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1.
The new generation of seaweed extracts, such as Actiwave®, may represent a promising strategy to reduce the use of phytochemicals in agriculture. Actiwave® is a metabolic enhancer derived by the algae Ascophillum nodosum, but differently from some older seaweed extracts, it has a constant and balanced formulation containing kahydrin, alginic acid and betaines which synergistically contribute to the efficacy of the product. Actiwave® has been proposed to increase the mineral nutrient uptake and the abiotic stress tolerance. The aim of this work was to evaluate, under a multidisciplinary approach, the effect of the biostimulant on the vegetative and productive performances of strawberry plants grown on a lime inducing iron chlorosis substrate. This biostimulant increased the vegetative growth (10%), the leaf chlorophyll content (11%), the stomata density (6.5%), the photosynthetic rate and the fruit production (27%) and berry weight. The most significant result was the increase of the plant biomass: the shoot dry matter was increased up to 27% and root dry matter up to 76%. Finally, preliminary experiments showed that Actiwave® positively influenced also the root-associated microbial biocoenosis. These results are discussed in relation to the physiological and ecological mechanisms proposed to explain the beneficial effects of this seaweed extract. Finally, the effects of Actiwave® and sequestrene were significantly similar, thus showing that this biostimulant may represent an environmental-friendly substitute of the iron chelates.  相似文献   

2.
Control of regular cropping in apple is considered critical for fruit growers to ensure their economical sustainability. Irregular flowering can be mitigated by plant growth regulators thanks to their promotion or inhibition effects. In this study, responses of GA4+7 and ethephon on alternate bearing in ‘Golden Delicious’/M9 were examined. GA4+7 and ethephon were applied on the same trees during three consecutive years (2010–12). Flowering, yield, shoot growth, and also some fruit quality parameters were assessed. GA4+7 appeared to be more effectual to regulate alternate bearing. The alternate bearing index calculated with yield in successive years was high in control (0.91), moderate in ethephon (0.71), and low in GA4+7 treated trees (0.41). Modified alternate bearing index, based on cluster number, indicated moderate intensity in GA4+7 (0.53) and high intensity in the others. Although GA4+7 reduced crop density at about 50%, there was little variation in yield per tree and crop efficiency due to increasing of fruit size. GA4+7 did not increase shot length after establishment of equilibrium between vegetative and generative growth in 2012. Ethephon slightly reduced vegetative growth and relatively increased fruit size due to the decrease of fruit set.  相似文献   

3.
Summary

Losses of apple fruit due to sunburn damage under South African climatic conditions can reach up to 40% per annum for specific cultivars in certain years. Various approaches to reduce the incidence and severity of sunburn resulted in temporary effects but, at present, no single remedy is available to provide a significant and consistent reduction in sunburn damage on a commercial scale. ‘Golden Delicious’ apple trees that received both calcium (Ca) and boron (B) as foliar applications on a weekly basis, when applied from approx. 21 – 70 d after full bloom (DAFB), showed significantly less sunburn in two consecutive seasons (P = 0.0500 and P = 0.0247 respectively) than untreated control fruit, or treatments based on Ca alone. The minerals were applied as supplements of sugar-alcohol complexed with Ca and B, trading as Manni-Plex® Ca [10% (w/w) Ca] and Manni-Plex® B [3.3% (w/w) B], respectively. The mode of action by which the incidence of sunburn was reduced using combined sprays of Manni-Plex® Ca plus Manni-Plex® B remains to be elucidated.  相似文献   

4.
Ethephon and 2,4,5-T were used on ‘Imperial’ mandarin to study their effects on fruit thinning, fruit size, rind pigments and alternate bearing.Ethephon at 250 p.p.m. produced the largest and heaviest fruits. Pigment levels were not affected by 2,4,5-T, but ethephon increased carotenoids and reduced chlorophyll a and b levels. The effectiveness of a colouring agent seems to be related to its ability to reduce both levels of chlorophyll a and b provided that carotenoid levels do not decrease.Treated trees exhibited less tendency towards alternate bearing than control trees. Ethephon had a greater thinning-effect than 2,4,5-T. It also evened cropping for 2 successive years. One spray of ethephon in an “on” year would be effective in reversing and leveling cropping of ‘Imperial’ mandarin for at least 4 years under Mildura conditions.  相似文献   

