed to a sunning period on the orchard floor of 2–3 weeks to enhance red colour development (80% red skin); however the internal quality deteriorates during this period. Fruit drop occurs if fruit are left on the tree to develop colour. This study focused on how to reduce the length of the post-harvest sunning period to maximise both colour development and fruit quality. It was demonstrated that 14 mg N/l resulted in a low yield, small fruit, low vegetative growth, and low N content in leaf dry matter, but good fruit colour development. Excessive N fertigation (224 mg N/l) did not produce the significantly highest yield or the largest fruit, but it did enhance vegetative growth and resulted in less fruit colouration. N fertigation influenced optimal picking date; higher N fertigation delayed the time of picking, and increased the incidence of green fruit. Fruit from the high-N treatments required more days of post-harvest sunning to obtain the comparable red skin colour than fruit from the lower N-treatments. However, when all treatments were picked at ca. 20% fruit coloration it was not possible to reduce the length of post-harvest sunning period by N-supply. Most of the post-harvest colour development occurred within the first 6–9 days following harvest; colour developed on both sides but was enhanced on the shade side of the fruit. The shade side of the fruit had a greater potential for better red colour development than the blush side of the fruit.     

Berberis buxifolia fruiting: Kinetic growth behavior and evolution of chemical properties during the fruiting period and different growing seasons

This work studied the growth of Berberis buxifolia fruits and some of their chemical attributes during the fruiting period and different growing seasons (2004/2005, 2005/2006, 2006/2007) from November (14 days from full flower phase) till March (126 days from full flower phase) for plants growing in a natural environment near Ushuaia city (Tierra del Fuego, Argentina). B. buxifolia fruit growth and composition presented significant changes during the fruiting period and the studied growing seasons. Fresh and dry weight of B. buxifolia fruits exhibited a typical double sigmoid curve. The first period of rapid growth was from full flower phase till 42–56 days after, while the second phase of rapid growth began around the 56–70 days from full flower and ended approximately 4 months later. On a dry weight basis the maximum fruit biomass (119.5 mg) was reached 112 days after full flower while maximum fresh weight fruit biomass (424.3 mg) occurred by day 84. Evolution of fruit growth was related with the compositional changes evaluated. By day 126 from full flower, soluble solids (24.9°Brix) and anthocyanin concentration (761.3 mg/100 g fruit fresh weight) were at their maximum values, while at this time the total titratable acidity was at a minimum value (2.56%). The results obtained not only contributes to the knowledge of the quantitative content of anthocyanin, a metabolite with nutraceutical value but, gives some tools for the definition of the optimal harvest time of B. buxifolia fruits, what it is important for fruit destination.     

Effects of plastic mulches on root zone temperature and on the manifestation of tomato spotted wilt symptoms and yield of tomato

Tomato spotted wilt (TSW) disease is a serious constraint to tomato production in various regions of the world. The effect of TSW on tomato yield is largely influenced by time of infection. Early infection usually results in severe stunting of the seedling and even death of the plant. Plastic film mulches affect both the incidence of TSW, and plant growth and yield of tomato. The objective of the present study was to determine the effect of root zone temperature (RZT) as affected by plastic film mulch on the manifestation of symptoms of TSW, and growth and yield of tomato plants either artificially inoculated with tomato spotted wilt virus (TSWV) or under natural TSW infection. In artificially inoculated plants as well as in plants under natural TSW infection, vegetative top fresh weight (FW) and fruit FW both increased with the length of time after transplanting that the plants remained free from TSW symptoms. The root zone temperature was highest under black mulch (seasonal mean = 27.5 °C), followed by gray (27.0 °C), silver (25.8 °C), and white (24.8 °C) mulches. The plants grown on black mulch showed the earliest appearance of TSW symptoms, and had significantly reduced vegetative growth and fruit yields compared to plants on the other mulches. In conclusion, utilization of plastic mulches that created conditions of high RZT stress resulted in reduced plant growth and yield and predisposed the plants to earlier expression of TSW symptoms compared to plants grown at RZTs more favorable to tomato plant growth (optimal RZT = 26.1 °C [Díaz-Pérez, J.C., Batal, K.D., Granberry, D., Bertrand, D., Giddings, D., Pappu, H., 2003. Vegetative top growth and yield of tomato grown on plastic film mulches as affected by the appearance of symptoms of Tomato spotted wilt virus. HortScience 38, 395–399]). Since these plant responses to TSW under heat stress occurred in artificially inoculated plants as well as in plants under natural TSW infection, high RZTs probably affected the plants directly, independently of any possible effects on the thrips vectors.     

