Performance of ‘Coscia’ pear (Pyrus communis) on seven rootstocks in a warm climate

Summary

The vegetative and reproductive performance of ‘Coscia’ pear (Pyrus communis L.) growing on seven rootstocks [OHF 69, OHF 97, OHF 513 and BP 1 (P. communis), clonal seedling (Davis AxB) of P. betulifolia, and quince BA 29 and EMA (Cydonia oblonga)] were compared over an 8-year period. The trial was conducted at the Experimental Orchard Farm Station in northern Israel, on a well-drained soil with pH 7.5. Trees were planted in December 1998 at a distance of 4.0 m 2.0 m, and trained with a central axis. The most vigorous trees were on P. betulifolia seedling, followed by BP 1 and the three OHF rootstocks (69, 97, 513). All the above rootstocks demonstrated greater vigour than quince BA 29 or EMA. The reason for this effect, at least in part, appeared to be the excellent water status (high midday stem water potential values) of trees on P. betulifolia in comparison with the other rootstocks. The highest cumulative yields per tree were harvested from trees on P. betulifolia and BP 1, followed by the three OHF rootstocks (69, 97, 513). However, the highest cumulative yield of large fruit (> 60 mm) was obtained from trees on P. betulifolia, followed by the OHF series and BP 1. The two quince rootstocks had the lowest cumulative yield, and the lowest yield of large fruit. A positive correlation was found between the vigour of the tree, as affected by the rootstock, and both total yield and fruit size. We conclude that, in a warm climate, yield efficiency is not the only parameter that should be taken into account, and building a strong tree for the weak scion cultivar is the first requirement for establishing an orchard. Fruit quality at harvest and during cold storage were examined for fruit from three rootstocks only. The highest soluble solids content values at harvest were obtained in fruit grown on quince EMA, compared to values for BP 1 and P. betulifolia fruit.     

Hormonal control of splitting in ‘Nova’ mandarin fruit

Fruit splitting, a physiological disorder of peel development in citrus, has been studied in terms of peel thickness and puncturing resistance in ‘Nova’ mandarins. Both features are negatively correlated with splitting. A mixture of G A, and 2,4-D reduced significantly the percentage of affected fruits. The best results were obtained with two applications at 60 and 30 d before the anticipated onset of the disorder. Calcium nitrate applications have similar effects, but were ineffective in orchards with a low natural incidence of splitting.     

Effects of different rootstocks and training systems on the mineral composition of ‘Delicious’ apple leaves

Leaf mineral composition as affected by different rootstocks, cultivars, training systems and their combinations was measured during 1987 and 1988. Trees on M.7 had significantly higher concentrations of N, P and Fe, whereas those on MM. 106 maintained higher values of K, Ca, Mg and Mn during both years. Between cultivars, Red ‘Delicious’ showed greater accumulation of N, P, Mg and Fe but K and Cu levels were found to be more in Starking ‘Delicious’. All mineral nutrients except Ca and Mg accumulated more in spindle-bush trained trees than those under modified central leader system. The Mineral composition of Starking ‘Delicious’ grafted on M.7 rootstock and trained as a spindle bush produced the best yield efficiency and fruit quality, and fell within the normal range.     

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.     

Nursery performance of ‘Cox’ apple trees with rootstocks of M.9 from either micropropagation or improved conventional propagation from micropropagated plants

Rootstocks of M.9 were produced either directly by micropropagation, by improved conventional propagation from apparently rejuvenated micropropagated plants or by conventional propagation throughout. These rootstocks were grown in the field for one year and then grafted with scions of ‘Cox’s Orange Pippin’. Performances of the composite trees were evaluated one year following grafting. Trees with rootstocks which came directly from micropropagation had many suckers and burrknots and usually had poorly developed scions. Trees with rootstocks from improved conventional propagation from micropropagated plants were similar to trees with rootstocks from conventional propagation throughout in being almost devoid of suckers and burrknots and having well developed scions.     