5.
The overall objective of this work was to improve fruit quality, break alternate bearing and reduce hand thinning using fewer chemicals in fruit crops. A device was constructed for mechanical thinning, which consisted of three independent horizontal rotors with ropes and freely adjustable angles on a frame, mounted on a front three point hitch and powered by the tractor hydraulics. This can be adapted to any fruit tree trained as spindle, Solaxe, (tall) vertical axis or fruit wall (le mur fruitier) irrespective of rootstock employed. Rotor speed varied from 300 to 460?rpm at either 5 or 7.5?km/h tractor speed. Eight-year-old or twelve-old apple trees cvs. ‘Gala’ and ‘Golden Delicious’ were mechanically thinned in 2007 between pink bud and full bloom (flower bud stages 6–8 or F1–F2) near Bonn, Germany; non-thinned and hand-thinned apple trees of the same block and variety served as control. Mechanically thinned flowering branches showed a similar amount of ethylene efflux (0.4–0.6?ppm C2H4/branch) as non-thinned flower branches, preventing potentially unexpected subsequent fruit drop, except for those removed by the rotors. The impact of the horizontal rotors on the branches was from the upper side and removed excessive flowers right to the tree trunk viz. the centre of the tree canopy, where fruits of lesser quality are expected leaving 2–3 flowers per cluster. Leaf damage was less than??10%, even at the fast rotor speed of 420?rpm, which was associated with negligible wood injury. Mechanical thinning induced firmer and sweeter fruit, i.e. tastier apples with longer shelf life, relative to control fruit from non-thinned apple trees. The greatest efficacy in terms of final fruit quality in the grading/sorting was achieved by a rotor speed of 360?rpm at a tractor speed of 5?km/h: Fruit mass increased by up to 20?g and the proportion of fruit larger than 70–75?mm by 10–30% compared with the fruit from non-thinned trees. Mechanical thinning with this newly constructed device led to a 10–20% reduction in yield, but increased returns due to better fruit size and colouration in apple with the potential to overcome alternate bearing.  相似文献   

6.
同源四倍体皇家嘎拉苹果的生长结果特性   总被引：2，自引：1，他引：2  
皇家嘎拉苹果四倍体是一个由皇家嘎拉苹果二倍体经诱变处理获得的品系。为了解皇家嘎拉苹果四倍体与二倍体对照植株在生长结果特性方面的差异,取2种果树的接穗高接到10年生大树上,在植株结果后进行了调查研究。结果表明,由皇家嘎拉苹果二倍体诱变成的同源四倍体植株在高接后第3年开始结果,其花萼、花瓣、雌蕊、雄蕊及花药比对照大;叶片变宽,叶柄和果柄变短粗;单果大,种子数少,果形指数小,果实可溶性固形物、总糖和可滴定酸含量增高;其节间长、叶长及果肉硬度与二倍体则无显著差异。  相似文献   

