Deliciosa Var Research Articles

Temporal expression of effects of varying nitrogen supply on canopy growth, photosynthesis and fruit production for Actinidia deliciosa vines in the field

The effects of varying nitrogen supply on canopy leaf area, response of leaf net photosynthesis (An) to quantum flux density (Q), and fruit yields of kiwifruit vines (Actinidia deliciosa var. deliciosa) were examined in a two‐year field experiment. Vines were grown with 0, 250 or 750 kg N ha−1 year−1. The responses to nitrogen supply were compared with responses to shade, to examine the impact of reduced carbon assimilation on canopy leaf area and fruit yields. Nitrogen supply did not affect significantly any of the measured variables during the first season of the experiment. In the second season, canopy leaf area was reduced significantly where nitrogen supply was limited. The quantum efficiency of photosynthesis (φq) increased from 0. 03 mol CO2 mol−1 Q soon after leaf emergence to more than 0. 05 mol CO2 mol−1 Q during the middle of the growing season. The quantum saturated rate of An (Asat) also increased during the season, from 7–10 μmol CO2 m−2 s−1 soon after leaf emergence, to 15–20 (μmol CO2 m−2 s−1 during the middle of the growing season. φq and Asat increased significantly with nitrogen supply at all measurement times during the second season. For vines with high nitrogen, fruit yields in both seasons were similar, averaging 3. 05 kg m−2. Fruit yields in the second season were reduced significantly where nitrogen supply was limited, due to reduced fruit numbers. The relative effects of reduced leaf area and reduced leaf photosynthesis for carbon assimilation by nitrogen deficient vines were examined using a mathematical model of canopy photosynthesis for kiwifruit vines. Simulations of canopy photosynthesis indicated that effects on leaf area and on leaf photosynthesis were of similar importance in the overall effects of nitrogen deficiency on carbon assimilation. The effects of nitrogen supply on fruit numbers (i. e. flower development) preceded the measured effects on carbon assimilation, indicating that the nitrogen supply affected carbon partitioning to reserves in the first season.

Coconut milk enhancement of axillary shoot growth in vitro of kiwifruit

Abstract We sought to improve methods for micropropagation of kiwifruit (Actinidia deliciosa var. deliciosa) by enhanced axillary branching. We added 10% coconut milk to the treatment medium before autoclaving. We then measured shoot length, shoot freshweight, petiole length, number of single nodes, leaf area, and basal callus freshweight of shoots from the control and treatment media. The addition of 10% coconut milk significantly increased all six shoot parameters over 74 days of incubation. The number of single nodes produced, shoot length, petiole length, and leaf area were approximately doubled. Statistically significant linear correlations between basal callus freshweight and all shoot parameters measured, except leaf area, were found only in the coconut milk‐supplemented medium. This suggests the basal callus was acting as a pseudoroot.

Uptake of 15N by Kiwifruit Vines from Applications of Nitrogen Fertilizer Prior to Budbreak

Mature field-grown kiwifruit vines (Actinidia deliciosa var. deliciosa cv. Hayward) were fertilized with 15N-labelled fertilizer (ammonium sulphate, 10 atom % 15N, 50 kgN ha-1) to investigate the timing of uptake of fertilizer nitrogen (N) and its availability for new season's growth. Treatments were applied on four occasions, representing 2, 6, 10 and 14 weeks prior to budbreak. Samples of root, stem, cordon, fruiting cane, vacuum-extracted xylem sap, and new season's growth were collected at fortnightly interval from early winter until 2 months after budbreak.Two weeks after application of each treatment, 15N equivalent to an average of 7% of the applied label was recovered in root material. Although label was taken up by roots, there was no movement of 15N within the plant until about 1 month prior to budbreak when it was measured in the stem and cordon. Fertilizer nitrogen was not detected at the distal end of fruiting canes, and in new season's growth until 3-4 weeks after budbreak. Before budbreak, all nitrogen in the xylem sap was in amino forms. Nitrate appeared 4 weeks after budbreak, and although more enriched with 15N than the amino nitrogen, accounted for only 19% of the label. Eight weeks after budbreak, nitrate nitrogen accounted for 57% of the label.There were no major treatment effects of 15N on vines in either spring or at harvest, although enrichments in fruit and leaves from the earliest treatment tended to be less at the end of the season than those from the later applications.