Root morphology and the effect of rootstocks on leaf nutrient acquisition of Kinnow mandarin (Citrus nobilis Loureiro × Citrus reticulata Blanco)

The study aimed to understand the root morphological character of 1 year old seedling rootstock of citrus genotypes viz., rough lemon, Karna Khatta, Carrizo citrange, Rangpur lime, Troyer citrange, Jatti Khatti and sour orange as well as to investigate the effect of these rootstocks on the leaf mineral composition of Kinnow. Root morphological traits showed significant genotypic variation. Rough lemon seedlings had a higher root length, projected area, surface area, volume and the number of forks. Sour orange was moderate rootstock of the 7 genotypes for most of the root morphological characters, while citrange rootstocks expressed poor root morphology. The rootstocks also imparted significant influence on the leaf mineral composition. Leaf K, Ca and Mg content was recorded maximum in plants grown on rough lemon seedling, while N, P, Fe, Zn, Mn and Cu concentration was higher on sour orange rootstock. Kinnow trees on Rangpur lime rootstock accumulated more Na in their leaf tissue, where as Troyer citrange restricted the accumulation of Na. Considering the root morphological characters and nutrient accumulation pattern, rough lemon and sour orange for areas free from tristeza virus could be suggested as alternative rootstocks for the studied Kinnow mandarin under similar ecological conditions.     

Mechanisms of salt stress tolerance in two rose rootstocks: Rosa chinensis ‘Major’ and R. rubiginosa

The responses of two rose rootstocks Rosa chinensis ‘Major’ and R. rubiginosa were investigated under salt stress. The distribution of chloride and sodium ions in all plant parts was determined. The salt treatments were applied through irrigation water containing 0, 5, 10, 20 and 30 mM NaCl. Necrosis on the leaves as a result of the NaCl treatments was observed with in rootstocks after two months. Leaf injury was more pronounced in R. chinensis ‘Major’ than R. rubiginosa. The rootstock R. rubiginosa showed a higher tolerance to the NaCl stress than R. chinensis ‘Major’. The survival of the plants under increased NaCl stress as well as the extent of leaf injury could be used in the determination of tolerance of the rose genotypes. The lower older leaves contained higher concentrations of Cl⁻ than the young upper leaves. Leaf samples had higher concentrations of Cl⁻ than stem samples taken from the same positions. The roots contained higher amounts of Cl⁻ than the stem samples. The plants accumulated higher amounts of Cl⁻ in comparison with Na⁺. The lower leaves of R. chinensis ‘Major’ had higher amounts of Na⁺ than in all other parts whereas R. rubiginosa had higher concentrations of Na⁺ in the roots than in all other parts.     

Changes in the competence of Quercus robur ‘Fastigiata’ to grow in vitro as affected by seedling rootstocks and differential pruning

Three physiologically distinct forms of the same genotype of Quercus robur ‘Fastigiata’, all derived from adult budwood, were identified following the growth of severely-pruned hedge plants grafted onto juvenile seedling rootstocks. Only explants from the form displaying the juvenile-like characteristic of over-winter leaf retention were capable of establishing sustainable cultures in vitro, although growth was not as rapid as those from a two year old seedling source. Pruning to release correlative inhibition of buds low on the scion framework produced vigorous shoot growth, but explants from these failed to show sustained growth in vitro. Withholding light from stockplants reduced excessive phenolic oxidation in explants taken from flushing unripe shoots, however, despite a beneficial effect on culture initiation, later growth was dependent upon the juvenile- or adult-like physiology of the original explant. A new medium was devised for this subject, which in addition to promoting growth generally, also stimulated the flushing of shoot apices. The relevance to in vitro culture of expression of juvenile habit in the stockplant is discussed.     

Effects of rate of establishment of storage conditions and ethylene removal on the storage performance of ‘Cox's Orange Pippin’ apples

The use of rapid establishment of temperature and CA storage conditions, as well as ethylene removal to reduce loss of firmness and ground colour, during storage of apples (Malus domestica Borkh, ‘Cox's Orange Pippin’) in <1% CO₂ + 1.25% O₂ at 3.5°C was investigated. Samples subjected to rapid establishment (RE) of storage conditions had a higher peel chlorophyll content after 5 months storage, but not after 8 months, than samples from containers where the conditions had been established at a rate typical of normal, well-maintained commercial stores (CR). RE samples were considered firmer than CR by a sensory panel in February but not in May, while penetrometer readings were the same on both occasions. RE samples which had additionally been subjected to a pre-harvest daminozide spray and ethylene removal during storage (LE) were firmer, had a higher peel chlorophyll content and, on the green parts of the surface, a lower Hunter “b” value in February than both CR and RE samples. The effects of LE on chlorophyll and ground colour were maintained until May, but in both February and May only the ground colour effect was maintained during a simulated marketing period of 14 days at 10°C in air following storage.     