7.
Summary

Orchards displaying calcium (Ca) deficiency are a common phenomenon worldwide, despite the presence of sufficient Ca in the soil and the plant. A 3-year trial was conducted between the 2007 – 2008 and 2009 – 2010 growing seasons to evaluate the contributions of soil and foliar Ca applications to Ca concentrations in ‘Braeburn’ apple (Malus × domestica Borkh.) fruit. Ca(NO3)2 (Calflo; Yara Africa, Fourways North, South Africa) was applied as six separate foliar sprays until run-off. Applications were made at 1-week intervals between approx. 21 – 70 d after full bloom (DAFB) at 6.75 ml l–1. Soil applications of Ca (TropicoteTM; International ASA, Oslo, Norway) at 300 kg ha–1 were applied at fruit set, or after harvest, according to standard practice. Mineral analysis was conducted to assess the soluble Ca concentrations of whole fruit (without pips and stalks), to quantify the contribution of foliar sprays or soil-applied Ca. Fruit Ca concentrations were maintained at satisfactory levels (4.5 mg Ca 100 g–1 FW) at harvest by applying a series of six foliar sprays early in the season (for all seasons) during the trial period. Fruit Ca concentrations at 80 DAFB were highest in the treatments with foliar applications of Ca. In 2009 – 2010, Ca concentrations in apple fruit were lowest (8.38 mg 100 g–1 FW) for soil application of Ca at fruit set. Ca applications to soil after harvest in the previous season, and soil applications shortly after fruit set in the current season, did not significantly increase Ca concentrations in current-season fruit, providing soil Ca levels were above the minimum requirement for apple trees. A possible explanation is that apple trees regulate their uptake of Ca through the roots when soil Ca is available in sufficient quantities. This confirms the importance of active root growth for efficient Ca uptake by apple trees when applying Ca to the soil.  相似文献   

8.
《Scientia Horticulturae》2004,101(3):243-253
Experiments to test the effectiveness of prohexadione–Ca as a growth inhibitor in apple trees have been carried out for 3 years in the Middle Ebro Valley (Spain). Also, effects on fruit quality and flower initiation were evaluated. The application of 100–400 mg l−1 of prohexadione–Ca between 12 and 30 days after full bloom (DAFB) to ‘Smoothee Golden Delicious’/M9 apple trees resulted in the inhibition of shoot growth, the effect increasing with concentration, and a greater inhibition was obtained when the trees were first sprayed 12–20 DAFB. A second spray was usually needed to avoid a regrowth of the shoots. The effectiveness of the second application was related to the concentration applied and the date of the first spray. The relative increase in trunk-cross-sectional area was not affected by the growth inhibitor. No negative effects on yield and fruit quality were found except for a reduction of soluble solid content. Flower initiation in the following year was not affected. Concentrations of 100–200 mg l−1 applied shortly after full bloom should be recommended, bearing in mind that a second application might be necessary 6–8 weeks later.  相似文献   

9.
The nutrient uptake of fruit trees in the first and second year of cultivation was analyzed. The following fruit species and fruit varieties were examined: sour cherry (‘Schattenmorelle, Rheinland’, Hüttners Hochzucht 170?×?53, one year old tree), pear (‘Conference’, Quince A, two year old tree), apple on M 9 inoculated with the varieties ‘Pinova’ (two year old tree with one year old crown, two year old tree), ‘Elstar’ (one year old tree, two year old tree with one year old crown, two year old tree), ‘Jonagold’ (one year old tree, two year old tree with one year old crown, two year old tree) und Süßkirsche (‘Regina’, Gisela 5, two year old tree).
  1. There was low nutrient uptake in the first and second year of cultivation.
  2. In the second year of cultivation the nutrient uptake of all fruit species was clearly higher than in the first year of cultivation.
  3. In average of the proved fruit varieties the nutrient uptake in the first year of cultivation was: 8?kg N/ha, 2?kg P/ha, 6?kg K/ha, 1?kg Mg/ha and 9?kg Ca/ha.
  4. In average of the proved fruit varieties the nutrient uptake in the second year of cultivation was: 3?kg P/ha, 9?kg K/ha, 3?kg Mg/ha and 26?kg Ca/ha.
  5. Especially in the first year of cultivation the trees of the stone fruits showed a higher nutrient uptake per tree than the trees of the pome fruits. But related to the nutrient uptake per hectar this difference reversed or became infinitely small.
  6. The nutrient uptake of both the three apple varieties and the different plant materials showed only low differences.
  相似文献   

