Influence of shoot age on floral development and early fruit set in avocado (Persea americana Mill.) cv. Hass

Floral bud development, early fruit set, bud size, leaf nitrogen and shoot starch content were recorded in spring, summer and autumn shoots of ‘Hass’ avocado (Persea americana Mill.). Floral initiation occurred in late autumn, but only in buds on terminal shoots (the last-formed shoot module on a terminal or axillary growth axis). In branching systems with three growth flushes, more flowers were produced and more fruit set on autumn and summer, than on spring flush terminal shoots. Floral development and leaf nitrogen accumulation occurred later in autumn than in summer shoots, but leaf numbers, dry and fresh weights, starch content of wood, mean floral status at anthesis and anthesis date were similar. The results suggest that nitrogen and starch were present in excess during floral development, and that shoot age did not influence the ability of a shoot to flower and set fruit, provided the shoot had sufficient vigour to produce new shoot growth in spring.     

Effect of harvest date and applied ABA on polyphenol oxidase levels in avocado (Persea americana Mill.) fruit

Summary

‘Fuerte’ avocado fruits from five harvest dates, which spanned the normal packing season, were infused with different amounts of ABA from zero to 550 ng per gram fresh mass of fruit. After ripening at 21°C, the fruits were analysed for PPO activity and residual ABA. Both ABA and harvest date affected PPO activity, with the greater effect being time of harvest. The later the harvest date and the higher the level of infused ABA, the greater was the effect on PPO activity. Early in the season the infused ABA had no effect upon PPO activity. This study has shown that ‘Fuerte’ fruit with the best potential for long distance transport are those harvested soon after minimum legal maturity. If fruits must be hung (tree stored) after maturity, they should be stressed as little as possible.     

Maturity and water loss effects on avocado (Persea americana Mill.) postharvest physiology in cool environments

The influence of cold storage, increasing fruit maturity and water loss on the ripening physiology of ‘Fuerte’ avocado was investigated. Fruit cold stored for 28 d at 5.5°C always subsequently ripened faster than non-stored fruits of a similar maturity. Non-stored fruit showed an expected decrease in ripening time with increasing maturity. In cold stored fruit the relationship between ripening time and maturity was less clear. Cold stored fruit lost less water during ripening than non-stored fruit of similar maturity, but lost water faster than non-stored fruit. Increasing maturity reduced the total amount of water lost during ripening. Cold storage increased the incidence of mesocarp discoloration which became more severe with increasing fruit maturity. Passive water infusion into fruit had no effect on the rate of fruit ripening (and water is obviously not involved as a ‘ripening trigger’) but totally inhibited the manifestation of postharvest browning disorders.     

Evidence for a major role of honeybees (Apis mellifera) rather than wind during avocado (Persea americana Mill.) pollination

Summary

The purpose of this study was to determine the relative importance of honeybee (Apis mellifera) activity and wind in the pollination of avocado (Persea americana Mill.) trees. Data on the pollination rates of five cultivars of avocado, honeybee densities, ambient temperatures, and wind velocities were recorded in an orchard in Israel on 61 d over a period of 7 years. The effect of wind velocity on avocado-flower pollen under laboratory conditions was also studied. Rates of pollination showed highly positive correlations with honeybee density, whereas no correlations were observed with wind velocity. Under laboratory conditions, no effect of wind velocities equivalent to those measured in the field was observed on avocado-flower pollen. Our results agree with earlier work in which wind contributed only slightly to avocado yield. Hence, we conclude that contrasting data which show the effectiveness of wind pollination in avocado are not relevant to most avocado-growing regions, including Israel and California. It is, therefore, strongly recommended that avocado growers continue using honeybees for pollination.     

