Mature Kiwifruit Research Articles

Effect of nanocomposite-based packaging on postharvest quality of ethylene-treated kiwifruit ( Actinidia deliciosa) during cold storage

A novel nanocomposite-based packaging (NCP) was prepared by blending polyethylene (PE) with nano-Ag, nano-TiO 2 and montmorillonite. The effects of NCP on the quality parameters of ethylene-treated mature kiwifruit were investigated during the 42 d of storage at 4 °C. The results showed that adding nanoparticles to the PE significantly decreased the oxygen, water vapor permeability and longitudinal strength, and inhibited spore germination. The weight loss, softening, color variation and soluble solid content of kiwifruit were significantly inhibited by 22.67%, 124.84%, 23.46% and 14.42% respectively, which indicated that NCP could delay the ripening of kiwifruit. However, ascorbic acid and total phenols contents in NCP-treated fruit were increased compared with the controls. Additionally, kiwifruit in NCP exhibited 57.44% lower headspace ethylene concentration, 29.44% for malondialdehyde (MDA), lower polyphenol oxidase (PPO) activity and higher peroxidase (POD) activity than the controls. These results suggest that NCP may be a useful technique to reduce fruit decay and maintain quality in kiwifruits during postharvest storage.

SEASONAL PATTERN OF ACCUMULATION OF NUTRIENTS BY KIWIFRUIT 'HAYWARD' IN ACID SOILS OF NORTHERN PORTUGAL

Kiwifruit production in Spain and Portugal is mainly developed on acid soils, where Ca supply to crops can be limited. Previous surveys in the same area concluded a widespread lack of Ca in leaves and kiwifruits; and, it is well established this nutrient is of utmost importance for fruit quality. The aim of this work is to record the changes in concentration, distribution and quantity of macronutrients in leaves and fruits and to report the effects of foliar fertilization in a high-producing orchard representative of acid soils. The experiment was conducted in Portugal on mature kiwifruit plants, weekly fertigated and alternatively supplied with foliar fertilization. Leaves and fruits analyzed for mineral concentration were sampled respectively four times and eight times from fruit set up to harvest, recording fresh and dry weight accumulation at the same time. Results showed that N and K accumulated by the fruit increased linearly through the entire growing season whereas the rate of Ca accumulation showed a sigmoid pattern, reaching its peak ten weeks after fruit set. There was a positive response to fertilization on leaf concentration of K, Ca, Mg and dry weight accumulation but a negative relationship with N concentration. This direct relationship was maintained for fruit N and K, whereas Ca and Mg was inversely related to foliar application. It seems that the more vigorous growth induced by additional fertilization reduced the Ca supply to fruit. The significance of the first weeks of fruit development on final Ca accumulation is also clearly stated.

Cysteine proteinase inhibitor Act d 4 is a functional allergen contributing to the clinical symptoms of kiwifruit allergy

Kiwifruit has become a frequent cause of fruit allergy in the recent years. The molecular basis of type I hypersensitivity to kiwifruit is attributed to 11 IUIS allergens, with Act d 1, Act d 2 and Act d 5 characterized in extenso. Evaluation of the allergenic properties of Act d 4, a cysteine proteinase inhibitor from green kiwifruit (Actinidia deliciosa) was performed in this study. Identity of the purified glycoprotein was determined by Edman degradation and by mass fingerprint whereby more than 90% of the primary structure of the mature kiwifruit cystatin was confirmed. Using MALDI TOF analysis, molecular masses of 10902.5 and 11055.2 Da were detected for Act d 4, respectively. Positive skin prick reactivity with Act d 4 was induced in three kiwifruit allergic patients, as well as the upregulation of CD63 and CD203c molecules in the basophile activation assay. The IgE reactivity was detected in dot blot analysis while Western blot analysis was negative using sera from six kiwifruit patients, suggesting the presence of conformational IgE epitopes on the Act d 4 molecule. As activator of effector cells in type I hypersensitivity Act d 4 is a functional allergen contributing to the clinical symptoms of kiwifruit allergy.