10.
Summary

Fruit mineral concentrations measured at harvest can have major effects on apple fruit quality on the tree or during storage. Orchard practices must therefore seek to optimize fruit mineral composition. The purpose of this study was to describe and elucidate the effects of hand thinning on whole trees and individual spurs on apple fruit mineral composition. Two methods of flower and fruitlet thinning were compared with no thinning on `Braeburn' and `Fiesta' apple trees. Alternate whole flower/fruitlet clusters or all but one flower/fruitlet within every cluster were removed at full bloom or 14±21 d after full bloom. Alternate-cluster thinning reduced final fruit numbers per tree and fruit Ca concentrations by up to 22%, while increasing final fruit size by up to 21%, compared with no thinning. These effects on fruit Ca concentrations were also measured across a range of fruit size classes. Within-cluster thinning at full bloom or up to 21 d after full bloom also reduced fruit numbers per tree but increased fruit size substantially, by up to 65% compared with no thinning, this effect being less for later thinning. However, fruit mineral concentrations were not influenced by this treatment. Some fruiting spurs were singled to one fruit 14 d after full bloom on alternately flower cluster thinned trees and on trees that had not been thinned at bloom, and compared with unthinned spurs on the same trees. Fruit Ca concentrations, primary spur leaf areas and primary spur leaf areas per fruit were greater for spurs bearing a single fruit (achieved by thinning manually or through natural abscission) than for multi-fruited spurs on the same trees. Spurs bearing one fruit on unthinned trees had greater fruit Ca concentrations, primary spur leaf areas and primary spur leaf areas per fruit, but lower fruit weight than the same spurs on alternate-cluster thinned trees. However, spurs on unthinned and alternate-cluster thinned trees with the same primary leaf areas per fruit had similar final Ca concentrations. Fruit size and crop loads were found not to be important in explaining fruit Ca concentration differences between thinning methods. However our results suggest that thinning method may affect Ca accumulation in apple fruit by altering the relationship between fruit numbers and leaf areas on individual spurs.  相似文献   

11.
In a pot experiment with apple trees, cultivar ‘Cox's Orange’, Ca was omitted in the nutrient solution for periods of different length. Trees lacking Ca in the latest 23 of the growth period contained 42 mg kg?1 Ca in the fruits, which is 21% below control. In the bulked sample, average size of fruits was not considerably affected, but the distribution of small and large fruits changed toward more smaller fruits. Concommitantly, bitter pit was reduced compared to the control.Sufficient K supply (1.20–1.70% K in leaf dry matter) given to trees receiving high Ca supply depressed Ca concentration in the fruits to 41 mg kg?1, which is 23% below control. Average fruit size was not significantly changed, but the distribution was towards larger fruits. Under these circumstances bitter pit was increased. Ca deficiency, caused either by omission of Ca or competition between K and Ca, increased fruit rot, russeting and cracks on the fruits. Short term variations in Ca levels were not seen to produce any measurable response.  相似文献   

12.
Summary

1-Aminocyclopropane carboxylic acid (ACC) was applied to apple (Malus × domestica Borkh.) trees or to individual fruiting spurs between full bloom (FB) and 31 d after full bloom (DAFB; mean fruit diameter of 20 mm) to determine the effects of ACC on the ethylene released from detached spurs and on fruit abscission. The rate of ethylene release from detached fruiting spurs increased 1 d after applying 50 mg l–1 ACC at full bloom or 16 DAFB (mean fruit diameter of 10 mm), but ACC had a reduced effect on the rate of ethylene release when it was applied 31 DAFB (mean fruit diameter of 20 mm). ACC reduced fruit set in ‘GoldRush’ apple in a concentration-dependent manner in 2009 and in 2010, but had no thinning activity on ‘Pink Lady’ in 2010. ACC at 200 mg l–1 resulted in the yellowing and abscission of ‘GoldRush’ spur leaves in 2009, but not in 2010. The effects of combining ACC and 5 mg l–1 naphthaleneacetic acid on fruit set in ‘GoldRush’ apple were additive. The application of 200 mg l–1 ACC when fruit are ca. 10 mm in diameter may therefore be a useful chemical thinning treatment for apple fruit.  相似文献   