油梨PaWRI1和PaWRI2基因的克隆、序列分析及表达研究

以‘哈斯’油梨(PerseaamericanaMill.)为试材,通过RACE及RT-PCR技术分别克隆得到2个AP2/EREBP类转录因子WRI1和WRI2基因的c DNA全长,分别命名为PaWRI1(GenBank登录号:MH367865)和PaWRI2(GenBank登录号:MH367866)。其中,PaWRI1基因全长为1 396 bp,含1 155 bp开放阅读框,编码384个氨基酸;PaWRI2基因全长为1 782 bp,含1 287 bp开放阅读框,编码428个氨基酸。PaWRI1和PaWRI2基因属于AP2/EREBP类转录因子家族,其编码氨基酸序列中分别均存在2个和1个典型的AP2/ERF DNA结合位点。实时荧光定量PCR检测结果表明:在油梨果实发育过程中,果肉中PaWRI1基因的相对表达量始终快速上升,PaWRI2基因的相对表达量先少量下降,而后缓慢上升;PaWRI1基因相对表达量变化与油脂积累的变化较一致,PaWRI2基因相对表达量变化与油脂积累的变化不一致。因此,推测在油梨果实发育过程中,果肉中PaWRI1基因可能参与调控油脂积累过程。     

Effects of fruit thinning,pollination and paclobutrazol on fruit set and size of persimmon (Diospyros kaki L.) in subtropical Australia

Summary

A factorial combination of three cultural factors (± hand-pollination, ± growth retardant, ± fruit thinning) were evaluated for their effects on fruit set and fruit size of ‘Fuyu’ persimmon (Diospyros kaki L.) in subtropical Australia (Lat. 27° S). Treatments were applied to individual shoots on mature seven year old trees. Fruit set of pollinated flowers was high compared with non-pollinated flowers (91% vs. 47%). Pollinated fruit also grew faster at all stages of fruit development and, at harvest, fresh weights were 25% heavier. Palcobutrazol significantly (P<0.05) increased fruit weight by 7% compared with controls but did not increase fruit set. Irrespective of treatment, fruit weight was not correlated (r<0.3, n.s.) with shoot length, number of nodes per shoot, fruit nodal position, shoot dry weight, leaf area per shoot, and number of leaves per shoot. Fruit fresh weight was only poorly correlated with shoot base diameter (r = 0.41*). Pollinated fruit had significantly (P<0.05) higher concentrations of nutrients (N, K, Ca, and Zn).     

基于SSR分子标记的油梨种质遗传多样性分析

用23对SSR多态性引物对收集的54份油梨种质材料进行PCR扩增,利用Popgene 1.32计算遗传多样性参数,采用NTSYSpc 2.1计算种质间的遗传相似系数,并进行UPGMA聚类分析和主成分分析.结果表明,23对SSR引物共扩增出多态性位点119个,每对引物扩增的多态位点在2?10个之间,平均为5.17个,多态...     

设施栽培灵武长枣、冬枣休眠特性研究

以宁夏设施栽培灵武长枣、冬枣为试材,采用温度记录仪和水浸枝条萌芽法,应用3种需冷量估算模型(≤7.2℃模型、0~7.2℃模型和犹他模型),对其需冷量进行估算,并测定了相关生理指标。结果表明:不同估算模型下相同枣品种需冷量值略有差异;以≤7.2℃模型估算,设施栽培灵武长枣需冷量值为446h;设施栽培冬枣为470h。适宜的萌芽温度20~25℃,在休眠后期至萌芽初期,枝条可溶性糖含量呈下降趋势,蛋白质含量呈上升趋势。     

The effect of paclobutrazol injected into the soil on vegetative growth and yield of Vitis vinifera L., cv. Thompson Seedless

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.     

Emulsion coatings control fruit fly and anthracnose in mango (Mangifera indica cv. Manila)

Summary

The potential effect of a hydrodispersion of maltodextrin, carboxylmethylcellulose, propylene glycol and sorbitan esters, on the reduction or prevention of spoilage caused by the fungus Colletotrichum gloeosporioides which produces anthracnose and by the fruit fly Anastrepha oblicua, was investigated as a coating for mango (Mangifera indica cv. Manila) fruit from commercial orchards in Jalcomulco, Veracruz, México. Coated and control mangoes were stored at 15 and 25?C and 85±5% r.h. Every 3 d, the coating was removed by washing with water, to determine the time necessary to minimize the damage caused by the anthracnose and the fruit fly larvae. In uncoated mangoes, larval growth and anthracnose manifestation occurred within 6 d at both storage temperatures. In coated mangoes, fruit fly larvae proliferation was avoided and anthracnose incidence was reduced. The results suggested that coatings should be remained for 9 d to avoid fruit fly larvae proliferating and minimize anthracnose incidence by 70%. Applying coatings may be part of a set of superficial treatments to guarantee the phytosanitary certification of tropical fruits such as mangoes.     

