Flower-bud formation and shoot growth in apple as affected by temperature

Under controlled conditions, 3-year old ‘Golden Delicious’ and ‘Cox's Orange Pippin’ trees were exposed to 2 temperatures (high: 24° and low: 17° or 19° C) in various treatments in a 4-month period starting at full bloom. In general, shoot growth was reduced at the low temperature. For ‘Golden Delicious’ flowering did not respond to the various treatments; in ‘Cox's Orange Pippin’ it was stimulated at the low temperature.A rise in temperature from 17° to 24° C seven weeks before harvest, given to ‘Cox's Orange Pippin’ trees kept at 17° C from full bloom, reduced flower-bud formation and stimulated growth. A similar temperature increase applied to trees maintained at 24° C for 4–5 weeks after full bloom favoured flower-bud formation, but did not affect growth.The inhibitory effect of the high temperature on flowering is discussed in terms of an increase of the plastochron under the influence of gibberellins produced by the growing shoot tips.     

起垄栽培对苹果根系构型的影响

以9年生寒富/山定子为试材,研究砂土地和粘土地起垄栽培对苹果根系构型的影响。结果表明,无论砂土地还是粘土地进行起垄栽培,根系主要分布于垄台空间以内;垂直深扎根系较少;整个空间内根系分布比较均匀,没有明显的层次;骨干根数量增多,毛细根量大。骨干根粗度一般在3 cm左右,很少发生5 cm以上的大型骨干根;根系分支级数下降,一般在3级左右;大部分骨干根上直接着生小型根组,毛细根与骨干根之间运输距离缩短。地上部表现树势强健,叶片肥大明亮,果实分布均匀。     

Post-transplant growth of five deciduous ordic tree species as affected by transplanting date and root pruning

Shoot growth and leaf surface area were recorded during three seasons subsequent to transplanting five deciduous street tree species in Norway: Acer platanoides L., Aesculus hippocastanum L., Prunus avium L., Sorbus aucuparia L. and Tilia x europaea L. ‘Pallida’. Trees were transplanted at four dates, early and late autumn (August 25^th and October 23^rd), and early and late spring (April 23^rd and May 5^th–19^th, depending on species), with two root ball diameters (3 and 5 times the stem circumference). Control trees were not transplanted. Shoot growth in all species, except S. aucuparia, was reduced by 38 to 86% of control trees and leaf surface area by 13 to 61% in the first season after transplanting. In A. platanoides and A. hippocastanum shoot growth was also reduced in the second season (71 and 81% respectively). All species except A. hippocastanum resumed pre-transplant growth in the third season. Early autumn transplanting was least favourable in all the species, resulting in delayed establishment as well as reduced shoot growth and leaf surface area. Early spring transplanting was found favorable for A. platanoides and P. avium, but unfavorable for S. aucuparia. The experiment confirmed that the larger root balls are preferred over smaller root balls.     

The influence of apical dominance on the in vitro multiplication of the rhizome of Alstroemeria

The effects of mechanical and chemical methods of removing or reducing apical dominance on the multiplication of Alstroemeria cultivars grown in vitro were assessed. Subculture of rhizome explants without aerial shoot or rhizome apices and of rhizome explants divided into single internodes with or without aerial shoots, significantly enhanced rhizome multiplication. Subculture of rhizome explants with only the aerial shoot or rhizome apices removed produced no significant differences. Addition of the plant growth regulators T1BA, thidiazuron, NAA, GA3 and paclobutrazol to culture media, with or without BAP, did not significantly change the numbers of lateral rhizomes, shoots or roots produced. Paclobutrazol, however, extensively changed explant morphology.     

Growth of Rhododendron cultivars as affected by temperature and light

Summary

The purpose of this study was to investigate the adaptation of four Rhododendron cultivars to contrasting light and temperature conditions. Two evergreen rhododendron cultivars and two deciduous azaleas were grown for 112 d under short day (14 h) and long day (20 h) photoperiods combined with temperatures of 15 and 24°C. Additionally, these cultivars were compared for daylength extension at 24°C/long day under two irradiation treatments (incandescent lamps and fluorescent tubular lamps). The number of flushes of growth increased with increasing photoperiod and temperature in both evergreen cultivars and in R. canadense; azalea #89132 made only one flush in all treatments. In the evergreen cultivars the number of leaves per shoot in the first flush did not differ significantly between treatments, indicating that this character was predetermined by conditions during bud development. The number of leaves in later flushes increased with increasing photoperiod and temperature. The elongation growth of most flushes was also enhanced by longer photoperiod and higher temperature. High irradiation during photoperiodic extension further enhanced the growth. Azalea #89132 made more flower buds under high than low irradiation. The two evergreen cultivars differed in their growth habit. ‘Pohjola’s Daughter’ tended to continue growth in long days or at very high temperatures, and is thus predicted to thrive best in a maritime or semi-maritime cool climate. ‘Helsinki University’ responded to short daylength by ceasing growth regardless of temperature, and could be expected to perform successfully also in continental climates at latitudes around 45° N. R. canadense seemed to do best in a cool climate, but azalea #89132 should in time acclimatize in all kinds of climates within the limits of this study.     