Flowering of kiwifruit (Actinidia deliciosa) is reduced by long photoperiods

Mature kiwifruit (Actinidia deliciosa ’Hayward') vines grown under standard orchard management were exposed to 16‐h photoperiods from the longest day in summer until after leaf fall in autumn. Photoperiod extension was achieved with tungsten halogen lamps that produced 2–8 μmols m−2 s−1 photosynthetically active radiation. Long day treatments did not affect fruit dry matter or fruit weight at harvest during the growing season that the treatments were applied or during the following growing season. However, flowering was reduced by 22% during the spring following treatment application. As this reduction in flowering was not accompanied by a decrease in budbreak, the long day effect is not consistent with a delay in the onset of winter chilling. It is suggested therefore, that the observed reduction in flowering may be because of a diminution of floral evocation.

An open cuvette for heating individual fruits on kiwifruit vines

SummaryA set of cuvettes that heat individual fruits on a kiwifruit has been constructed. This apparatus will be used to determine how fruit characteristics are affected by temperature at various stages of fruit growth. The system consists of 25 cylindrical cuvettes each of which can be fitted around a single kiwifruit while it was still attached to a vine in the field. The cuvettes have no top or bottom, so air can move freely through them. Each cuvette is fitted with a 10 watt heating element that radiantly heats the fruit. A datalogger monitors cuvette temperatures and turns the heaters on and off via a multi channel controller. During a 5 d test period heated fruit were maintained at 4.5K ±0.1 (SD) above the temperature of ambient fruit. The cuvette system was tested on mature kiwifruit vines (Actinidia deliciosa (A. Chev.) C.F. Liang et A.R. Ferguson) for 48 d up to harvest. Heating increased the fresh weight and dry-matter content of fruit while delaying the rise in soluble solids concentration. The technique is useful for defining how fruit characteristics change with temperature. However, because only a small proportion of the fruit on a vine are heated, considerable caution is needed when interpreting results.

Purification and characterization of phytocystatins from kiwifruit cortex and seeds

Kiwifruit cysteine proteinase inhibitors (KCPIs) were purified from the cortex and seeds of kiwifruit after inactivation of the abundant cortex cysteine proteinase actinidain. One major (KCPI1) and four minor cystatins were identified from Actinidia deliciosa ripe mature kiwifruit cortex as well as a seed KCPI from A. chinensis. The predominant cortex cystatin, KCPI1, inhibited clan CA, family C1 (papain family) cysteine proteinases (papain, chymopapain, bromelain, ficin, human cathepsins B, H and L, actinidain and the house dust mite endopeptidase 1), while cysteine proteinases belonging to other families, [clostripain (C11), streptopain (C10) and calpain (C2)] were not inhibited. Inhibition constants (KI) ranged between 0.001 nM for cathepsin L and 0.98 nM for endopeptidase 1. The KI (14 nM) for KCPI1 inhibiting actinidain is at least 2 orders of magnitude higher than for other plant proteinases measured. The cortex KCPI1 and a seed KCPI purified from seeds had the same N-terminal sequence (VAAGGWRPIESLNSAEVQDV). BLAST-matching the peptide sequence against an in-house generated Actinidia EST database, identified 81 cDNAs that exactly matched the measured KCPI1 peptide sequence. Peptide sequences of two other cortex KCPIs each exactly matched a predicted peptide sequence of a cDNA from kiwifruit. The predicted peptide sequence of KCPI1 of 116 amino acids encodes a signal peptide and does not contain cysteine. Without the signal peptide (mature protein), KCPI1 has a molecular mass of ∼11 kDa, possesses the consensus sequence characteristic for the phytocystatins and shows the highest homology to a cystatin from Citrus×paradisi (52% identity). This is the first report of phytocystatins from the Ericales.