Performance of ‘Discovery’ apple on M.9, M.26 and MM.106 rootstocks at two densities

Summary

The apple rootstocks M.9, M.26, and MM.106 were evaluated for their efficiency in bringing ‘Discovery’ apple trees into production. The experiment, carried out over a ten- year period compared two planting densities at 1666 and 3333 trees per ha. Tree vigour differences between rootstocks were measured in term of trunk growth, tree volume, weight of branches pruned off and final weight of the above-ground parts of the trees. Fruit production is presented both as total yield and as the weight of first class fruit. Fruit colour development is also shown. Cropping efficiency is calculated and presented in relation to the different vigour measurements. The results confirm that ‘Discovery’ is slow to come into production. M.9 was the most productive rootstock, but due to vigour differences MM.106 gave the same yields per tree, although the latter had the lower yield efficiency. M.26 performed poorly; its vigour was similar to M.9 but it produced the lowest yields.     

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.     

Effect of calcium supply on the physiology of fruit tissue in ‘Andesu’ netted melon

Summary

Fruit development and physiological traits were evaluated in ‘Andesu’ netted melon plants grown with and without calcium. Calcium exclusion accelerated softening, alcoholic fermentation and ethylene evolution of fruit compared with those supplied with calcium, but the opposite trend occurred with sucrose accumulation. A significant difference of calcium concentrations in the fruit between treatments was observed at the developing stage of the fruit (P<0.05), but the difference became smaller as fruit matured. In the mesocarp tissue from the basal hemisphere, calcium concentrations in the NaCl soluble fraction at ripe fruit stage differed significantly (P<0.05) between calcium treatments but no significant difference was detected in the inner mesocarp of the distal hemisphere. Calcium exclusion did not lead to the development of water-soaked symptoms in the mesocarp tissue of ripe fruit. Uronic acid concentrations in ionically bound pectin fraction did not differ between calcium treatments throughout fruit development. In covalently-bound pectin fraction, however, uronic acid concentration of ripe fruit was significantly lower in calcium-excluded plants than in calcium-supplied plants (P<0.05). Our results suggest that: first, accelerated fruit softening under calcium deficient conditions might result from promoted ethylene evolution rather than from the shortage of ionically-bound calcium in cell walls, second, calcium deficient condition does not necessarily lead to water-soaked symptoms in tissue of ‘Andesu’ melon fruit.     

Effect of inter-specific rootstocks on inorganic nutrient concentrations and fruit quality of ‘Hort16A’ kiwifruit (Actinidia chinensis Planch. var. chinensis)

Summary

Inorganic nutrient concentrations in leaves, xylem sap and fruit from ‘Hort16A’ kiwifruit (Actinidia chinensis Planch. var. chinensis) vines grafted onto eight inter-specific rootstocks [A. deliciosa (A. Chev.) C.F. Liang et A.R. Ferguson var. deliciosa; A. eriantha Benth.; A. hemsleyana×eriantha; A. macrosperma C.F. Liang; A. chrysantha Merr.; A. kolomikta (Maxim. et Rupr.) Maxim.; A. kolomikta (Maxim. et Rupr.) Maxim.; and A. polygama (Sieb. et Zucc.) Maxim.] were measured over three seasons. The nutrients analysed were phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), manganese (Mn), zinc (Zn) and boron (B). The objectives of these studies were to identify rootstocks which induced relatively high or low levels of nutrients in the scion cultivar, and to correlate the nutrient concentrations of the fruits with the incidence of storage disorders. The use of inter-specific clonal rootstocks had a substantial effect on the accumulation and concentration of inorganic nutrients in the fruit, leaves and stem sap of ‘Hort16A’ kiwifruit vines, but few consistent relationships were observed between fruit nutrient concentrations and the incidence of storage disorders. Vines on A. hemsleyana×eriantha accumulated high levels of P in their fruits, leaves and xylem sap, and high levels of Ca and Mg in their leaves and xylem sap. Vines on A. macrosperma accumulated high levels of K in their fruits and leaves. In general, vines on rootstocks with low vigour (i.e. A. polygama; A. kolomikta) accumulated relatively low levels of nutrients. The incidence of physiological pitting, a mineral-related storage disorder, was higher in fruit with lower Mg concentrations. While rootstock-induced differences in the vigour of vines had an important role in determining nutrient concentrations in fruits and leaves, some rootstocks clearly had a stronger inherent ability to absorb nutrients from the soil than others, independent of their effect on vine vigour.     