Sex expression in watermelon as affected by photoperiod and temperature

The effect of environmental factors on sex determination of flowers of watermelon (Citrullus lanatus) was studied under controlled conditions. Short days (8 h) and a day temperature of 27° C increased the tendency towards female flowers. Day length of 16 h and a day temperature of 32° C inhibited the development of female flowers.     

Growth of pot roses and post-harvest rate of water loss as affected by air humidity and temperature variations during growth under continuous light

The effect of diurnal variations in air humidity and temperature under continuous lighting period (LP) on growth, flowering and water loss were studied in two pot-rose cultivars.     

Seedling growth and chemical composition of three pistachio cultivars as affected by soil applied boron

Summary

The effects of six levels of B (0,10,20,30,40 and 50 (μg g^?1) on the growth and chemical composition of the three cvs Badami, Fandoghi and Kale-ghoochi were studied in an arid calcareous soil under glasshouse conditions. It seems that 0.31 μg B ml^?1 in the soil saturation extract was adequate for normal growth of ‘Badami’ and ‘Fandoghi’ seedlings. Consequently, their aerial growth was either unaffected or suppressed by B treatments. On the other hand, shoot growth of ‘Kale-ghoochi’ was increased by the first increments of B addition and markedly reduced at the highest B level. The toxic B levels in shoots required for growth suppression were 8.9, 38 and 95 μg g^?l for ‘Badami’, ‘Fandoghi’ and ‘Kale-ghoochi’, respectively. Further, the B levels in the soil saturation extract associated with retarded shoot growth were 0.37,0.61 and 1.5 μg ml^?1 for ‘Badami’, ‘Fandoghi’ and ‘Kale-ghoochi’, respectively, and those for root growth suppression were, 0.24, 0.20 and 0.43 μg ml^?1 respectively. Based on the results, ‘Badami’, ‘Fandoghi’ and ‘Kale-ghoochi’ could be considered as very sensitive, sensitive and semi-tolerant with respect to B toxicity.     

Partitioning of 14C-assimilate in Easter Lily as affected by growth stage and flower removal

Three weeks before anthesis, flower buds of Easter Lily plants received 47 and 12% of ¹⁴C translocated from Leaf 5 (upper) and 25 (middle), respectively, whereas the bulb received 5 and 52%, respectively. Flower bud removal increased the fraction in the bulb to 52% (Leaf 5) and 63% (Leaf 25). At anthesis, the flowers received 78% (Leaf 5) and 65% (Leaf 25) of translocated ¹⁴C-assimilate, nearly all of which was in the second flower which was still expanding. Less than 5% of the ¹⁴C from either leaf moved to the bulb in intact flowering plants, but upon flower removal, the bulb received 26 and 59% of the labelled assimilate from Leaf 5 and 25, respectively. Five weeks after anthesis, nearly 85% of the ¹⁴C-assimilate from either leaf was in the bulb. The fraction of ¹⁴C moving into the daughter bulb increased from less than 10%, 3 weeks before, to over 50%, 5 weeks after anthesis. Regardless of treatment, sink activity of the daughter scales was 2- to 12-fold higher than that of the mother scales. Although much of the current assimilate from the upper half of the intact lily shoot moves to flowers before anthesis, flower-bud removal is an effective way to increase carbon supply to the bulb.     

Gas exchange and antioxidant response of sweet pepper to foliar urea spray as affected by ambient temperature

This paper analyses the effect of different air temperatures (10, 20 and 30 °C) on the response of sweet pepper plants (Capsicum annuum L. cv. Herminio) to foliar urea applications after growing plants for 20 day with and without nitrogen (N) applied to the growing substrate. Leaf CO₂ assimilation, chlorophyll fluorescence, root respiration, lipid peroxidation and antioxidative enzymes were analysed. Spraying plants with urea increased leaf CO₂ assimilation of N-deficient plants when applied at 20 or 30 °C, compared with non-sprayed plants. When plants were sprayed with urea at 10 °C chlorophyll fluorescence of leaves was similar to that of plants that were supplied with full N in the nutrient solution. Root respiration was not affected by urea sprays whilst leaf NO₃⁻ concentration was increased by urea but only when it was sprayed at 10 or 20 °C. Lipid peroxidation and ascorbate peroxidase in N-deficient plants were reduced significantly by urea sprays, especially when plants were sprayed at 20 °C with N-limitation in the growing substrate. This study shows that N-limitation in the growing substrate induces a temperature-dependant increase in the activities of antioxidant enzymes in leaves of pepper and applications of foliar urea can be optimised, when applied at the appropriate temperature, to partly replace the N supplied to the roots of sweet pepper.     