Effect of nitrogen fertilisation on the free amino acid composition of kiwifruit during development and postharvest storage

Total fruit-nitrogen (N) and free amino acids were measured in fruit from mature field-grown kiwifruit ( Actinidia deliciosa var. deliciosa) vines during fruit development (25 weeks) and postharvest storage (20 weeks at 0°C) to determine the nature of compositional changes in these compounds, and the effect of fertiliser N on their concentration. Vines used in this study ranged from those which had never received applied N, to those receiving 1420 kg N ha −1 prior to commencement. Concentrations of total-N declined sharply during the first 12 weeks of growth, while free amino-N increased to a maximum at 9 weeks after fruit set. Free amino-N and fruit-N concentrations were both constant during the remainder of fruit development and storage. Free amino acids comprised as little as 13% and as much as 28–40% of total fruit-N during fruit development. About 26% of total-N was present as free amino-N during storage. Arginine, asparagine, glutamine and γ-aminobutyrate were the principal free acids, accounting for 67–85% of the total amino acid composition and 82–92% of the total amino-N at all stages of development and postharvest storage. Fruit-N concentrations generally increased with increasing N application and were highly correlated with arginine concentrations, but not consistently with those of any other amino acid. The relative distribution of amino acids in fruit was largely unaffected by N treatment, except in fruit from unfertilised vines, where smaller percentages of arginine and asparagine were compensated for by increased percentages of aspartate, glutamate and γ-aminobutyrate. During storage, the concentrations of a number of amino acids increased, including glutamine, leucine, isoleucine, serine, threonine and valine. Concentrations of the other major species were essentially stable, while those of alanine and aspartate declined during the latter stages of storage.

Measurement of canopy gas exchange of kiwifruit vines using a suite of whole-canopy cuvettes

A system for estimating net CO 2 assimilation and H 2O transpiration simultaneously for the canopies of four kiwifruit ( Actinidia deliciosa var. deliciosa) vines in the field is described. The canopy of each vine was enclosed in an open system gas exchange cuvette, with volume of ca 26 m 3 and basal floor area of ca 10 m 2. A computer-controlled sampling and logging system enabled one set of analytical instruments to be used for measuring sequentially the difference between ambient CO 2 and H 2O partial pressures and those within each cuvette. Air flowing into each cuvette was dispersed upwards and outwards, whereas air exited primarily through a slit in the floor. Average CO 2 partial pressures at various positions within the cuvette varied less than 0.05 μmol/mol during a 600 sec logging period, indicating adequate air mixing within the cuvette. The equilibrium time for canopy net CO 2 assimilation ( A) to respond fully to a large change in irradiance was about 120 sec. The equilibration time for the measurement system after changing cuvettes was about 60 sec. Real-time data analysis of gas exchange dynamics and graphical display of data enabled rapid decisions regarding system settings during a normal experimental period. On some days, large diel fluctuations in ambient CO 2 partial pressures caused significant short-term variability in measured differential CO 2 partial pressures, although long-term (e.g. 8 hr) integrals were valid. Effects of different canopy leaf areas on diel dynamics of net A and net H 2O transpiration ( E) were clearly illustrated. Mid-day declines of net A were also demonstrated.

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

Chemical composition of pollen from kiwifruit vines

Abstract The chemical composition of kiwifruit (Actinidia deliciosa var. deliciosa) pollen was examined using hand-collected samples from nine staminate clones—‘Matua’, ‘M51-M58’, and one pistillate cultivar (‘Hayward’). Measurements included: ash, minerals, ether-extractable lipid, total dietary fibre, extractable carbohydrates, protein amino acids, and free amino acids. There were no major compositional differences amongst the staminate clones. The ash, lipid, and fibre content of the sterile pistillate pollen, on the other hand, was greater, and the protein content lower, than that of the male clones. Nitrogen (N) (67.6), potassium (10.6), and phosphorus (10.0 g/kg dry weight (DW)) were the elements present in greatest concentration in staminate pollen, and N (24.3) and calcium (12.0 g/kg DW) in pistillate pollen. Zinc and iron were the principal trace elements in both instances. Fructose accounted for as much as 76% of the extractable carbohydrate, followed by glucose and minor amounts of sucrose. The...

