Effect of agar,galactomannan and indole-butyric acid on in vitro rooting of the pear cultivar ‘Durondeau’ and apple rootstock cultivar ‘Marubakaido’

Summary

The influence of partial substitution of agar by galactomannans in culture media supplemented with different concentrations of indole-3-butyric acid (IBA) was studied on in vitro rooting of pear (Pyrus communis L.) cultivar ‘Durondeau’ and apple rootstock (Malus prunifolia Borkh.) cultivar ‘Marubakaido’. The galactomannans applied were obtained from Cassia fastuosa (cassia) and Cyamopsis tetragonolobus (guar gum) seeds. The results obtained with mixtures of agar and galactomannan (3 g l^–1 each) were compared with those from media solidified with a standard concentration of agar (6 g l^–1). The rooting of pear shoots was enhanced significantly in the presence of a mixture of agar plus cassia galactomannan compared to medium solidified with agar only. The modified media promoted a higher number of roots than the control, and increased the percentage of rooted shoots. A maximum of 84.8% rooting was obtained on half-strength MS medium (¹?2MS) supplemented with 0.49 µM IBA and solidified with a blend of agar plus cassia galactomannan. For the apple rootstock, only the number of roots per shoot was influenced significantly by the addition of galactomannan to the rooting medium. The highest number of roots per shoot was 16.67 on ¹?2MS medium gelled with a mixture of agar plus guar galactomannan supplemented with 4.90 µM IBA. The behaviour of the agar-galactomannan gel and the possibility of reduced costs when compared with systems containing only agar, suggest new biological and commercial applications for galactomannans.     

The effect of rootstock on yield and quality of ‘Mutsu’ apples

Summary

Yield and fruit quality parameters were studied during three years in a rootstock trial with ‘Mutsu’ apple. M.9 provided the highest total yield per tree as well as the highest quantity of intermediate and yellow fruit as compared with J.9, M.26 and B.9. Within similar colour categories, significant differences among rootstocks were also recorded for fruit starch degradation pattern (SDP), firmness, titratable acidity (TA), and soluble solids concentrations (SSC). Generally, the lowest SDP and highest fruit firmness was found in fruits from trees on rootstocks M.26 and B.9. The highest TA was found in fruits from trees on rootstocks M.26 and J.9 and the highest SSC in fruits from trees on rootstocks J.9 and B.9. However, considerable variations among years were also recorded. Correlation coefficients between rootstock and several yield and quality parameters revealed high correlation to SSC for green fruit and TA for medium and yellow fruit and some correlation to yield and number of fruits per tree.     

The effect of thermal environment,planting date and crown size on growth,development and yield of Fragaria × ananassa Duch. cv. Elsanta

Summary

The effects of environmental conditions, planting date and crown size on the timing, intensity and duration of cropping in the strawberry Fragaria × ananassa cv. Elsanta were investigated. Temperature was positively correlated with the rate of progress to fruiting whereas crown size had no effect. The first fruit reached harvest maturity after an estimated 891 day-degrees had elapsed above a base temperature of 2.9°C for waiting bed plants and 831 day-degrees above a base temperature of 2.4°C for cold stored plants. Temperature was negatively correlated with total yield, berry number and average berry weight for both waiting bed and cold stored plants of different crown sizes. Yield, berry number and average berry weight were positively correlated with crown size. The effect of temperature on the yield components appeared to be due to its effect on vegetative growth of the plants: canopy development was more limited at warmer temperatures. These results can be used to generate models to predict the effect of growth environment on cropping in strawberry.     