Reduction of apple tree height (Malus domestica Borkh) cv. Ultra Red Gala/MM111 does not decrease fruit yield and quality

In Chile, like in other countries, a high percentage of apple (Malus domestica Borkh) orchards are grafted on vigorous or semi-vigorous rootstocks. The need to decrease the amount of labor involved and increase efficiency has motivated this study on the effect of reducing the height of cv. Ultra Red Gala/MM111 trees in a commercial orchard in the Maule Region of Chile. Apple trees were planted in 2003, and their tree heights were adjusted to 2.5, 3.0 and 3.6 m prior to blooming in 2006. The reduction of plant height from 3.6 m to 2.5 m determined a significant reduction in canopy volume (26% and 29% in 2007/2008 and 2008/2009, respectively), but no differences were detected in leaf area index (LAI) and the photosynthetic active radiation (PAR) transmitted through the canopy. However, a higher proportion of the canopies of the shorter trees had over 30% of incident PAR, the threshold for the production of good fruit quality and flower-bud differentiation. There were no differences in fruit production among plant heights, accumulating 131 tonnes ha⁻¹ in the three growing seasons. Over the three seasons, the shortest plants (2.5 m) required 19, 57 and 42% less labor time at harvest, respectively, than the plants maintained at a height of 3.6 m. There were no evident differences in fruit quality among the treatments; flesh firmness varied between 73.0 and 74.0 N, soluble solids between 11.6 and 12.6°Brix, mean weight between 180 and 200 g, and the percentage of red coloring exceeded 59% of the Premium fruit in the three growing seasons. Our results suggest that it is possible to manage plants with reduced height on semi-vigorous rootstocks and thus reduce the time necessary for harvesting, without affecting fruit yield and quality.     

Response of evergreen perennial tree crops to gibberellic acid is crop load-dependent. I: GA3 increases the yield of commercially valuable ‘Nules’ Clementine Mandarin fruit only in the off-crop year of an alternate bearing orchard

Worldwide, gibberellic acid (GA₃) is used routinely to increase fruit number and size of seedless mandarins. The efficacy of seven combinations of GA₃ concentrations and application times to maximize total yield and yield of commercially valuable fruit (diameter 57.2–76.2 mm) of ‘Nules’ Clementine mandarin (Citrus reticulata Blanco) was determined in a commercial orchard. GA₃ applied during the period of intense flower abscission failed to reduce the total number of abscised flowers in both the light off- and heavy on-bloom years. No GA₃ treatment reduced fruit abscission when trees were setting the low yield off-crop. However, all trees receiving GA₃ in the high yield on-crop year had fewer abscised fruit than untreated control trees (P = 0.0188) and GA₃ applied 10 days after 75% petal fall and in July increased the number of fruit retained on tagged branches >20% compared to control trees (P = 0.0005). Maximum air temperature was not related to flower or fruit abscission. In the off-crop year (548 fruit per untreated control tree), it was necessary to apply 15 or 25 mg L⁻¹ GA₃ at 60% bloom, 90% bloom, 75% petal fall and 10 days after 75% petal fall to significantly increase the number of fruit per tree and yield of commercially valuable fruit (kilograms and number per tree) (P < 0.0001) above that of control trees, with no reduction in total kilograms per tree. In the following on-crop year, it was better not to apply GA₃: no treatment increased total yield or fruit size and five of seven GA₃ treatments tested reduced total yield as kilograms and number of fruit per tree (P = 0.0003). The results provide strong evidence that GA₃ efficacy is crop load-dependent and dictate that crop load should be considered when using GA₃ to increase fruit set or fruit size of mandarins.