Effect of environment and harvest date on maturation and ripening of kiwifruit in British Columbia

Kiwifruit (Actinidia deliciosa var. deliciosa ’Hayward’ (A. Chev.) C. F. Liang et A. R. Ferguson) were harvested periodically from 10 Oct. to 21 Dec, 1990 to monitor "on-the-vine" ripening in three environments (field; greenhouse, covered for the full season; greenhouse, covered until pollination and then uncovered). Fruits were also placed in 1 °C, 97% RH storage on 19 Oct., 22 Oct., 25 Oct., and 3 Nov. and sampled periodically to monitor their "in storage" ripening. Field-grown fruit remained firmer than greenhouse-grown fruit (both treatments) on the vine, and in storage for about 7 weeks following harvest. There was little difference in the harvest maturity date of fruits from the three growing environments. In storage, fruits showed no differences in soluble solids content (SSC), and tissue deterioration (as measured with firmness and chlorophyll fluorescence) due to growing environments. The peak SSC values attained by fruits harvested prior to reaching a SSC of 6.2% were significantly lower than for fruits harvested after the SSC had reached or surpassed 6.2%. Later-harvested fruits remained firmer in storage than those harvested earlier. Changes in the fruits’ SSC and firmness were similar whether on the vine or in storage; however, fluorescence decline was more rapid in storage.Key words: Actinidia deliciosa, soluble solids content, fruit firmness, post harvest, chloroplast, temperature

Somatic embryogenesis in leaves and leaf-derived protoplasts of Actinidia deliciosa var. deliciosa cv. Hayward (kiwifruit)

The obtention of embryogenic competence in Actinidia deliciosa var. deliciosa cv. Hayward is reported. Axillary buds from shoots submitted to cold (4°C) and starvation for 1.5 months, developed leaves with embryogenic competence. These leaves, cultured in darkness for 1.5 months on a medium containing zeatin as a sole growth regulator, originated compact structures from which embryos developed. The plating orientation and sectioning of leaves strongly affected the expression of the embryogenic potential. A selected fraction of the protoplasts isolated from these leaves was able to develop in an embryogenic way. The germination of the embryos is still only occasional.

Canopy photosynthesis and respiration of kiwifruit (Actinidia deliciosa var. deliciosa) vines growing in the field.

Net CO(2) assimilation (A) for canopies of kiwifruit (Actinidia deliciosa var. deliciosa) vines enclosed in a whole-canopy cuvette was measured continuously for three periods of 15-20 days during late summer, near Hamilton, New Zealand (latitude 38.2 degrees S). Canopy A showed an asymptotic response to incident radiation (PAR), saturating at about 1300 micromol m(-2) s(-1) for one vine and about 800 micromol m(-2) s(-1) for two other vines. Radiation interception at low solar angles and low leaf area apparently limited the response of A to PAR. Radiation saturated rates of A were 25-30 micromol CO(2) m(-2) s(-1) for one vine, and 12-18 micromol CO(2) m(-2) s(-1) for two other vines. At any PAR, canopy A was often lower in the afternoon than in the morning. Canopy respiration averaged 8.9 micromol CO(2) m(-2) s(-1) at 12 degrees C, but increased only 24-34% over the range 7-17 degrees C. Net daily C gains for the whole canopy, calculated as the temporal integral of A, ranged from -0.8 g C m(-2) for a cloudy day (PAR </= 450 micromol m(-2) s(-1)) to 6.2 g C m(-2) for a day with intermittent cloud. Measurements of gas exchange for single leaves in a leaf cuvette were used to examine the basis of the whole-canopy responses to environmental variables. Partial stomatal closure due to water stress apparently contributed to the afternoon depressions in A, although non-stomatal limitations may also have been involved.

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.

Cell Wall Dissolution in Ripening Kiwifruit (Actinidia deliciosa)