Agronomic,cytogenetic and molecular studies on hermaphroditism and self-compatibility in the Greek kiwifruit (Actinidia deliciosa) cultivar ‘Tsechelidis’

The development of hermaphrodite cultivars of kiwifruit (Actinidia deliciosa) to overcome dioecism is a priority for all breeding programmes, worldwide. If successful, the number of pollinators in the orchard could be reduced, allowing more space for reproductive vines. Hermaphroditism and the expression of self-compatibility were studied in A. deliciosa, using the new kiwifruit cultivar, ‘Tsechelidis’, as a model. This plant material was chosen for investigation as its female flowers produced viable pollen. The aim of the present study was to investigate the expression and nature of self-compatibility in ‘Tsechelidis’ and to evaluate its potential for breeding purposes. The expression of self-compatibility in ‘Tsechelidis’, between years, was investigated by controlled self-pollination of female flowers in the field and by microscopic studies on pollen viability in the laboratory. The commercial cultivar ‘Hayward’ and the pollinator ‘Matua’ were used as controls. Controlled self-pollination in the field confirmed that ‘Tsechelidis’ exhibited a degree of hermaphroditism and self-compatibility. Its flowers produced viable pollen and could set fruit of an acceptable size and quality after self-pollination, compared to open-pollinated fruit. The average fruit set percentage for ‘Tsechelidis’ was 34%, and ranked from 20% to 60% per vine, while the corresponding rate for ‘Hayward’ was only 4%. Microscopic studies on ‘Tsechelidis’ pollen revealed variations in pollen viability between different vines, which were even greater between different flowers on the same vine, ranging, in some cases, from 0% (absolutely sterile) to 70% (significantly fertile) per flower. Female control ‘Hayward’ vines were found to be practically sterile (0%), while male control ‘Matua’ vines were almost 100% fertile. The nature of self-compatibility in ‘Tsechelidis’ was investigated further by molecular analysis using the sex-linked sequence characterised amplified region (SCAR) markers, SmX, SmY, and SmY1, and by single nucleotide polymorphism (SNP) analysis. Hermaphroditism in ‘Tsechelidis’ was related to sex expression, as observed by SNP analysis, but complete genome mapping would be required to fully understand the mechanisms involved and to exploit this new genetic material for breeding purposes.     

The effect of defoliation on bulb production of tulip cultivar ‘Apeldoorn’

The distribution of dry matter between the different bulblets of tulip is not markedly influenced by either changes in leaf area or the position of the leaf. On the contrary, total bulb yield is strongly affected.A reduction factor, S_c, for incomplete soil coverage, when the leaf area index (LAI) is less than 4, normally used for evaluation of planting density effects, can also be used for the effects of defoliation on dry matter increase. This LAI-dependent factor shows a distinctly asymptotic pathway closely resembling

$\text{S}{}_{\mathrm{c}}\text{=}\text{P}{}_{\mathrm{act}}\text{P}{}_{\mathrm{pot}}\text{=1?e}{}^{\mathrm{?k1LAI}}$

where k ～ 0.6 and in which P_act is the actual measured dry weight increase and $\text{P}\text{?}{}_{\mathrm{<mtext>pot</mtext>}}$ the potential net dry weight increase for a closed canopy.     

Effects of the application of ‘cash’ on the growth,fruit yield,and nutrient status of tomato (Solanum lycopersicum L.) grown in reclaimed saline soil

Summary

The effects of ‘cash’ [a novel 2:5:1 (w/w/w) mixture of calcium sulphate, ground sunflower heads, and humic acid] as a soil amendment on the growth, fruit yield, and leaf nutrient status of tomato (Solanum lycopersicum L.) grown on reclaimed saline soil (EC = 9.4 dS m^–1) were investigated. A glasshouse experiment was performed in a completely randomised design with six treatments (0, 10, 20, 30, 40, or 50 g ‘cash’ kg^–1 soil) each with four replicates. The results indicated that ‘cash’ increased both the shoot dry weight (DW) plant^–1 and the root DW plant^–1, the free proline contents of leaves, and leaf chlorophyll contents. The use of ‘cash’ also increased the number of fruit plant^–1, fruit yield pot^–1, and fruit vitamin C contents, although total soluble solids (TSS) contents were not affected. The contents of nitrogen (N), potassium (K), and calcium (Ca), and the Ca:Na ratios of leaf tissues increased with all application rates of ‘cash’. Leaf phosphorus (P) contents showed no response to any applied level of ‘cash’. Leaf sodium (Na) contents declined gradually with an increase in the level of ‘cash’ applied to the soil. We concluded that ‘cash’ has a pronounced positive effect on the growth and fruit yield of tomato plants grown in reclaimed saline soil. ‘Cash’ therefore has the potential to be used as a soil amendment for vegetable crops such as tomato to overcome the adverse effects of salinity in newly-reclaimed soils.     