13.
The aim of this research was to improve inner and external fruit quality and fruit colouration using four-year-old apple ‘Braeburn, Hillwell’ trees on M9 (3?m × 1?m spacing) by employing reflective ground covers and biostimulants at Klein-Altendorf, nr. Bonn, Germany (50°N). Two reflective ground covers were spread on both sides of tree rows seven weeks before anticipated harvest and two biostimulants were applied two times – four and two weeks before harvest. Adjacent trees of the same row without reflective ground cover or without biostimulants served as control.Reflective ground covers significantly improved red colouration from 71°hue in the control to 49°hue with the ground cover Lumilys® and to 40°hue with Extenday®. The red colouration of the lower surface of fruits improved from 85°hue in the control to 52°hue with Lumilys® and 40°hue by Extenday®. Apple trees with Extenday® and Lumilys® produced 69% and 44% well-coloured fruit (with 75–100% fruit colouration) compared with 16–26% in the control.By contrast, an acceleration of ripening processes was not observed in plots with reflective ground covers compared with the control. There were no differences in sugar contents (°Brix) and fruit firmness (kg/cm2), but starch breakdown in fruit with reflective mulch was significantly delayed compared with the control resulting in retarded maturation.An economic analysis based on material costs and lifespan – excluding the labour costs for spreading and removing the ground covers – showed an economic advantage, if these mulches are used more than once a year.Both biostimulants showed neither effects on inner and external fruit quality nor on fruit colouration. Fruits with Wuxal®ATRiun or Sunred® did not improve the percentage of well-coloured fruits (75%–100% fruit surface with red colouration) compared with the untreated control. Similarly, inner and external fruit quality showed no significant differences in fruit firmness, sugar content and starch degradation. An economic analysis based on chemicals’ costs – excluding the labour costs for applying the biostimulants – resulted in no economic advantage. The chlorophyll – based ‘Index of Absorption Difference’ (IAD; measured non-destructively by the DA-meter) in some cases correlated positively with the Streif (maturation) index based on destructive assessment fruit firmness, sugar content and starch breakdown in an ‘ART system’.  相似文献   

14.
The objective of the present study was to thin apple flowers without use of chemicals, in order to improve fruit quality, reduce labour for hand thinning and overcome alternate bearing. The newly developed device comprises three rotors with adjustable angles and vertically rotating ropes, which remove excess apple flowers. Eleven year-old cv. ‘Braeburn’ apple trees were thinned at flower opening (BBCH growth stage 61) with the new device in Klein-Altendorf near Bonn, Germany. Adjacent untreated, hand-thinned or chemically (benzyladenine-)thinned apple trees of the same rows served as controls. Tree branches remained un-damaged by the vertically rotating ropes. Slight leaf damages of less than 8% were observed at the fastest rotor speed of 320?rpm, which also gave the best thinning results. The portion of class one fruits >?70?mm was increased by 10% without yield loss and by up to 20% with yield losses of ca. 5–10%, depending on the settings, relative to the untreated control. This was equivalent to fruit mass gains of 10?g without yield loss and of 20?g with 10%–20% yield loss with economic gain in both cases. The single or double-sided mechanical thinning required 1.2?h ha?1 or 2.4?h ha?1 at a tractor speed of 2.5?km h?1 and reduced the subsequent hand thinning by respectively 20% or 45% (by 7?h or by 15?h/ha or its cost by 50–135 €/ha). The new device gently removed up to one third of both peripheral and central flowers at a cost of less than 100 €/ha and with a negligible risk of over-thinning and without effect on return bloom.  相似文献   

15.
SUMMARY

Eight days after petal fall in 1991, mature 'Delicious'/MM. 106 apple trees and four days after petal fall in 1992, mature 'McintoshVMM. 106 were ringed, scored, root pruned (1 m from the trunk, two sides, 30 cm deep), or treated with ethephon (500 mg 11). Only ringing and scoring reduced vegetative growth. Ethephon advanced fruit maturation and fruit abscission, but root pruning did not affect the trees or fruit significantly. Mature 'Cort-land'/M.7a apple trees were root pruned 8 d after petal fall in 1991 and/or at full bloom in 1992. Root pruning reduced shoot growth, even in the year after treatment. Fruit abscission was reduced in 1991 and 1992 by root pruning in 1991, but root pruning in 1992 had no impact on abscission, in 1992. In an additional experiment, mature 'Mcintosh'/ MM.106 were root pruned 4 d after petal fall in 1991 or root pruned both in 1991 and at full bloom in 1992. Growth and preharvest fruit abscission were reduced in both the year of root pruning and the year after.  相似文献   