Pectic polysaccharides solubilized in vivo during ripening, were isolated using phenol, acetic acid, and water (PAW) from the outer pericarp of kiwifruit (Actinidia deliciosa [A. Chev.] C.F. Liang and A.R. Ferguson var deliciosa ;Hayward') before and after postharvest ethylene treatment. Insoluble polysaccharides of the cell wall materials (CWMs) were solubilized in vitro by chemical extraction with 0.05 molar cyclohexane-trans-1,2-diamine tetraacetate (CDTA), 0.05 molar Na(2)CO(3), 6 molar guanidinium thiocyanate, and 4 molar KOH. The Na(2)CO(3)-soluble fraction decreased by 26%, and the CDTA-soluble fraction increased by 54% 1 day after ethylene treatment. Concomitantly, an increase in the pectic polymer content of the PAW-soluble fraction occurred without loss of galactose from the cell wall. The molecular weight of the PAW-soluble pectic fraction 1 day after ethylene treatment was similar to that of the Na(2)CO(3)-soluble fraction before ethylene treatment. Four days after ethylene treatment, 60% of cell wall polyuronide was solubilized, and 50% of the galactose was lost from the CWM, but the degree of galactosylation and molecular weight of pectic polymers remaining in the CWMs did not decrease. The exception was the CDTA-soluble fraction which showed an apparent decrease in molecular weight during ripening. Concurrently, the PAW-soluble pectic fraction showed a 20-fold reduction in molecular weight. The results suggest that considerable solubilization of the pectic polymers occurred during ripening without changes to their primary structure or degree of polymerization. Following solubilization, the polymers then became susceptible to depolymerization and degalactosidation. Pectolytic enzymes such as endopolygalacturonase and beta-galactosidase were therefore implicated in the degradation of solubilized cell wall pectic polymers but not the initial solubilization of the bulk of the pectic polymers in vivo.

Identification of E‐Hex‐3‐enal as an important contributor to the off‐flavour aroma in kiwifruit juice

AbstractThe volatile components of the juice of kiwifruit (Actinidia deliciosa (A Chev) Liang et Ferguson var deliciosa cv Hayward) have been isolated by low temperature vacuum distillation followed by ether extraction of the aqueous distillate and by headspace sampling using Chromosorb 105 adsorption. Of the 73 compounds identified, E‐hex‐3‐enal has been shown to be a major contributor to the ‘old cut grass’ and ‘hay’ aroma notes found in kiwifruit juice. Several free carboxylic acids have also been identified as components of the volatiles.

Seasonal changes in photosynthetic capacity of leaves of kiwifruit (Actinidia deliciosa) vines

The seasonal trend of photosynthetic capacity of leaves of kiwifruit (Actinidia deliciosa var. deliciosa) vines growing in the field was examined, by measuring the response of net photosynthesis (A) to irradiance (PAR) at monthly intervals for leaves that emerged at different stages of the growing season. A climate controlled minicuvette system was used, to ensure constant environmental conditions, apart from the controlled changes in leaf irradiance. Responses of A to irradiance were described using asymptotic exponential curves, providing estimates of the radiation saturated rate of A (Asat), and the reponse of A to increasing incident PAR at low PAR levels (ϕi). The change in photosynthetic capacity with leaf age was similar for leaves emerging 1, 2, 3 or 4 months after bud burst. At 1 month after leaf emergence, when leaves were fully expanded, Asat was 9–11 μmol CO2 m−2 s−1. Maximum photosynthetic capacity was not attained until 3–5 months after leaf emergence, when Asat was 16–17 μmol CO2 m−2 s−1. The increasing photosynthetic capacity during 3–5 months after leaf emergence was closely related to concomitant changes in leaf N and chlorophyll contents. The possibility that N import to the leaf was a significant factor limiting the development of photosynthetic capacity is discussed.

Effect of Hydrogen Cyanamide on Amino Acid Profiles in Kiwifruit Buds during Budbreak

Buds, and resultant shoots, were collected from kiwifruit (Actinidia deliciosa [A. Chev.] CF Liang et AR Ferguson var deliciosa cv Hayward) vines from late autumn until late spring with and without hydrogen cyanamide treatment. Those samples were weighed and analyzed for total nitrogen and free amino acids. By 7 days after hydrogen cyanamide treatment, the amount of proline had risen to nearly one-quarter of the total amino acid pool in the treated buds and that proportion was maintained for at least 14 days before it declined. The maximum concentration detected in treated buds was 25.8 micromoles per gram dry weight, 6.6 times that detected in untreated buds. By 95 days after treatment, the relative amounts of proline were not significantly different.