Rootstock influence on the incidence of rind breakdown in ‘Navelate’ sweet orange

Summary

The influence of three rootstocks, Carrizo citrange (Citrus sinensis (L.) Osb. × Poncirus trifoliata (L.) Raf.), Cleopatra mandarin (Citrus reshni Hort. ex Tanaka) and sour orange (Citrus aurantium L.) on the incidence and severity of rind breakdown in ‘Navelate’ sweet oranges was studied over seven years in four orchards. The proportion of affected fruit was greater in trees on Carrizo citrange (60% on an average) followed by Cleopatra mandarin (38%) and then on sour orange (9%). There were also significant differences in the severity of the disorder among rootstocks; more than 35% and 20% of fruit from trees on Carrizo citrange and Cleopatra mandarin, respectively, were rejected for commercialization, whereas only 4% of fruit on sour orange was rejected. Cryo-scanning electron microscopy (SEM) of fruit peduncles showed that average diameter of xylem vessel elements of peduncles of fruits on Carrizo citrange rootstock were 6% and 17% larger than those on Cleopatra mandarin and sour orange, respectively. Defoliation of fruit-bearing branches reduced water loss from fruit, maintained fruit peel water potential at a higher value than that of fruit on undefoliated branches and reduced the proportion and severity of affected fruit. It is concluded that fruit-tree water relationships are related to rind breakdown in ‘Navelate’ oranges and low fruit water content might be responsible for the disorder.     

The effect of boron upon leaf development and growth of the apple cultivar ‘Cox’s Orange Pippin’

One-year-old ‘Cox’s Orange Pippin’ trees planted in pots in sand culture in the spring of 1970 were (during the growing seasons of 1970–72) watered with nutrient solutions containing 0, 0.12, 0.23, 1.2, 3.5 or 7.0 mg boron per litre.

With increasing boron supply, the boron concentration of the leaves increased, the growth of current year’s shoots and to some extent of other plant parts increased, and summer leaf-fall and the occurrence of necrotic leaf spots (‘Cox spots’) decreased. The percentage of healthy leaves was greatest when boron in leaf dry matter was about 30 ppm.

In 1972 the trees with highest boron supply suffered from incipient boron toxicity and increased incidence of ‘Cox disease’ flowering was delayed, and the percentage of dead buds was increased. In the latter part of the summer the leaves curled upwards, turned purple and became brittle.     

Effects of crop load and time of thinning on the incidence of split pits,fruit yield,fruit quality,and leaf mineral contents in ‘Andross’ peach

Summary

The effects of light, moderate, or heavy thinning (5, 10, or 20 cm between fruit, respectively), conducted before (7 d or 15 d), during, or after (7 d or 15 d) pit hardening (PH), on the incidence of split pits, fruit yield, fruit quality characteristics, and leaf mineral contents, were studied in the canning peach (Prunus persica L. Batsch.) cultivar ‘Andross’ over two growing seasons. The percentage of fruit with split pits increased by 58.2% in heavily-thinned trees compared with moderately- or lightly-thinned trees, and by 22.9% for the earliest time of thinning (15 d before PH) compared with thinning during, or after PH. Fruit fresh weight (FW) was greater in moderately- and heavily-thinned trees compared with lightly-thinned trees, but yields were similar among the different crop-load treatments. The latest time of thinning (15 d after PH) also had a negative impact on yield at first harvest and on total yield, fruit FW, and delayed fruit ripening compared to thinning during, and 15 d before PH. Total anti-oxidant capacities and phenolic contents were usually greater in fruit from heavily-thinned compared with lightly- or moderately-thinned trees only when thinning was conducted during, or 15 d after PH. Moreover, anti-oxidant levels were highest in fruit from the earliest-thinned trees. There was no significant effect of crop load, or of time of thinning application treatment on fruit colour, or on the K, P, Fe, Mn, and Cu contents of leaf tissues. In conclusion, light or moderate thinning during PH resulted in minimal split pits during processing, and in optimal yields and fruit quality characteristics in the canning peach cultivar ‘Andross’.     