MODELLING THE RELATION BETWEEN ETHYLENE PRODUCTION RATE, RESPIRATION RATE AND THEIR INFLUENCE ON CLIMACTERIC AND NON-CLIMACTERIC FRUITS

Ethylene affects the metabolism of fruits on different levels. The definition of a closed packaging system for fruits includes the determination of the required O-2-permeability, CO2-permeability and ethylene permeability/ethylene adsorption rate of the packaging film. Consequently, to package a certain type of fruit in a specific package configuration, the relation between the ethylene production rate (at the optimal ripeness stage for packaging) and the respiration rate, with changing O-2 concentration, has to be established. For this purpose the Michaelis-Menten type model, describing the influence of O-2 on the respiration rate, was extended with an extra equation for the ethylene production rate. Experimental data on gas exchange were analysed using WEST (Hemmis N.V., Kortrijk, Belgium) modelling and simulation software. A clear linear relation was found between the ethylene production rate and the respiration rate (R-2 ranging from 0.8 to 1). It is, in our knowledge, the first time that such a relation was described. Moreover, analysis from the data revealed that for most investigated ethylene producing fruits, the ethylene production rate reached zero before aerobic respiration was stopped. The proposed model was made for commercially mature avocado, banana, mango, kiwi, nectarine, strawberry, raspberry, white grape and red currant fruit and illustrated with data of banana, nectarine, raspberry, avocado and kiwi fruit.

Systemic acquired resistance to Sclerotinia sclerotiorum in kiwifruit vines

Systemic acquired resistance (SAR) to Sclerotinia sclerotiorum was induced in mature kiwifruit vines after localized treatment with 0.2m M salicylic acid (SA) or previous inoculation with the same pathogen. SAR was expressed in adjacent untreated leaves as a reduction in lesion diameter. SA and the pre-inoculation treatment each induced significant resistance (c. 35 and 25% reduction, respectively) in the adjacent leaves in the direction of the trunk. However no effect was seen in the adjacent leaves in the direction of the shoot tip. Radiolabel from locally applied14C-SA moved into the shoot and towards the trunk without accumulating in the adjacent leaves. This suggests that SA was not the primary systemic signal for SAR. Induction of SAR by S. sclerotiorum was preceded by endogenous accumulation of SA in treated and adjacent leaves. Free SA increased by three-fold after 24h in the inoculated leaf and by two-fold in the adjacent leaves after 96h. However, PAL activity did not increase locally until 48h post-inoculation and remained unchanged throughout the experiment in adjacent leaves. Therefore the signal promoting SA accumulation must either operate downstream of PAL in the SA biosynthetic pathway, or produce SA by an independent mechanism, such as the hydrolysis of stored conjugated SA.

Carbon Supply From Starch Reserves to Spring Growth: Modelling Spatial Patterns in Kiwifruit Canes

The remobilization and transport of reserve carbon from a kiwifruit (Actinidia deliciosa)cane to developing axillary shoots was modelled using a simple pool structure and mass flow process. Manipulative experiments with mature kiwifruit plants are compared with simulation results. The model uses detailed architectural information rather than explicit partitioning functions, achieving carbon partitioning as emergent behaviour of a spatial organization. The model successfully simulated shoot growth and starch distribution patterns.

Improvement in kiwifruit storage life caused by withholding early‐season irrigation

Abstract We investigated whether irrigation can affect the storage potential of kiwifruit (Actinidia deliciosa (A. Chev.) C.F. Liang et A.R. Ferguson). Two experiments were carried out on mature kiwifruit vines growing in a deep silt loam near Gisborne, New Zealand. Experiment 1 (1990/91) mainly compared the effects of irrigation applied to replace different fractions of the shortfall between the weekly totals of potential evapotranspiration and rainfall. It also included a treatment in which early‐season irrigation was withheld. Experiment 2 (1991/92) compared the effects of withholding irrigation at different times during the season. Fruit firmness was measured by penetrometer at intervals during storage. Withholding irrigation for the entire season improved fruit firmness during storage, but was accompanied by a significant depression in fruit size. Withholding irrigation until midsummer resulted in only mild water stress (fruit size was unaffected) but increased by c. 30 days the time taken for the firmness of stored fruit to decrease to 1 kgf or 0.2 MPa (the critical value for market acceptability). The mechanisms by which irrigation affected fruit storage properties are unclear.