16.
Summary

Effects of root damage during the transplant process on growth and nitrogen (N) uptake were studied with one-year-old bench-grafted Malus domestica Borkh ‘Fuji’ on M.26 rootstock apple nursery plants. Plants were potted after grafting and grown outside for one season. At the end of the season uniform trees were selected and randomly divided into four groups. One group of plants were moved into a 2°C cold room with soil and container intact (IR Treatment). Plants in other groups were removed from pots and stored as bareroot in the same cold room for three months. In the spring, bareroot plants were either: (1) transplanted with about 10% of the root system damaged during transplant (TP Treatment and Control-CK); or (2) root pruned by 25% (by volume) prior to transplant (RP treatment). Five trees from each treatment received 1 g of 15NH415NO3 at 12, 41 and 76 d after repotting. Control (CK) trees received no N. Trees were harvested 10 d after each N application, and plant growth and total N and 15N content of different tissues were determined. Root pruning reduced plant total biomass and root biomass at the first two harvests, but the plants from the RP treatment had highest total plant biomass and root biomass at the third harvest. There was no significant difference in the new stem and leaf growth among IR, RP and CK treatments at harvests but the TP treatment reduced new shoot biomass. Plants with intact roots (IR) had the higher total N content while control plants (CK) had the lowest. Root pruning reduced 15N uptake rate at the first two harvests but promoted it at the third harvest. Our results suggest that plant growth and nutrient uptake was suppressed by root pruning/damage during transplanting only in the early season, and the negative effects on growth and N uptake were offset later in the season by compensative root regeneration.  相似文献   

17.
One of the most important factors limiting agricultural expansion and production is the restricted supply of good quality water. The present study examines the effects of K+ and Ca2+ fertilization on sweet pepper production, blossom-end rot (BER) incidence and fruit quality of pepper plants (Capsicum annuum L.) grown under moderate saline conditions. Pepper plants were grown in a controlled-environment greenhouse under hydroponic conditions with different nutrient solutions obtained by modifying the Hoagland solution. The experiment consisted on four K+ treatments (0.2, 2, 7 and 14 mM) +30 mM NaCl, and four Ca2+ treatments (0.2, 2, 4 and 8 mM) +30 mM NaCl, having in common a control without salt with 7 mM K+/4 mM Ca2+. Salinity decreased total fruit yield and marketable fruit yield by 23% and 37%, respectively. The marketable fruit yield reduction by salt treatment was mainly due to the increase in the number of fruit affected by BER. This typical physiopathy of the pepper fruits occurred between 18 and 25 days after anthesis (DAA), when the highest fruit growth rate was reached. Fruit quality parameters were also affected by salt treatment where the fruit pulp thickness and firmness were decreased, and fructose, glucose and myo-inositol fruit concentrations increased with salinity relative to fruits from control treatment. Under saline conditions an increased supply of K+ reduced the fruit fresh weight, the percentage of BER and the marketable yield although promoted the vegetative growth. However, increasing Ca2+ concentration in the nutrient solution increased the fruit production, and the marketable yield as consequence of decreasing the percentage of fruit affected with BER. Fruit quality parameters also were affected by the K+ and Ca2+ treatments.  相似文献   