Effects of clonal rootstocks on ‘Hass’ avocado yield components,alternate bearing,and nutrition

Summary

Growth, yield, and leaf nutrient concentrations were measured in ‘Hass’ avocado (Persea americana Mill.) trees grown on one of ten clonally-propagated rootstocks (‘Borchard’, ‘D9’, ‘Duke 7’, G1033, G755A, G755B, G755C, ‘Thomas’, ‘Topa Topa’, or ‘Toro Canyon’) over a 10-year period in southern California. After 10 years, trees on ‘Borchard’ were larger than trees on all other rootstocks. Trees on all rootstocks displayed an alternate-bearing pattern, typical of avocado. Alternate-bearing was most pronounced in trees grafted onto ‘Topa Topa’ and ‘Toro Canyon’. Rootstocks in the G755 series had the lowest alternate-bearing index, but also had the lowest yields.Trees on ‘Duke 7’ and ‘Borchard’ had the highest cumulative yields, and trees on G755A, G755B, and G755C had the lowest yields. Differences in yield were due to differences in the number of fruit per tree, not individual fruit weight. When yield was evaluated in terms of canopy efficiency (kg fruit m^–3), no rootstock outperformed ‘Duke 7’, the industry standard rootstock. Leaf concentrations of all nutrients examined (N, P, K, Ca, Mg, S, Zn, Cl, Mn, B, Fe, and Cu) were within, or close to the recommended ranges. P, Ca, and S were higher, and Fe was lower in high-yielding years in all rootstocks.     

The influence of endothal and 6-benzyladenine on crop load and fruit quality of red ‘Delicious’ apple

Summary

Trial work over a two year period examined the aquatic herbicide endothal as a blossom thinner in conjunction with 6-benzyladenine (CyLex?) as a post-bloom thinner. The aim was to develop an effective thinning programme using endothal and CyLex?, to examine any interactions between the two chemicals, and to assess the impact of endothal on fruit quality. Time of application of endothal was shown to be critical in achieving a satisfactory level of thinning. Multiple applications of lower chemical rates were also successful, and may have potential to provide an effective programme for cultivars with long flowering periods, which are traditionally most difficult to thin. Addition of a surfactant to the spray mix significantly increased the thinning effect of endothal, resulting in severe over-thinning. This work has demonstrated that endothal is an effective thinner of red ‘Delicious’ apples. It is most effective when applied twice during the blossom period, the first application at 20% bloom and the second at 80% bloom. There is no advantage in increasing the concentration above 1.0 cm³ dm^-3 (v/v). Endothal can also be effectively combined in a programme with the post-bloom thinner CyLex? applied at 150 mg l”¹ at a spray volume of 12001 ha^-1. Addition of CyLex? to the spray programme has the added benefits of increasing fruit weight and size. Fruit sugar content and firmness were both increased by application of endothal. The greater the number of applications the higher the firmness and sugar content of the fruit. Both these findings are additional benefits to the thinning effect. Both pip number and fruit length/diameter ratio were slightly reduced by endothal. Cylex and some endothal treatments increased the incidence of fruit russet.     

The influence of fungicides and gibberellin (A4+7) applications on russet control of ‘Golden Delicious’ apple fruit

Summary

Various fungicides, gibberellins (A₄₁₇) and their mixtures were tested for the control of russet of ‘Golden Delicious’ apple fruit in the major apple-growing area in Israel. Four foliar applications of captan, metiram, the strobilurins kresoxim-methyl, trifloxystrobin, azoxystrobin, or the polyoxin B compound Polar from the green tip stage to the end of the petal fall stage gave similar reductions in russeting, compared with the controls, but none eliminated it. Tank mixtures of the gibberellins (A₄₁₇) Regulex and Perlan with captan, each at full rate, did not improve russet control, compared with each component alone at the same rate. Similarly, both captan and trifioxystrobin, and the gibberellin (A₄₁₇) Cytolin or their mixtures at full rates provided similar significant level of control of russet on fruit. Fruit in the upper part of the tree had significantly more russet than fruit in the lower part of the tree, regardless of treatment applied. In addition, russet was more severe on fruits of trees grown in the west side of the row, than those of trees grown on the east side. Data suggest that factors other than fungicides, which may act by reducing russet-inducing microorganisms, may be involved in russet development.     

