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1.
Water logging and salinity of the soil alter both the physical and biological environment of plant roots. In two experiments, we investigated the effects of imposed aeration on yield and the physiological response of tomato (Lycopersicon esculentum L.) variety Improved Apollo growing under protected conditions over a range of salinities (the salinity experiment), and under constant field capacity (FC) or drier soil conditions (the moisture experiment). Subsurface irrigation with aerated water (12% air in water) stimulated above-ground growth, and enhanced the reproductive performance through earliness for flowering and fruiting compared with the control. Fruit yield of tomato with aeration in the moisture experiment was increased by 21% compared with the control (4.2 kg versus 3.7 kg per plant), and the effect of aeration on fruit yield was greater in FC than in the drier treatment. Fruit yield was increased by 38% in saline soil due to aeration compared with the non-aerated control. Increasing salinity from 2 to 8.8 dS m−1, and 10 dS m−1 reduced fruit yield by 18% and 62%, respectively, but 4 dS m−1 did not suppress yield. Aeration in both the experiments increased plant water use and water use efficiency (WUE), expressed as weight per unit of applied water. Biomass WUE was greater by 16% and 32% in the moisture and salinity experiments, respectively. The increased yield with aeration was also accompanied by an increased harvest index (HI) defined as the proportion of dry fruit biomass to total dry biomass, greater mean fruit weight, high fruit DM, and increase in leaf chlorophyll content and shoot: root ratio, and a reduced water stress index (computed from the difference between air and leaf temperature). The benefit gained from aerating irrigation water was not only observed under conditions where air-filled porosity may be low (e.g., in poorly structure sodic soils, or at field capacity in clay soils), but also in drier soils.  相似文献   

2.
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.  相似文献   

3.
Summary

Single-truss tomato plants grown hydroponically (wet-sheet culture) were exposed to a salinity (EC) of 5.0 dS m21 or 8.0 dS m21 at two fruit ripening stages, the immature green stage and the decolouring stage. These salinities were achieved by adding NaCl to the standard solution, which had an EC of 2.4 dS m21. Increased salinity at the immature green stage improved fruit quality more than increased salinity at the decolouring stage but decreased fruit yield more. The reduction in fruit yield was due to a decrease in fruit weight but not in fruit number. Salinity increased the concentration of soluble solids, citrate, ascorbic acid, K, chlorophyll a, chlorophyll b, lycopene, and carotene in the fruit, but the absolute amount of these constituents per fruit was decreased or not affected. These results suggest that the improvement in fruit quality induced by the salinity is caused by the reduction of water import into the fruit. The effectiveness of both salinities was significantly bigger when it was applied at the earlier development stage, suggesting that mature fruit would be less sensitive to strength of the EC.  相似文献   

4.
Summary

The effects of exposing eggplants grown in recirculating nutrient solution to salt stress (6.1 dS m–1) from planting until the beginning of harvesting, on plant growth, yield and macronutrient status was investigated. The salinity was imposed by adding to a basic nutrient solution either additional nutrients at two cation ratios or NaCl. The results showed that the exposure of plants to salinity prior to the beginning of harvesting reduced both vegetative growth during that time and early fruit yield, but the depression of the latter was more severe. The restriction of the early yield was a result of a reduced mean fruit weight due to a lower fruit water content. The detrimental effects of salinity on the mean fruit weight disappeared 25 d after discontinuing the salinity treatments. As a result, the total yield obtained after five months of harvesting was not influenced by exposing the plants to salinity prior to the beginning of harvesting. The salinity source had no specific effect on plant growth. Moreover, the increase of salinity up to 6.1 dS m–1 did not cause any specific nutritional imbalance or toxicity to the plants, irrespective of the salts used to achieve it. It is suggested that the electrical conductivity of the nutrient solution may be raised to 6.1 dS m–1 to control excessive vegetative growth in eggplants grown hydroponically. However, salt treatment should be terminated either at the first harvest, if the total yield is more important than the early yield, or three weeks earlier, if the opposite is true.  相似文献   