Vegetative growth, flowering and leaf nutrient concentration of boronia as affected by nitrogen level and form

Boronia (Boronia megastigma Nees, family Rutaceae) is an Australian woody shrub, producing strongly scented flowers at nodes. Increasing N levels from 0 to 25 mM in the nutrient solution increased the production of nodes, lateral shoots from these nodes and further nodes on these lateral shoots. With the same level of N, the order of number of node and lateral shoot production by N form was: combined NH₄⁺plus NO₃⁻ > NH₄⁺alone > NO₃⁻ alone. This increase in the number of nodes subsequently translated into increased number of axils initiating flower buds and then into fully developed flowers. However, increasing N levels decreased the percentage of flower buds developing to anthesis and individual flower weight. These decreases were attributed to continued vegetative growth during flower development. Increasing N levels increased the leaf N concentration with the concentration in the order NH₄⁺ + NO₃⁻ > NH₄⁺ > NO₃⁻. Nitrogen form did not affect the leaf tissue concentration of P, K⁺, Ca²⁺ and Mg²⁺. At lower N levels, the concentrations of these nutrients in the leaf tissue were higher and may have reached toxic levels, causing toxicity symptoms on leaves. At higher N levels, the concentrations of these nutrients were diluted due to increased growth and no toxicity symptoms were produced.     

Maturity of apple cv. Elstar as affected by temperature during a six-week period following bloom

Summary

In two experiments under controlled conditions, the effect of temperature (16, 20 and 24°C, experiment 1; 16 and 22°C, experiment 2) during a six-week period immediately following bloom on the progress of ripening around the normal picking time was evaluated for fruits of cv. Elstar. After six weeks, the temperature in experiment 1 was kept at 20°C throughout. In experiment 2 the temperature was 22°C from week 6 to 14, and 16 or 22°C from week 14 to 22. Post-bloom temperature clearly affected the rate of fruit ripening as reflected in ethylene production, background colour, starch content, firmness and red blush, but these variates did not respond to the same degree. The effect of temperature late in the season on ripening (just during the maturation period) was almost absent when the post-bloom temperature was 16°C. However, when post-bloom temperature was 22°C, fruits were greener, firmer, contained more starch and showed more red blush at 16 than at 24°C given from week 14 to 22. The acid content at ripening was lower at the higher post-bloom temperatures. Irrespective of the post-bloom temperature, acid content was also reduced at the higher temperature given during the maturation period. The content of soluble solids showed no consistent pattern.     

Flowering and fruit set in cherimoya (Annona cherimola Mill.) as affected by the tree-training system

Summary

Management of flowering and fruit set are of prime importance in order to obtain high yields in cherimoya (Annona cherimola Mill.) due to floral dichogamy. This phenomenon is largely dependent on environmental conditions such as temperature, relative humidity, and light intensity, which usually make hand-pollination of flowers necessary in order to achieve acceptable levels of fruit set and yield. Nevertheless, these factors can be modified by means of the growing system. In this work, we studied the effects of two tree-training systems on the environment inside the canopy, on flowering, on pollination, and on fruit set in mature ‘Concha Lisa’ cherimoya trees. The open-centre vase training system (6 m 4 m) and the high-density slender-spindle (tunnel) training system (4 m 1 m) were used. The high-density tunnel training system increased the relative humidity, as well as reducing the temperature and the level of photosynthetically active radiation, inside the canopy, which resulted in an earlier onset of the male floral stage and in an extended maintenance of the highly-receptive female stages. This resulted in an overlap of the sexuallycompatible floral stages, thus increasing the incidence of natural cross-pollination and maintaining the viable, receptive sexual stages and pollen, over time, to improve hand-pollination.     

Sod establishment and turfgrass growth as affected by urea–formaldehyde resin foam soil amendment

Urea–formaldehyde resin foam (UFRF) has recently been introduced as a soil amendment for turfgrass culture. A field study was performed to evaluate the impact of UFRF on soil physical and chemical properties, sod establishment and turfgrass shoot and root growth. Treatments included a non-amended, sandy loam soil and the same soil amended with UFRF at a rate of 20% (v/v) incorporated into the upper 0.1 m of the substrate. Physical and chemical analyses of the two substrates involved the determination of bulk density, total porosity, air-filled porosity at 0.4 m, moisture release curve, pH and electrical conductivity. Turfgrass growth was determined through several measurements that included shoot growth rate, root growth rate and monitoring of three root architecture parameters namely, total root length, total root area and mean root diameter. Turfgrass establishment was evaluated by measuring the vertical force applied to detach the sod from the substrate.UFRF amendment did not influence pH and EC and provided minimal alterations (non-significant) in soil physical properties by slightly increasing total porosity, easily available water and air-filled porosity, and by reducing bulk density. The impact of UFRF amendment improved cumulative clipping yield in five sampling dates but root growth and sod establishment rate were better than the control only on one sampling date. There appears to be limited benefit in amending soil with UFRF.     