Temporal variability and scaling behaviour in the fine‐root system of kiwifruit (Actinidia deliciosa)

ABSTRACTWe show that temporal variability in root populations can depend upon the scale of measurement (particularly the sampled soil volume). The presence of roots in a range of volumes of soil was studied using perspex tubes installed horizontally into the soil around three mature kiwifruit vines. Roots intercepting lines scored on the tubes were counted using a periscope. For small volumes of soil (c. 2–4 cm3) the root counts varied with time in a very irregular manner, and as the interval between measurements increased the autocorrelation between the measurements decayed rapidly. At about half of the locations monitored there was no significant autocorrelation between measurements 27 d apart. Linear interpolation in these time series was unreliable, and where the correlation dimension could be resolved it was usually non‐integer (suggesting chaotic behaviour). The time series measured at different locations were poorly correlated, indicating weak coordination. As the observed soil volume increased, the coordination between locations improved, the autocorrelation function increased, and linear interpolation errors decreased (although these remained substantial). Clearly there are considerable fundamental constraints on our ability to predict the root behaviour of kiwifruit vines at scales that are appropriate for mechanistic models of nutrient and water uptake. We discuss the need for a new conceptual model of the fine‐root systems of kiwifruit and similar species.

Seasonal Dynamics of Biomass and Mineral Nutrient Partitioning in Mature Kiwifruit Vines

The accumulation of dry matter plus macro- and micronutrients by various components of 6-year-old, field-grown kiwifruit vines (Actinidia deliciosa var. deliciosa cv. Hayward) was recorded over one season. Twenty vines were harvested periodically throughout the year and separated into perennial components (roots<20 mm diameter, structural roots, stump, stem, cordon, one-year-old fruiting wood) and current season's growth (non-fruiting shoots, laterals on fruiting wood, leaves and fruit). There was minimal seasonal variation (CVs<7%) in biomass change in perennial components of the vine

Seasonal variation in mineral composition of fine roots from field-grown kiwifruit vines

Abstract Seasonal variation in the concentration of macronutrients and micronutrients in fine roots (<2 mm diameter) of mature kiwifruit (Actinidia deliciosa var. deliciosa) vines were sampled regularly over 1 year. For the majority of elements, concentrations exhibited a sinusoidal pattern of change, with a seasonal minimum 1–13 weeks after fruitset, and a seasonal maximum, within 12 weeks of budbreak. Concentrations thus declined from around budbreak until after fruitset, thee began rising again before harvest, and into winter. Exceptions were calcium and iron, which fluctuated randomly about a constant value throughout the season, and magnesium and boron, which had two maxima (instead of one) between harvest and budbreak. Measurements were compared with those from other woody tree crops, and the potential for the fine root system to supply nutrient to new season's growth is discussed.

Vegetative and reproductive behaviour of kiwifruit as related to cane length

Abstract In southern Italy (Bari, lat. 41°07′) mature kiwifruit vines (Actinidia deliciosa (A. Chev.) C.F. Liang et A.R. Ferguson cv. Hayward) on pergolas were subjected to different winter pruning treatments over 3 consecutive years (1986–88) in order to study the effects of cane length on vegetative and reproductive behaviour. Three treatments were achieved by pruning canes to 6, 12, and 18 buds, and cane numbers were adjusted to leave the same number of buds (400 ± 30) on each vine. The data collected showed that: (1) the mean percentage budbreak decreased as cane length increased; (2) the budbreak period in plants with short canes was 8.7 days, whereas with long canes it was 3.7 days; (3) the number of fruits per winter bud ranged from 1.5 (canes with 6 buds) to 2.6 (canes with 12 buds); (4) the mean fruit weight was 92.9 g in plants with short canes (6 buds each), 88.5 g in plants with 12 buds/cane, and 81.5 g in those with 18 buds/cane; (5) at winter pruning the mean weight of woody material removed...