5.
Summary

A crop-scale experiment between March and October 2000 investigated the effects of split-root salinity stress and rooting volume on the expansion of leaves, fruit yield and quality in two standard round fruited cultivars of tomato (Lycopersicon esculentumMill) Solairo and Espero, grown in rockwool. To implement the treatments, a split-root method was utilized whereby different levels of salinity (expressed as EC), adjusted by the addition of NaCl, was administered to two halves of a root system. The split-root high EC (2.8/8.0 dS m–1) treatment enhanced fruit quality by increasing the concentrations of sugar, acid, total soluble solids and reducing the incidence of visual defects such as uneven ripening and gold-spot. Split-root high EC did however reduce leaf area that corresponded with low K concentration in the leaf tissue. The split-root method utilized doubled the rooting volume compared with the standard single rockwool slab, but this extra rooting capacity had no detectable effect on leaf expansion, yield or fruit quality. Although there was little impact on yield for ten weeks after the imposition of the high EC split-root treatment, mean reductions in weekly yield occurred thereafter and were of the order of 9 and 13% for ‘Solairo’ and ‘Espero’ respectively through to the end of the experiment. The fall in yield was due, in part, to a decrease in fruit size. Whilst water uptake was reduced it was unclear how the effects on leaf growth and fruit yield were mediated in the shoot. Possible processes that coordinate responses to root-zone salinity stress are discussed. The potential use of the split-root system in commercial production is considered.  相似文献   

6.
We investigated the hypothesis that manipulating water out-flow of a plant through the shoot environment (potential transpiration, ET0) in a glasshouse could modulate the effect of salinity/osmotic potential in the root environment upon yield of tomatoes. Contrasting root-zone salinity treatments were combined with two climate treatments — a reference (high transpiration, HET0) and a “depressed” transpiration (low transpiration, LET0). The salinity treatments, characterised by their electrical conductivity (EC) were 6.5, 8 and 9.5 dS m−1, were always coupled with a reference treatment of EC=2 dS m−1. In another experiment, concentrated nutrients (Nutrients) and nutrients with sodium chloride (NaCl) at the same EC of 9 dS m−1 were compared.Marketable fresh-yield production efficiency decreased by 5.1% for each dS m−1 in excess of 2 dS m−1. The number of harvested fruits was not affected; yield loss resulted from reduced fruit weight (3.8% per dS m−1) and an increased fraction of unmarketable harvest. At the LET0 treatments, yield loss was only 3.4% per dS m−1 in accordance with the reduction in fruit weight. Low transpiration did increase fruit fresh yield by 8% in both NaCl and Nutrients treatments at an EC=9 dS m−1. Neither EC nor ET0 affected individual fruit dry weight. Accordingly, fruit dry matter content was significantly higher at high EC than in the reference (4% per each EC unit in excess of 2 dS m−1) and responded to ET0 to a minor extent. Control of the shoot environment in a greenhouse to manipulate the fresh weight of the product may mitigate the effects of poor quality irrigation water without affecting product quality.  相似文献   

7.
Summary

The commercial F1 tomato hybrid (Lycopersicon esculentum L. Mill) cv. Radja (GC-793) was cultivated with low (control), moderate (70 mM NaCl) and high (140 raM) salinities under greenhouse conditions for 14 weeks. The effects of different salinity levels on fruit weight and major chemical components determining fruit quality were assessed. Red ripe fruits were harvested to determine fruit weight, size and composition. The water content and mineral composition were determined in whole fruits; the carbohydrate, organic acid and soluble protein contents were analyzed in pericarp tissue. Moderate salinity reduced the fresh and dry fruit weights by only 10 and 13%, respectively, while high salinity reduced them by 40 and 33% compared with control fruits. The water content was not significantly affected by salinity. Thus, fruit weight does not seem to be limited by the water supply under these conditions. The amount of Na+ significantly increased only at high salinity, while Ca2+ and Mg2+ contents were not affected. K+ content, which represents more than 70% of the mineral composition, vends to increase with salinity. The citric acid content slightly increased at moderate salinity, while both citric and malic acids contents were reduced at high salinity, increasing the citric/malic ratio. The pH values were always about 4. The low content in soluble proteins was reduced by high salinity, while moderate salinity increased it. In pericarp tissue of moderately treated fruits, the fructose and glucose contents were three times and twice as high as control and highly salinized-ones. Starch, sucrose and myo-inositol also accumulated under salinity. Hexoses and starch accounted for 20, 66 and 42% of the pericarp dry matter in control, moderate and highly salinized fruits, respectively.  相似文献   