Reduction of apple tree height (Malus domestica Borkh) cv. Ultra Red Gala/MM111 does not decrease fruit yield and quality

In Chile, like in other countries, a high percentage of apple (Malus domestica Borkh) orchards are grafted on vigorous or semi-vigorous rootstocks. The need to decrease the amount of labor involved and increase efficiency has motivated this study on the effect of reducing the height of cv. Ultra Red Gala/MM111 trees in a commercial orchard in the Maule Region of Chile. Apple trees were planted in 2003, and their tree heights were adjusted to 2.5, 3.0 and 3.6 m prior to blooming in 2006. The reduction of plant height from 3.6 m to 2.5 m determined a significant reduction in canopy volume (26% and 29% in 2007/2008 and 2008/2009, respectively), but no differences were detected in leaf area index (LAI) and the photosynthetic active radiation (PAR) transmitted through the canopy. However, a higher proportion of the canopies of the shorter trees had over 30% of incident PAR, the threshold for the production of good fruit quality and flower-bud differentiation. There were no differences in fruit production among plant heights, accumulating 131 tonnes ha⁻¹ in the three growing seasons. Over the three seasons, the shortest plants (2.5 m) required 19, 57 and 42% less labor time at harvest, respectively, than the plants maintained at a height of 3.6 m. There were no evident differences in fruit quality among the treatments; flesh firmness varied between 73.0 and 74.0 N, soluble solids between 11.6 and 12.6°Brix, mean weight between 180 and 200 g, and the percentage of red coloring exceeded 59% of the Premium fruit in the three growing seasons. Our results suggest that it is possible to manage plants with reduced height on semi-vigorous rootstocks and thus reduce the time necessary for harvesting, without affecting fruit yield and quality.     

冻结终温和贮藏温度对梨枣果实的影响

以梨枣为试材,研究了冷冻、冻结终温和冻藏温度对果肉细胞相对活力、果肉细胞膜透性和果实品质的影响.试验结果表明:梨枣冷冻后,果肉细胞活力下降了85.0%.冻藏8个月后,贮藏在-35℃中的枣果果肉细胞相对活力比贮藏在-22℃中的高27.4%.同时,果肉细胞相对活力和果肉细胞膜透性之间呈极显著负相关(r=-0.9023).冻结终温和贮藏温度对果肉细胞膜透性有显著的影响.梨枣冷冻后,果肉硬度极显著下降,而在贮藏过程中,没有明显变化.梨枣在冻藏的后4个月,抗坏血酸含量显著下降,下降幅度达37.1%～40.2%;可溶性固形物含量在贮藏前4个月显著下降,后4个月又显著上升;可滴定酸含量没有受到冷冻、冻结终温和贮藏温度的显著影响.     

Chemical composition and antifungal activity of cuticular wax isolated from Asian pear fruit (cv. Pingguoli)

In order to understand the cuticular wax properties of Asian pear fruits (cv. Pingguoli), a series of assays was conducted on extraction, fractionation and determination of composition. The results showed that the maximum yield of wax from the fruit was obtained by chloroform/methanol (3:1), and then by chloroform extraction. Polar and low polar fractions occupied 64.3% and 26.9% of total crude wax by column chromatography. 54 and 22 components were identified in polar and low polar fractions by GC/MS, respectively. Long-chain fatty acids and triterpenoids predominated in polar fraction and n-alkanes were predominant in low polar fraction. In vitro tests indicated that polar fraction, low polar fraction and total crude wax inhibited spore germination and mycelial growth of Alternaria alternata, which is a causal agent of Alternaria rot of pears, and the maximum inhibition was obtained by polar fraction. These findings indicated that n-alkanes in low polar fraction and triterpenoids, fatty acid in polar fraction might have contributed to the antifungal properties of pear fruit cuticular waxes.     