Effects of light on flavonoid and chlorogenic acid levels in the skin of ‘Jonagold’ apples

The objective of our work was to determine how fruit position on the tree affects flavonoid and chlorogenic acid contents. Light was measured at different positions within the canopy of 10-year-old ‘Jonagold’ apple trees on M.9 rootstock raised as slender spindles. Fruit from the top of the canopy contained the highest percentage of blush and the highest levels of cyanidin 3-galactoside (anthocyanin) and quercetin 3-glycosides, followed by fruit from the outside of the canopy, and then those from the canopy interior. There were no significant differences in the levels of catechins, phloridzin and chlorogenic acid among fruit from the different canopy positions. Light level was directly correlated with the levels of cyanidin 3-galactoside and quercetin 3-glycosides and with the percentage of blush in the fruit skin. Light in the interior of the canopy was poorer in UV-A, blue, green and red but richer in far-red light than at all other positions. Consequently, the FR/R ratio was much larger at the interior of the canopy than at all other positions. Both anthocyanin and quercetin 3-glycoside concentrations were clearly related to light level, and there was a critical FR/R ratio of about 1 below which no anthocyanin and only minimal quercetin 3-glycosides were formed.     

Determination of Salt Tolerance of ‘Camarosa’ and ‘Chandler’ Strawberries Grown in Perlite and Perlite

ABSTRACT

The effects of salt (NaCl) applications of various concentrations (0, 500, 1000 and 2000 mg/L) for 6 months on ‘Camarosa’ and ‘Chandler’ strawberry varieties grown in perlite and perlite:zeolite (1:1) media were investigated. In order to determine the salt resistance of varieties, the tolerance index (T.I.) and tolerance ratio (T.R.) were calculated on the basis of total chlorophyll content, and leaf and root dry weight. Also, the ability of keep in balance for potassium:sodium (K:Na) ratio in the aerial part and roots of plants were considered. It was determined that the highest T.I. and T.R. values calculated on the basis of leaf and root dry weight in cv. Camarosa in both media. Concerning the evaluations calculated on the basis of total chlorophyll, the results indicated that ‘Chandler’ is more resistant in perlite medium, ‘Camarosa’ is more resistant in perlite:zeolite (1:1) medium. K:Na ratio decreased with increasing salinity in both varieties. However, it was determined that K:Na ratio is higher in cv. Chandler, i.e., 0.83 than in cv. Camarosa (0.61). As a conclusion, it was determined that ‘Camarosa’ was more resistant to salt than ‘Chandler’. In addition, regarding the salt resistant performance of plants, perlite:zeolite (1:1) medium had more effective results than perlite.     

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 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.     

Preharvest applications of ethephon reduce superficial scald of ‘Fuji’ and ‘Granny Smith’ apples in storage

In 1989 and 1990, preharvest applications of 2-chloroethyl phosphonic acid (ethephon) at dosages from 50–400 mg 1’1 were applied to ‘Fuji’ and ‘Granny Smith’ apples. In 1989, the greatest reduction in scald after storage on both ‘Fuji’ and ‘Granny Smith’, relative to the untreated control resulted from applying 400 mg 1^?1 ethephon five weeks before harvest and was 45% and 55% of controls, respectively. On ‘Granny Smith’ 400 mg 1^? was also effective when applied three weeks before harvest. In 1990, preharvest applications of ethephon at either 200 or 400 mg 1^?1 reduced scald in both cultivars relative to the controls. Ethephon applied six weeks before harvest had no dosage effect on scald reduction after storage. There was no consistent effect on fruit maturity at harvest from any treatment in either year, and no effect on quality of fruit out of storage.