8.
A single GA3-spray at petal-fall to the entire tree enhanced initial set in the ‘Navelate’ sweet orange (Citrus sinensis L. Osbeck), but this effect was transient and in most cases final yield was not increased. When followed by girdling, final yield was increased even in the most productive orchards, this effect being due to an increase in fruit number while fruit size was unaffected. The response was markedly dependent on the GA3 concentration, 5 mg l?1 giving the best results. Higher concentrations up to 20 mg l?1 even reduced yield compared to the untreated control trees. Chlormequat reduced the number of fruits finally cropped without affecting their size, an effect which may be explained through a reduction in the endogenous gibberellin levels.  相似文献   

9.
Summary

The effects of four soil NaCl levels (0, 1 600, 3 200, and 4 800 μg g?1) on the growth, chemical composition and plant water relationships of pistachio cvs Badami, Fandoghi and Kale-ghoochi were studied in an arid calcareous soil in a glasshouse experiment. Fandoghi was less tolerant to NaCl salinity probably because of higher uptake and/or transport of CI and Na ions, lesser osmoregulatory ability, and greater reductions in the top and root dry weights with respect to the CI concentration in the soil saturation extract. The 50% reduction in the top and root dry weights were obtained, respectively, at an electrical conductivity of the saturation extract (ECe) of 9.3 and 10.0 mmhos cm?1 for ‘Badami’, 7.9 and 7.9 mmhos cm?1 for ‘Fandoghi’ and 9.6 and 10.0 mmhos cm?1 for ‘Kaleghoochi’. Growth of tops and roots was stopped, respectively, at ECe values of 18.7 and 20.6 mmhos cm?1 for ‘Badami’; 15.9 and 15.5 mmhos cm?1 for ‘Fandoghi’, and 19.2 and 20.4 mmhos cm?1 for ‘Kale-ghoochi’.  相似文献   

10.
Summary

Strawberry plants were grown in rockwool under glasshouse conditions at NaCl salinities of 2.6,5.9 and 8.6 mS cm-1 and at total irradiances of 2.1 and 4.9 MJ m?2d?1. Increasing salinity and irradiance reduced leaf water potential (ψω), osmotic potential (ψπ) and turgor potential (ψτ). There was an interaction between salinity and irradiance on with the lowest ψπ recorded for the unshaded leaves. Increased salinity altered the ionic composition of the leaf. Chloride concentration was increased from 0.03 to 0.61 % (D.W.) while NO3 content in the leaf sap was reduced from 10.51 to 3.60 mg ml-1 as salinity increased from 2.6 to 8.6 mS cm?1. Expressed on a fresh-weight basis, the concentration of K was reduced at high irradiance whereas Ca and Mg were enhanced. On a dry-weight basis K, Na, Ca and Mg were unaffected by salinity treatment. Net photosynthesis was reduced by high salinity but only in plants grown in unshaded conditions.  相似文献   

11.
SUMMARY

Greenhouse tomato plants (Lycopersicon esculentum Mill. cv. Capello) were grown in a peal-moss based substrate and supplied with nutrient solutions of high (4.5 mS cm-1) or low (2.3 mS cm-1) electrical conductivity (EC) and under high (95 ± 5%) or low (55 ± 8% of capillary capacity) soil water content, to elucidate how EC and soil water status affect plant photosynthesis and related physiological processes. Two weeks after beginning the treatments, photosynthesis (Pn) was measured during changes of photo-synthetic photon flux (PPF) from 0 to 1200 u.mol m-2 s-1 using a gas exchange method. The rectangular hyperbolic model (Pn = Pmax KI (1-KI)-2 -r) provided a good fit for the photosynthetic light-response curve. High EC treatment changed the curve by increasing the initial slope (quantum yield) and decreasing photosynthetic capacity at high PPF. However, soil water deficit not only decreased the photosynthetic capacity, but also decreased quantum use efficiency. Depression of Pn was attributed to decreased stomatal (gs) and mesophyll (gm) conductances, but gs was depressed more than gm. The ratio of gm/(gm + gs), an indicator of water use efficiency and a measure of relative control of Pn by carboxylation and C02 supply, was higher for high-EC treated plants. Chlorophyll content was increased by high EC treatment, and was consistent with quantum yield. Leaf water potential was decreased by high EC and/or low soil water content and the decreases in leaf water potential ultimately accounted for the Pn depressions. The effects of high EC and soil water deficit were additive on photosynthesis and most related physiological processes.  相似文献   