Effect of oxygen supply and temperature at the root on the physiology of kiwifruit vines

SummaryA severe leaf disorder currently affects kiwifruit vines (Actinidia deliciosa var. deliciosa) in New Zealand and a number of other countries. The symptoms, which develop in mid‐summer, include interveinal chlorosis, development of necrolic areas on the leaf and eventual leaf death. Field observations strongly indicated the involvement of the root system. The present study investigated the extent to which temperature and oxygen supply at the root influenced the physiology of kiwifruit vines.Maximum root growth occurred at 20 °C, while temperatures in excess of 25 °C reduced growth. Shoot growth was also reduced by root temperatures above 20 °C. No obvious leaf symptoms developed on the vines affected by the high temperatures. Below 20 °C there was a marked reduction in growth with little or no growth occurring at 10 °C. While soil temperature can be expected to influence root growth per se, it would appear unlikely that it directly controls the seasonal pattern of root growth or greatly influences the physiology of the leaf.This study showed kiwifruit vines are not well adapted to tolerate low concentrations of oxygen in their root zone. Growth was substantially reduced when the supply of oxygen to the roots was reduced. The extent of the reduction was proportional to the number of hours per day the vines were without aeration. Root growth was particularly affected. Distinctive leaf symptoms appeared on all oxygen‐stressed vines and included the sudden appearance of large necrotic areas on the older leaves, sometimes preceded by an interveinal chlorosis. Measurement of the porosity of the roots indicated that the average air space between the tightly packed cells accounted for 2% or less of the total root volume. There was no obvious change in root porosity with decreasing oxygen supply or difference between the solution grown vines and vines from the field.Decreasing the supply of oxygen to the roots resulted in rapid reduction in the stomatal conductance of the leaves and the virtual elimination of the diurnal pattern. Associated with the decrease m the stomatal conductance was a marked increase in the maximum daily temperature of the leaves compared to the control vines. The difference between the two treatments increased with time. An estimate of the rate of consumption of oxygen per unit length of root (9.1 × 10−10 mol m−1 s −1) suggests that a mature kiwifruit vine could deplete the oxygen supply in a well aerated soil to an anoxic condition in about 5 hours. The relatively high consumption of oxygen coupled with the low porosity of the roots ensures that even short periods of low concentrations of oxygen in the root zone will seriously affect the physiology and growth of kiwifruit vines. It was concluded that poor aeration of the root system is likely to be a major factor in the incidence of the leaf disorder currently affecting kiwifruit vines in a number of countries.

Effect of increased preharvest temperature on fruit quality of kiwifruit(Actinidia deliciosa)

Relocatable greenhouses were used to increase the air temperature around mature kiwifruit vines 3–4 degrees C above ambient temperature during the period of fruit maturation on the vine. Fruit grow...

Modelling the economic consequences of potential management changes in a mature kiwifruit orchard in New Zealand

A mathematical model simulating the growth and harvesting of kiwifruit is described. The model has been used to investigate the economic implications of changes in crop loading, winter pruning intensity, pollination method and water management. It is concluded that for mature vines, the optimum crop load is about 70 fruit m −2 (1650 fruit per vine). However, economic success may depend just as much on improvements in bud break, pollination and water management. In particular, developments in artificial methods of pollination and the use of the growth regulator, hydrogen cyanamide, are projected to potentially improve yields and profits significantly. Replacing natural by artificial shelter is also likely to be cost effective, but whether investing in irrigation is profitable depends on local circumstances. However, the results from the model must be interpreted with caution. It has been tested against a limited data set and before it can be used with confidence, further experimental work is needed to confirm its findings.