Root and shoot growth of newly-transplanted apple trees as affected by rootstock cultivar,defoliation and time after transplanting

Summary

An experiment with Malus demonstrated that a large proportion of the transplanted root system was lost through death and decomposition soon after transplanting in the open ground. Mortality of the roots was not influenced by the rootstock cultivars or by defoliation but increased significantly with time. In the first month, shoots of maiden trees of Malus transplanted in June when in-leaf grew, but roots did not. Subsequently, most of the new roots on the rootstock M.9 regenerated from the rootstock stem, whereas with MM.106 the old coarse roots (>2.0 mm diameter) initially present at planting were most important. Root growth occurred in concert with shoot growth such that a functional balance was maintained as shown by the existence of a constant root length:leaf area ratio over a large part of the growing season. Following transplanting, the trees appear to re-establish their optimal ‘functional’ ratio by way of a co-ordinating pattern of growth tending to correct any disturbance to the ratio resulting from transplanting. Defoliation in the early establishment phase caused only a temporary initial reduction in the root growth, but reduced all the shoot growth variables measured and increased the root length:leaf area ratio throughout the growing season.     

Growth,gas exchange,and nutrient status in pepper (Capsicum annuum L.) grown in recirculating nutrient solution as affected by salinity imposed to half of the root system

Pepper plants grown in recirculating nutrient solution were exposed to NaCl-salinity (60 mM NaCl, 8 dS m⁻¹) imposed either to the entire or to half of the root system and compared to plants supplied with a standard nutrient solution (1.9 dS m⁻¹). The saline solution was obtained by adding NaCl to the standard nutrient solution. In the split-root treatment, the root compartment not exposed to salinity was supplied with raw water (0.38 dS m⁻¹). Both the stem and the root dry weights were markedly restricted by salinity, irrespective of salinizing half or the entire root system. In the split-root treatment, the dry weight of the root compartment receiving raw water did not differ significantly from that exposed to salinity. The net photosynthesis and the leaf chlorophyll content were restricted by both salinity treatments, but the decrease was more marked when the entire root system was exposed to salinity. In contrast, the stomatal conductance and the transpiration rate were equally reduced, regardless of salinizing the entire or part of the root system. The leaf Na and Cl concentrations were raised by the NaCl-salinity, but only in one sampling date the increase was significantly higher when the entire root zone was exposed to salinity, as compared with salinization of half of the root system. Salinity reduced significantly the leaf K, Ca, and Mg uptake but not to levels that could cause nutrient deficiencies. These results indicate that pepper is susceptible to high salinity, predominantly due to reduced stomatal conductance. However, after long-term exposure to salinity the growth may be suppressed due also to inhibition of photosynthesis at chloroplast level. The adverse effects of high NaCl-salinity are hardly mitigated when only a part of the root system is salinized, which indicates that the response is governed by root exposure to high NaCl concentrations and not by inefficiency of the roots to take up water.     

Effect of temperature on anthocyanin accumulation in apple fruit as affected by cultivar,stage of fruit ripening and bagging

Non-bagged and bagged apples of cvs Jonathan, Fuji, Jonagold and Tsugaru were harvested at different stages of ripening and irradiated with light at 15, 20 and 25°C. The changes in anthocyanin accumulation during ripening varied with temperature, cultivar and bagging or otherwise. In ‘Jonathan’, the optimum temperature for anthocyanin accumulation increased clearly from 15°C to 25°C in non-bagged and from 20°C to 25°C in bagged fruit as it ripened. In ‘Fuji’ and ‘Jonagold’, 20 and 15°C, respectively, were always the optimum for anthocyanin synthesis in non-bagged and bagged apples. In non-bagged and bagged ‘Tsugaru’, the optimum temperaturfe increased from 15°C to 20°C with ripening.     

Sweet-potato productivity as affected by recurrent use of vines as planting-material

Yield performances of apical shoot cuttings of sweet potato (Ipomoea batatas) obtained from crops raised 2 or 4 times recurrently through vines, were compared with those obtained from tubers. The recurrent use of vines as planting-material did not show any marked variation in market-grade tuber yield, but it significantly decreased vine yield and increased weevil infestation in tubers. Cultivars ‘Cross-4’, ‘RS-5’ differed significantly in performance