12.
 调查了陕西渭北地区915 个盛产期红富士苹果园的土壤有效养分、全年施肥和产量情况, 并在合阳县1 个果园通过8 年定位试验研究了长期施用氮、磷、钾肥对苹果产量、单果质量的影响及肥 料农学效率和肥料贡献率的变化。结果表明,土壤碱解氮、速效磷、速效钾含量的平均值分别为60.1 mg · kg-1、17.7 mg · kg-1 和173.0 mg · kg-1,有机质含量为12.6 g · kg-1,最高分布频率的土壤养分分布范围 分别为碱解氮40 ~ 60 mg · kg-1,速效磷10 ~ 20 mg · kg-1,速效钾150 ~ 200 mg · kg-1,有机质10 ~ 15 g · kg-1。 碱解氮和速效磷含量与苹果产量的相关性分别达到极显著和显著水平,土壤速效钾和有机质含量与产量 的相关性不显著。果园氮、磷、钾肥平均用量分别为纯N 454.5 kg · hm-2、P2O5 327.7 kg · hm-2、K2O 313.2 kg · hm-2,有机肥平均用量4.7 t · hm-2;纯N、P2O5 和K2O 用量均为200 ~ 400 kg · hm-2 的分布频率最高, 仅26.6%的果园施用有机肥。氮、磷、钾肥用量与苹果产量和土壤速效氮、磷、钾含量具有极显著或显著 相关性。在高产年份、中产年份和低产年份,氮肥对苹果产量、单果质量的影响效果及其农学效率和肥 料贡献率均大于磷和钾肥。对苹果产量的影响,高产年份磷肥显著大于钾肥,中、低产年则无显著差异。 对单果质量的影响效果,高产和中产年份磷肥和钾肥无显著差异,低产年份钾肥显著大于磷肥。氮、磷、 钾肥的农学效率和肥料贡献率,在高、中产年份为氮 > 磷 > 钾,低产年份为氮 > 钾 > 磷。  相似文献   

13.
In drip irrigation experiments where water was applied daily it was found that low water tensions could be maintained in the soil to a range of 10 to 20 centibars and that these conditions had a considerable influence on yield and quality of processing tomatoes, Lycopersicon esculentum cv VF 317. The response of the plant in different growth stages to low soil water tensions was studied. Irrigation during the period of fruit set and fruit development was found to increase yield levels by 53 t ha-1 compared with non-irrigated plants. Irrigation applied only during the period of fruit development had a favourable influence on yield as well as on the efficiency of water utilization. However, irrigation at this stage had an unfavourable influence on fruit quality characteristics, namely, total soluble solids, acidity, viscosity and vitamin C. The effects of irrigation on fruit set and fruit development are discussed.  相似文献   

14.
设施果类蔬菜土壤EC 值动态及盐害敏感性分析   总被引：1，自引：0，他引：1  
在建立饱和及土水比1∶5（m∶v）条件下ECe 与EC1:5 相关关系的基础上,建立EC1:5 的土壤盐分分级指标,评价了传统管理条件下设施越冬长茬和春茬的土壤盐分动态。结果表明：设施菜田土壤ECe 与EC1:5 呈极显著正相关,在京郊土壤条件下换算公式为EC1:5 =0.105 ECe;果类蔬菜中茄子和辣椒属敏感蔬菜作物,苗期和全生育期耐盐性根层土壤EC1∶5 临界值分别为0.10 dS·m -1 和0.30 dS·m -1,当季根层土壤EC1∶5 可接受调控范围为0.30～0.50 dS·m -1;番茄和黄瓜属非敏感蔬菜作物,苗期和全生育期耐盐性根层土壤EC1:5 临界值分别为0.30 dS·m -1 和0.60 dS·m -1,当季根层土壤EC1∶5 可接受调控范围为0.60～0.90 dS·m -1;日光温室越冬长茬土壤EC1:5 均值从定植至翌年3 月一直稳定在0.30～0.34 dS·m -1 之间,之后逐渐下降,7 月降至0.15 dS·m -1;塑料大棚春茬定植后根层土壤EC1:5 逐渐下降,4 月之前为0.29～0.30 dS·m -1,7 月降至0.20 dS·m -1;结合蔬菜作物耐盐指标发现,传统管理条件下日光温室越冬长茬和塑料大棚春茬蔬菜作物在苗期易出现盐害问题;越冬长茬敏感蔬菜作物从定植至翌年3 月期间,土壤盐度易超过其耐盐临界值,需要合理水肥调控以防盐害。  相似文献   