Influence of rootstock on vegetative growth,fruit yield and quality in ‘Cuore di Bue’, an heirloom tomato

Summary

Heirloom tomatoes (Solanum lycopersicum L.) such as ‘Cuore di Bue’ are highly appreciated by consumers for their outstanding quality and flavour. Nowadays, they are often grafted onto vigorous rootstocks in order to overcome several soil-borne diseases. The present study was conducted in 2007 and 2008 in Southern Italy. Plants of ‘Cuore di Bue’, an heirloom ‘oxheart’ tomato, were grown in a greenhouse either as non-grafted plants, or grafted onto two inter-specific (S. lycopersicum S. habrochaites) rootstocks (‘Beaufort F₁’ and ‘Maxifort F₁’) in order to evaluate their effects on vegetative growth, marketable yield, fruit quality, and the sensory properties of ‘Cuore di Bue’ tomato fruit. Growth analysis revealed that ‘Maxifort F₁’ enhanced plant growth, particularly in terms of leaf area and leaf fresh weight. Grafted plants had higher leaf area ratios (by 13%) and higher leaf dry weight fractions (by 18%) compared to non-grafted ‘Cuore di Bue’ plants. Marketable yields increased by 20 – 25% in grafted plants in both years. However, total soluble solids (TSS) contents, titratable acidity (TA), and TSS/TA ratios were not significantly affected by grafting.Vitamin C contents decreased by 14 – 20% in both years in the fruit of plants grafted onto either rootstock. The sensory profiles of fruit were not modified by grafting, although taste panelists expressed a higher preference for purchasing fruit from plants grafted onto ‘Maxifort F₁’. These results confirm that, when using the appropriate rootstock/scion combination, grafting can improve plant growth and the marketable yield of heirloom tomato fruit without reducing the sensory quality of the fruit or its biochemical parameters. However, grafting can reduce vitamin C contents and, thus, nutritional quality.     

The effects of Apogee® on shoot growth,secondary flowering,fire blight,fruit quality,yield and return bloom in ‘Bartlett’ pear growing in California

Summary

Apogee^® sprays were applied to mature ‘Bartlett’ pear (Pyrus communis L.) trees as single or multiple sprays during the growing seasons of 1999 to 2003 at concentrations of 420 g ha^–1 (125 mg ^–1) or 840 g ha^–1 (250 mg^–1): both reduced vegetative shoot growth. Two sprays of 840 g ha^–1 applied 3–3.5 weeks apart were most effective and reduced shoot growth by approximately 40%. An application made 2 d after fall bloom was ineffective and led to more vegetative shoot growth. Single sprays of Apogee^® made within 9–28 d after full bloom (DAFB) were equally effective in reducing vegetative shoot growth. Bourse shoot growth was reduced 43% by 3 April, 2001 (8 DAFB) treatment of 840 g ha^–1 when bourse and vegetative shoots ranged from 2.5 to 7.5 cm in length. Subsequent single applications of 840 g ha^–1 Apogee^® (on April 12 or 23, 2001) did not reduce bourse shoot growth significantly. Vegetative shoot growth was also reduced by 12% (9 d after treatment) and by 38% (approximately one month after treatment) by 840 g ha^–1 Apogee^® applied on 3 April, 2001, (8 DAFB). In 2002, bourse shoot growth was controlled most effectively by split applications (840 + 420 g ha^–1 or 840 2 g ha^–1, 9 April and 24 May) and by 840 g ha^–1 Apogee^®, applied at 2.5 to 7.5 cm shoot growth (9 April). These split applications, as well as girdling, decreased shoot strikes in 2002, the year after treatment. Split applications of 840 g ha^–1 Apogee^® made in April to early May were most effective in controlling both vegetative and bourse shoot growth in most years, although single applications of Apogee^® were effective in some years. Subsequent flushes of shoots tended to be controlled by split applications with the second application timed to the emergence of new shoots. Apogee^® was not consistently effective in reducing the incidence of Type I or Type V secondary flowers in these trials. Single or multiple sprays of Apogee^® had no measurable or consistent effect on return bloom, fruit size or shape, firmness, percentage soluble solids, or yield per tree over the period of these experiments. Apogee^® appears to have promise as a shoot growth control agent in ‘Bartlett’ pear growing in California, USA, without deleterious effects.     