Temperature studies on kiwifruit vines using relocatable greenhouses

Abstract A set of eight relocatable greenhouses has been built for studies of temperature effects on mature kiwifruit vines (Actirddia deliciosa (A. Chev.) C. F. Liang et A. R. Ferguson) growing in a typical orchard. Each greenhouse covers one half of a vine planted at 6 m within-row spacing on a T-bar trellis. Temperatures within the greenhouses are maintained at a constant differential above ambient air temperature. Details of the construction, operation, and performance of the greenhouses are provided. In an initial experiment carried out in spring 1985, the mean air temperature was increased by 0.7° C or 4.9° C for 41 days. At the higher temperature, bud burst was advanced by 7 days and full bloom by 14 days. In the wanner greenhouses, growth of the apical shoot was increased and the percentage of shoots which produced flowers was reduced. An interaction between the warmed and untreated halves of the vines was observed.

The effect of a pre-harvest treatment with Ethrel on the starch content of kiwifruit

Mature kiwifruit vines were sprayed with 6 mg l −1 Ethrel (active chemical ethephon 48%) at a fruit maturity of 4.8% soluble solids (SS) concentration. Fruit were harvested from treated and control vines at intervals until treated fruit reached at least 6.2% SS. After harvest the fruit were sub-divided into blossom-end, middle and stem-end zones of three tissue types, and analysed for starch content. Treated fruit had higher SS concentrations and were softer than control fruit. Ethrel-treated fruit from the final harvest had a higher sugar concentration than control fruit. The immediate response of kiwifruit to Ethrel treatment on the vine was to reduce starch accumulation in the core of the fruit, in particular at the stem end. Later, starch degradation at the blossom end of the fruit was promoted.

Seasonal accumulation of mineral nutrients by kiwifruit 2. Fruit

SUMMARYChanges in the concentration, distribution and quantity of macro‐ and micronutrients in the skin and flesh of fruit from 30 mature kiwifruit vines (Actinidia deliciosa var. deliciosa cv. Hayward) were recorded over a growing season in two high‐producing orchards.The concentration of copper, iron, nitrogen, phosphorus, potassium, sulphur and zinc in the flesh (seeds inclusive) declined sharply during the first 8 weeks of growth, reaching values which remained relatively constant, or declined only gradually, until harvest. For boron, calcium, magnesium and manganese flesh concentrations declined steadily throughout the season.Concentrations of nitrogen, phosphorus and potassium in the flesh were generally higher, and those of calcium manganese and zinc consistently lower, than corresponding concentrations in skin over the entire maturation period (23 weeks). Flesh concentrations of copper, iron, magnesium and sulphur exceeded those in the skin but only during the early stages of fruit development (up to 11 weeks after pollination). Boron concentrations in flesh and skin were similar during the season.The quantity of all nutrients increased throughout the season to be at a maximum by harvest The rate of accumulation of each element was greatest during the first 8 weeks of growth corresponding to the cell division phase of fruit development. There was 61–75% of the total calcium, manganese and zinc content taken up during this time, compared with 37–54% of the content of other nutrients. In the subsequent 15 weeks of development rates for nutrient accumulation declined. In the case of boron, calcium, magnesium, manganese, potassium and zinc there was minimal accumulation in the final 6 weeks prior to harvest.A mass How‐vascular transport model based on carbon and water influxes was used to predict the relative importance of phloem and xylem supply, and to partition nutrient accumulated by fruit over two time intervals; 2–8, and 8–17 weeks of growth. The model implies that where transpiration rates and phloem carbon concentrations are both high (i.e. approx. 6 ml water fruit−1 day−1 early in the season or 2 ml water mid season, and &gt; l00 mg C ml−1), transport of nutrients occurs primarily via phloem. The only exceptions under these conditions are calcium, manganese and zinc which are translocated preferentially in xylem.