Effects of chemical growth regulators on fruit production of cherries:. II. Effects of fruit-setting hormone and daminozide sprays on colour development,fruit size and fruit composition of cvs Merton Glory and Van cherries

The application of GA₃ alone or in combination with auxins and/or diphenylurea delayed the development of red colour on cherries if applied at the cot-split stage or two weeks after full bloom. Petal-fall applications were less effective and blossom-time applications ineffective in this respect. The hormone mixtures did not induce a significantly different response from GA₃ alone. Application of daminozide enhanced red colour development, totally counteracting the effect of GA₃ applied at petal-fall and partially that of GA₃ applied later .The soluble solids content of the fruits was reduced by the hormones and increased by daminozide. Fruits were smaller where hormone treatment had greatly increased yield but were larger where they only doubled the yield. Daminozide increased fruit size. Hormones affected fruit mineral contents, P, K and B being reduced in the flesh and N, P and K in the stones. Stone mineral levels were much higher than those in the flesh, particularly Ca.     

Rhizobacteria as bioenhancer and biofertilizer for growth and yield of banana (Musa spp. cv. ‘Berangan’)

Banana, an important fruit crop, requires high amounts of fertilizers for commercial cultivation, which is costly and can be hazardous to the environment when used excessively. Inoculations of plant growth promoting rhizobacteria (PGPR) have been shown to produce beneficial effects through growth stimulation in legumes and cereals, and an attempt has been made to use rhizobacteria in bananas. Three experiments were conducted to observe the effects of plant growth promoting rhizobacteria (PGPR) inoculation on root stimulation and colonization, nutrient absorption, growth and yield of bananas (Musa spp. cv. ‘Berangan’, AA type). The results showed that inoculation together with 33% N improved the bioenhancing activity by increasing root and shoot growth, and photosynthetic rate. The PGPR inoculation with 33% N-fertilizer also increased the Ca uptake capacity resulting in higher Ca concentration in root, corm and pulp but increased the Mg concentration in the root only. In addition, the total accumulation of nutrients was heavily influenced by PGPR inoculation due to enhanced root proliferation. The PGPR inoculation greatly increased the bunch yield (35–51%). The strains Sp7 and UPMB10 were evaluated for their N₂ fixing capacities in association with banana roots by ¹⁵N isotopic dilution technique and acetylene reduction assay (ARA). The results conclusively showed that roots of PGPR-inoculated plants fixed N₂ and produced higher ARA values and inoculated plants together with the least N-fertilizer supply showed the highest amount of nitrogen derived from atmosphere (Ndfa). The findings from the above studies demonstrated that PGPR strains (Sp7 and UPMB 10) inoculation with minimal N-fertilizer supply are effective as a bioenhancer for increasing plant growth, nutrient uptake and yield of bananas.     

Effect of interstock (M.9 and M.27) on vegetative growth and yield of apple trees (cv “Annurca”)

With the purpose of obtaining apple plants with reduced vigour but deep and expanded root apparatus, more adapted for establishment of apple orchards in dry, windy areas and higher altitudes, different interstem/rootstock combinations were compared, using seedling as rootstock and, alternatively, two weak interstocks (M.9 and M.27). For all treatments the plants were grafted at two height from soil (10 and 20 cm), interposing interstock 10 or 20 cm long. Plants with interstock showed lower vegetative growth in comparison with control plants with a reduction of 80% (M.27) and of 50% (M.9) of canopy growth. Moreover, use of interstock determined, as compared with the control plants, an increase of fruit production and average fruit weight. It was noted that increasing the interstock length, caused reduction of plants vigour and fruit production. The results showed that, the combination “Annurca Rossa del Sud”/M.9 (10 cm long)/seedling rootstock (20 cm high) was the most efficient for productivity, early maturing and plant vigour control.     