Effects of drought on fruit set,yield and quality of custard apple (Annona spp. hybrid) ‘African Pride’ plants

Summary

Studies were conducted to evaluate the effects of drought during flowering for both container- and field-grown trees, and during fruit development for container-grown trees, on subsequent growth, flowering, yield and quality of the custard apple ‘African Pride’ in subtropical Australia. Moderate drought (ψ_L=–1.5 MPa) reduced shoot growth by 20–30% and increased the number of flowers per lateral by about 40% compared with well-watered controls due to reduced apical dominance and increased lateral branching. Overall fruit set was not adversely affected by drought. Drought also increased the number of fruit harvested per tree by 47% compared with well-watered controls. This response was mainly due to the increase in flower number per tree. Drought reduced average fruit size by 11% possibly due to effects on cell division in the first 4–6 weeks after fruit set or on net carbon assimilation. In summary, mild to moderate drought during the flowering period and fruit set increased flowering without adversely affecting fruit set, but decreased fruit size.     

Effects of different crop loads and thinning times on yield,fruit quality,and return bloom in Malus × domestica Borkh. ‘Elstar’

Summary

‘Elstar’ is the latest-maturing commercial apple cultivar grown in Norway, with high fruit quality when properly managed. In May 2006, an experiment with four different crop loads [2, 4 ,6, or 8 flowers or fruitlets cm^–2 trunk cross-sectional area (TCSA), respectively] was established at two different stages [first bloom (FB), or 20-mm diameter fruitlets] and compared to unthinned control trees. Fruit growth was measured on individual fruit for each treatment throughout the season at weekly intervals. Thinning at FB gave a significantly lower final percentage fruit set than thinning to the same cropping level at the 20-mm fruitlet stage. However, fruit weights and soluble solids contents (SSC) were significantly higher, and the background fruit colour improved when trees were thinned at FB. The final number of fruit at harvest was less than the amount established at FB, or at the 20-mm fruitlet stage. There were significant differences between treatments in final fruit numbers per TCSA, which reflected the different crop loads. Fruit weights and SSC values were highest with the lowest crop load, and decreased with increasing crop loads. There was also a strong crop-load effect on the extent of return bloom per tree in the subsequent year. Trees thinned at FB had significantly more flower clusters than those thinned at the 20-mm fruitlet stage of. Untreated control trees had the lowest number of flower clusters. The amount of return bloom declined with increasing crop load. Second year crop loads and fruit weights were highest when trees were thinned at FB to two or four apples cm^?2 TCSA in the previous year. Trees with the highest crop load had the lowest crop load in the following year. Fruit quality was generally high for all treatments.     

The effects of low temperatures on the vegetative growth and flowering of the primocane fruiting raspberry ‘Autumn Bliss’

Summary

The effects of low temperatures on subsequent vegetative growth and flowering in the raspberry ‘AutumnBliss’ were investigated. In the first experiment, a number of lifting dates were used to determine the seasonal pattern of dormancy and the effect of natural chilling on plant development. In the second, different durations of artificial chilling(0, 2, 4, 6, 8 and 10 weeks at 0?C) were combined with two lifting dates to investigate the effect of natural and artificial chilling. In these experiments, plants which received little chilling grew slowly and failed to develop beyond short rosettes of leaves but as chilling increased, the rate of vegetative growth increased. This coincided with a decline in the time toflowering. These two responses, however, were distinct. In a third experiment, the effect of vernalization of actively growing canes was tested in an attempt to separate the effects of cold on time to flowering, and on the removalof dormancy. The plants responded significantly to cold treatment and flowering was advanced, indicating a distinct vernalizing effect