18.
Studies documenting pistachio fruiting patterns (Pistacia vera L.) conclude this species shows evidence of alternate bearing; fruit production fluctuates between an ‘on’ year of high yields and an ‘off’ year of low yields. However, alternate bearing in pistachio has never been statistically tested. We collected yields of 4288 trees over six years to test for alternate bearing in a mature orchard planted with ‘Kerman’ scions grafted onto P. integerrima rootstock – the combination planted on the bulk of the acreage in California. A majority (58%) of the trees exhibited statistically significant alternate bearing patterns. Yet 42% showed yield patterns that were indistinguishable from random fluctuations, the standard measure of alternate bearing (I) was only modest (mean I = 0.48), and I varied considerably among trees (range = 0.04–0.83). These findings support that pistachio shows alternate bearing behavior but suggest alternate bearing is less ubiquitous and fruiting patterns are more complex than previously suspected. The presence of such a diversity of yield dynamics creates considerable challenges for crop management and research.  相似文献   

19.
Summary

The efficacy of candidate activators of systemic acquired resistance (SAR), Bion® (Syngenta, Basel, Switzerland), Rezist® (Stoller Enterprises, Houston, Texas, USA), and Milsana® (P. J. Margo Pvt. Ltd., Bangalore, India), was evaluated for the control of powdery mildew (Podosphaera xanthii) on cucumber and zucchini. Each candidate activator significantly reduced the incidence of disease on both crops in a glasshouse, where spore inoculum was applied to treated leaves. Both Bion® and Rezist® induced increased chitinase activity in plants, confirming their action as activators of SAR. However, Milsana® did not have this effect, suggesting that its mode of action was as a direct inhibitor of infection by spores. In the field, two or three applications of Bion®, at 14-day intervals, gave consistently better results in protecting cucumber plants from powdery mildew. Several applications of Milsana® alone were less effective than a single application of Bion® alone. However, several applications of Bion® adversely affected plant growth, resulting in lower yields. The application of Milsana® before or after Bion® provided effective control of powdery mildew and minimised the adverse effects of Bion® on yield. Application of all three candidate activators alone, on field-grown zucchini did not control powdery mildew, although a systemic increase in chitinase activity occurred in response to Bion® or Rezist®. A greater understanding of the mode of action of Milsana®, and of the interaction between disease load and the timing of activator application(s) may improve the control of powdery mildew.  相似文献   

20.
Monophosphates reportedly enhance red colouration of bi-coloured apple fruit by stimulating anthocyanin synthesis and, in addition with calcium or potassium, may improve fruit firmness; colour and firmness which may be restricted by the climate in Western Europe. 12-year-old cv. ‘Elstar’ apple trees at Klein-Altendorf near Bonn, Germany, were sprayed weekly with either of two monophosphates four weeks prior to harvest to improve fruit quality, i.e. colouration, sugar and firmness. White, woven reflective cloth was spread as an alternative on the grass strips between the tree rows six weeks prior to harvest for the same purpose. Untreated apple trees served as control. Neither of the three treatments affected fruit maturation, measured as Streif index. The monophosphate formulation containing calcium (Seniphos; 24% P2O5; 4% CaO; 2?×?10?L/ha) increased the sugar content of the cv. ‘Elstar’ apples in the outer as well as in the inner tree canopy and the reflective cloth additionally in fruit of the lower canopy close to the cloth's position on the ground. This white reflective cloth (Extenday) also affected fruit from the outer tree canopy with the largest sugar content (12.6°Brix) and firmness (7.6?kg/cm2) at harvest. The monophosphate formulation containing potassium (Rizammina 42; 8% P2O5, 21% K2O; 3?×? 2.5?kg/ha) improved the category of greater 25% fruit colouration by only 3%. Both Seniphos and the reflective cloth increased this portion by 17–19%, thereby raising the portion of class-1-fruit by 8%, equivalent to additional earnings of 1,060 €/ha. The green ground colour of apples in the shaded inner canopy was retained by either monophosphate. In the well-illuminated tree periphery, however, the ground colour of fruit treated with either monophosphate was less green (more yellow-green) and the top colour was more red. The white reflective cloth induced the same positive effects on fruit colouration to a much larger extent. Both monophosphates increased fruit firmness after 4?months cold storage around 5% at a time when fruit were too soft for marketing as fresh products.  相似文献   

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