Influence of sprayable mulch colour on yield of eggplant (Solanum melongena L. cv. Millionaire)

Planting beds were treated with sprayable, synthetic latex film (BASF, Charlotte, NC, USA) and oversprayed with black, white, red, blue, yellow or silver oil-based paint to study the effect of coloured spray mulches on yield of eggplant (Solanum melongena L. cv. Millionaire). Nonpainted mulch base and bare ground plots served as control treatments. Individual experimental units consisted of three rows, 102 cm wide × 7.3 m long, transplanted with 8 plants per row. Treatments were replicated in four blocks each at two separate locations near Fresno, CA. Plants grown on silver-painted beds produced significantly greater numbers (42–221%) of fruit and total fruit weight (42–237%) than all other treatments at both locations after eight harvests. Silver-painted mulch stimulated significantly greater flowering and fruit set numbers prior to the first harvest at one site. Apart from silver, only blue- and white-coloured mulches provided increased numbers and/or fresh weight yields at one site only. Mulched plots painted with other colours did not produce yields different from either the bare ground or nonpainted mulch base controls at either site.     

Drying half of the root-zone from mid fruit growth to maturity in ‘Hass’ avocado (Persea americana Mill.) trees for one season reduced fruit production in two years

We tested the effect of extended drying of half the root system on fruit yield and fruit Ca concentration, an indirect measure of fruit quality, in avocado (Persea americana Mill. cv Hass). In a field experiment on a sandy soil, withholding irrigation and plastic sheeting was used to dry the root-zone beneath the whole canopy (DD) or half the canopy (WD), compared with well-watered trees (WW). The irrigation water contained added nutrients and was slightly saline. Yield, shoot growth, leaf conductance, leaf and fruit water status and mineral concentrations of leaves and fruit were studied. The responses of treated trees were assessed in the following season during which normal irrigation practices were restored. With respect to yield, the WD treatment behaved the same as the DD treatment. It reduced yield by more than half and proportionately more than the reduction in water supply thus reducing irrigation efficiency. Re-watering did not restore yield of WD or DD-trees in the next season. The WD and DD treatments had no effect on the concentration of Ca in the fruit mesocarp and so are unlikely to affect fruit quality. The main impact of reduced water supply on the trees was fruit abscission and this was linked to dry soil around the roots rather than the water status of the leaves or fruits. We conclude that extended drying of half of the root-zone in one season reduced irrigation efficiency for two seasons by promoting the abscission of developing fruit to the same extent as occurred when the whole root system was exposed to extended drying.     

Leaf pruning intensities at flowering of banana (Musa AAA,cv. Grande Naine) did not influence fruit green and yellow life and quality

This study examined the effects of leaf pruning intensities at flowering on the green and yellow life and fruit quality of bananas (Musa AAA, cv. Grande Naine). The fruit from banana plants that retained 7, 9, 11 and 13 leaves after pruning were packed in carton boxes of 13.7 kg and stored in a cold room at 14 °C for 21 days to simulate transportation conditions. During this period, eight visual evaluations of fruit peel colour were made. Next, fruits were induced to commercial ripening using ethylene at 100 μl/ml. Four evaluations (every 2 days) on fruit firmness, soluble solids, titratable acidity, fruit weight and peel colour were made to assess fruit yellow life. No interaction between evaluations and number of leaves retained was found for pulp firmness, soluble solid percentage, fruit acidity, fruit weight and maturation grade. The fruit green life and peel colour was similar for plants retaining different number of leaves. After the application of ethylene, there were no differences in fruit firmness (P > 0.62), percentage of soluble solids (P > 0.24) nor in the percentage of acidity (P > 0.32). No difference in fruit weight (P > 0.07) and ripening grade (P > 0.17) were observed among plants retaining different number of leaves. The results suggest that in tropical commercial banana plantations, producing for international markets, it is possible to defoliate the banana plants to seven leaves at flowering without causing a reduction on the green and yellow life and quality of fruit.     

砂糖桔花期及幼果期不同处理对坐果率及产量的影响

为探索砂糖桔高产稳产栽培技术,笔者于2004～2005年对砂糖桔果树花期及幼果期采用不同处理对比试验,为推广应用提供依据.