15.
Zinc (Zn) deficiency is frequently observed in mangoes grown in calcareous soils. Inherent inability of mango to extract sufficient Zn from the soil exacerbates this situation. Therefore, mitigating effects of Zn application was investigated on flowering, fruit setting, yield and quality of mango cv. Samar Bahisht Chaunsa growing in calcareous soils. The experiment consisted of five treatments: control—no Zn, soil application of 50 and 100 g ZnSO4 per tree and foliar application of 0.5? and 1.0?% ZnSO4 solution. Zn was applied twice in the 2nd week of November, 2011 and 3rd week of March, 2012, respectively. The experiment was repeated on the same dates during the next growing season. Zn application significantly increased number of flower panicle, fruits matured panicle, leaf Zn concentrations, fruit size, peel thickness, fruit weights at harvest and after ripening and fruit yield tree, whereas it reduced malformed panicles and early fruit drop. However, flower sex ratio and fruit set remained statistically unaffected. Similarly, fruit quality in terms of total soluble solids, flesh color, aroma, flavor and overall acceptability significantly improved as compared to control. Foliar application mitigated Zn deficiency more effectively than the soil application in calcareous soils.  相似文献   

16.
Protected horticultural crops as well as those planted in open fields particularly in the Mediterranean region have to cope with increasing salinization of irrigation water. High salinity of the supply water has detrimental effects on soil fertility and plant nutrition and reduces crop growth and yield. This study was conducted to determine if pre-inoculation of transplants with arbuscular mycorrhizal (AM) fungi alleviates salt effects on growth and yield of tomato (Lycopersicon esculentum Mill. Cv. Marriha) when irrigated with saline water. Tomato seeds were sown in polystyrene trays with 20 cm3 cells and treated with AM fungi (AM) or without (nonAM) Glomus mosseae. Once the seedlings were reached appropriate size, they were transplanted into nonsterile soil in concrete blocks (1.6 m × 3 m × 0.75 m) under greenhouse conditions. The soil electrical conductivity (ECe) was 1.4 dS m−1. Plants were irrigated with nonsaline water (ECw = 0.5 dS m−1) or saline water (ECw = 2.4 dS m−1) until harvest. These treatments resulted with soil EC at harvest 1.7 and 4.4 dS m−1 for nonsaline and saline water treatments, respectively. Root colonization with AM fungi at flowering was lower under saline than nonsaline conditions. Pre-inoculated tomato plants with AM fungi irrigated with both saline and nonsaline water had greater shoot and root dry matter (DM) yield and fruit fresh yield than nonAM plants. The enhancement in fruit fresh yield due to AM fungi inoculation was 29% under nonsaline and 60% under saline water conditions. Shoot contents of P, K, Zn, Cu, and Fe were higher in AM compared with nonAM plants grown under nonsaline and saline water conditions. Shoot Na concentrations were lower in AM than nonAM plants grown under saline water conditions. Results indicate that pre-inoculation of tomato transplants with AM fungi improved yield and can help alleviate deleterious effects of salt stress on crop yield.  相似文献   

17.
To investigate the feasibility of using salt tolerant rootstock to increase fruit yield and quality of cucumber under NaCl stress, a greenhouse experiment was carried out to determine fruit yield, leaf relative water content, fruit quality, and mineral composition of cucumber plants (Cucumis sativus L. cv. Jinchun No. 2), either self-grafted or grafted onto the commercial salt tolerant rootstock Figleaf Gourd (Cucurbita ficifolia Bouche) and Chaofeng Kangshengwang (Lagenaria siceraria Standl). Plants were grown in a substrate culture (peat:vermiculite:perlite = 1:1:1, v/v) and irrigated with half-strength Hoagland solutions containing 0, 30, or 60 mM NaCl. The results showed that salinity significantly reduced fruit yield of cucumber owing to a decrease both in mean fruit weight and fruit number. Rootstock had no significant effect on leaf relative water content. Plants grafted onto Figleaf Gourd and Chaofeng Kangshengwang had higher fruit number, marketable and total fruit yield than those of self-grafted plants under 0, 30, and 60 mM NaCl, which could be attributed to, at least in part, the higher K+ but lower Na+ and/or Cl− contents in the leaves. Salinity improved fruit quality by increasing fruit dry matter, soluble sugar, and titratable acidity contents of all the plants, but had no significant effect on vitamin C content. In comparison to the self-grafted plants, plants grafted onto Figleaf Gourd and Chaofeng Kangshengwang had an overall improved fruit quality under NaCl stress owing to an increase in contents of soluble sugar, titratable acidity, and vitamin C, and a decrease in the percentage of non-marketable fruit and Na+ and/or Cl− contents of fruits in comparison to the self-grafted plants, mainly under 60 mM NaCl. Overall, it is suggested that the use of salt tolerant rootstock could provide a useful tool to improve fruit yield and quality of cucumber under NaCl stress.  相似文献   