Sex expression in fruiting male vines of kiwifruit

In three canes on each of five fruiting male kiwifruit vines (A. deliciosa var. deliciosa (A. Chev) Liang and Ferguson), staminate and bisexual flowers were interspersed, so that staminate, bisexual and mixed inflorescences were found. Further variation in inflorescence composition resulted from the abortion of flower buds prior to anthesis. These two sources of variation, in combination, resulted in 19 inflorescence patterns, which varied substantially in frequency among and within vines. Some tendencies were determined. In particular, most of the inflorescences had retained their terminal flower, whereas just over half had retained one or both primary lateral flowers, and in two-thirds of the inflorescences retaining a terminal flower, this was bisexual. The five vines ranged in bisexual flower frequency from 40% to 70%. Phenotypic Gender (P) estimates are given for each vine, based on the frequencies of staminate and bisexual flowers from three canes per vine. Flower development, lability in sex expression and the use of P estimates as part of a selection index in breeding for hermaphrodite kiwifruit cultivars are discussed.

Gender variation in Actinidia deliciosa, the kiwifruit

Flower and fruit characters were measured in ten female, five male and five fruiting male selections of A. deliciosa var deliciosa (A. Chev) Liang and Ferguson. Flowers from female vines had functional pistils, which contained many ovules. Stamens appeared to be fully developed but produced only empty pollen grains. Flowers from male vines had functional stamens that produced high percentages of pollen grains with stainable cytoplasmic contents. Pistils did not contain ovules and were generally small with vestigial styles. Fruiting male vines had both staminate and bisexual flowers. Staminate flowers were similar to those found on strictly male vines. Bisexual flowers produced ovules and stainable pollen. Pistils were smaller than in pistillate flowers. Although the three flower sexes differed in style length, ovary dimensions and ovules per carpel, staminate and bisexual flowers were similar in number of flowers per inflorescence, stamen filament length, pollen stainability, inflorescence rachis length and carpel number, and differed from pistillate flowers in these characters. The three flower sexes had similar sepal and petal numbers. The fruit of fruiting males were considerably smaller than those of females. Low ovule number appears to be the major factor limiting fruit size in the fruiting males studied. Prospects for developing hermaphroditic kiwifruit cultivars through breeding are discussed.

Influence of anions on the potassium status and productivity of kiwifruit (Actinidia deliciosa) vines

The effects of K fertiliser (160 kg ha-1) applied with Cl- or SO42- as the accompanying anion on the K nutrition of kiwifruit (Actinidia deliciosa var. deliciosa) were assessed in a field experiment, using vines with varying degrees of K deficiency. Leaf K concentrations in spring were significantly higher for vines receiving KCl, compared to those receiving K2SO4. This effect did not interact significantly with the degree of K deficiency, and persisted for about 6 weeks. Subsequently there was no significant difference between the leaf K concentrations for the vines receiving KCl or K2SO4. Applying K as KCl increased the leaf Cl concentration, especially in spring, while applying K as K2SO4 had no significant effect on the leaf S concentration at that time. These results implied a greater requirement for organic acid anions for K+ uptake from K2SO4 than from KCl, and the importance of organic acid anions for K+ uptake from different sources of K fertiliser is discussed. This transient effect of the accompanying anion on leaf K status was associated with large effects on flowering, and fruit yields were about 28% higher for plants receiving KCl rather than K2SO4.

Plant regeneration from protoplasts of long-term callus cultures of Actinidia deliciosa var. deliciosa cv. Hayword (Kiwifruit)

Plant regeneration of Actinidia deliciosa var. deliciosa cv. Hayword was obtained from protoplasts isolated from petiole derived long-term callus cultures. Protoplasts were cultured in liquid medium over agarose gelled medium. Regenerated green callus, plated on solid medium, could develop shoots that rooted spontaneously in hormone-less medium. The plants obtained are growing fast in soil and present a normal phenotype.

A genome-specific repeat sequence from kiwifruit (Actinidia deliciosa var. deliciosa)

Six members of a family of moderately repetitive DNA sequences from kiwifruit (Actinidia deliciosa var. deliciosa) have been cloned and characterized. The repeat family is composed of elements that have a unit length of 463 bp, are highly methylated, occur in tandem arrays of at least 50 kb in length, and constitute about 0.5% of the kiwifruit genome. Individual elements diverge in nucleotide sequence by up to 5%, which suggests that the repeat sequence is evolving rapidly. Homologous sequences were found in A. deliciosa var. chlorocarpa. The repeat sequence was not found under low stringency hybridization conditions in the diploid A. chinensis, the species most closely related to the hexaploid kiwifruit, or in eight other Actinidia species. However, homologous repeats were detected in a tetraploid species, A. chrysantha. The results provide the first molecular evidence to suggest that kiwifruit may be an allopolyploid species.