18.
Application of 2,4-D and 2,4,5-T at concentrations ranging from 5 to 20 mg l?1 to 5-year-old ‘Pant Lemon-1’ (Citrus limon Burm) trees reduced the vegetative growth in terms of height, spread, shoot length, number and size of the leaves in the autumn flush. Various NAA treatments (5–20 mg l?1), however, enhanced growth, but not to the extent that was observed after GA3 treatments. Application of GA3 at 10–40 mg l?1 significantly enhanced all aspects of growth, and the effects were most pronounced at 20 and 40 mg l?1. Nutritional status of the leaves showed a slight variation in relation to vegetative growth under various treatments.Some 2,4-D- and 2,4,5-T-treatments increased the fruit yield over the control, which could suggest mobilization of foods even at the expense of reduced vegetative growth. On the other hand, NAA, particularly at 10 mg l?1, increased both vegetative growth and yield, suggesting that the transport of the photosynthates from the leaves to the fruits was not at the expense of new growth extension. Due to excessive growth enhancement under higher concentrations of GA3 (20 and 40 mg l?1), comparatively fewer nutrients were translocated to the fruit “sinks”, thereby resulting in a non-significant decrease in yield.  相似文献   

19.
Fertilizer recommendations for citrus production on heavier textured, calcareous soils increase with the age of the tree up to 168 kg N ha−1 year−1 from a soluble source in one or two applications. Such practices may be inefficient and could cause detrimental effects on fruit quality. A variety of fertilization practices are used in South Texas, and additional evaluation is needed. Rates and sources of nitrogen (N), phosphorus (P), and a commercial program consisting of both a soil component containing organic acids and a foliar component were evaluated on grapefruit production for 6 years. Increasing rate of N application increased leaf nutrient concentration, grapefruit yield, and affected fruit shape as indicated by a decrease in the equatorial:polar diameter (E:P) ratio. Since the response to increasing N application by the E:P ratio was linear while grapefruit yield was quadratic, high N application has a negative effect on fruit shape beyond the level of increasing total yield. Phosphorus application had no effect on any parameter measured, even though soil testing indicated soil P levels were below those at which a P response would be expected. Comparisons between granular 21-0-0 applied broadcast and liquid N-32 injected in a band in the soil at the drip line showed an increase in the number of fruit per tree, but no differences in yield. The ‘Actagro’ program greatly improved available soil P levels and increased the juice brix:acidity ratio, but did not affect grapefruit yield. Phosphorus availability may therefore be a factor in improving grapefruit juice quality. The soil profile within the citrus root zone was found to contain large amounts of inorganic N, but availability of this residual N was limited since yield responses occurred at the N application rates applied in this study. The amount of N contained in the fruit harvested was a small fraction, roughly 5–10%, of the residual amount in the soil. While N uptake in the fruit increased with N fertilizer application, the increase in N taken up relative to the amount applied averaged 42%.  相似文献   

20.
Summary

Grapevines, cv. Thompson Seedless were treated with the plant growth regulator paclobutrazol in the spring of 1984. The treatments consisted of four soil application rates (including a zero control) of paclobutrazol on two phenological dates (budbreak and bloom). Vegetative growth, as measured by pruning weight, vine yield and fruit maturity characteristics, were determined in 1984 and in the next three growing seasons. There was no significant difference in vine yield between treatments at harvest in 1984; however, the fruit of vines receiving paclobutrazol at budbreak had accumulated less sugar at that time. Paclobutrazol application significantly (P < 0.01 ) reduced pruning weights in 1984 for all vines receiving paclobutrazol. Only the highest rate of paclobutrazol significantly reduced pruning weights in 1985. The number of clusters per vine and yield were significantly less for the treated vines than for the control ones in 1985 and 1986. Pruning weights in 1986 and yield in 1987 showed no significant differences between treatments. The results indicate that a single soil application of paclobutrazol was effective in reducing vegetative growth of Thompson Seedless grapevines for a period of two years if the rate of application was greater than 1.1 kg a. i. ha-1. However, the adverse effect of this growth regulator on vine yield indicate that it would be of little practical use when applied via the soil to this seedless cultivar.  相似文献   

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