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 propagation material on some quality attributes of strawberry fruit (Fragaria x ananassa, var. Selva)

In the Mediterranean region, cold-stored plants (summer planting system) are used as the main strawberry planting material (plant establishing period July–August). However, recently fresh plants (winter planting system) have also started being used for strawberry production (plant establishing period October–November). As the plantations originated from cold-stored or fresh plants differ in plant growth and yield, some differences in fruit quality have also been expected; therefore, the objective of the current study was to compare fruit quality of plants originated from different propagation material. Cold-stored plants were well developed before the beginning of the spring harvest, while fresh plants continued growth concomitantly with fruiting. The harvesting period of cold-stored plants lasted 4–6 weeks (second week of April–second half of May). Fresh plants produced fewer and larger fruits than cold-stored plants, but for a longer harvest period, which lasted throughout all summer. Differences in soluble solids and dry matter content between the fruits from cold-stored and fresh plants were observed in the first three sampling dates in both years of the experiment. In some sampling dates, significant differences in anthocyanin, titratable acidity and ascorbic acid content, were observed between fruits of plants originated from different propagation material.     

Influence of fruit load on dry matter and N-distribution in sweet pepper plants

The influence of fruit load on the leaf characteristics and on the distribution of dry matter (DM) and nitrogen (N) in sweet pepper (Capsicum annuum L., cv. Cornado) plants was investigated under Mediterranean glasshouse conditions during a winter–spring production cycle (from December till June). DM weight of all organs (roots, stems + petioles, leaves and fruits) and N content were determined throughout the growing cycle over a 3-week interval. The results showed that the cyclic fruit load pattern (production flushes) was associated with strong variations of N-leaf content on an area basis and specific leaf weight, SLW. On a whole plant scale, the value of SLW dramatically decreased (≈30%) with increasing fruit load; the reverse held true as long as the fruit dry weight remained low (<30 g pl⁻¹). The decline in SLW was coincident with a shift in distribution of DM and N in the plant, both preferentially diverted to the fruits. The time evolution of DM and N fractions in organs exhibited periodic fluctuations, with a duration close to the length of a fruit growth cycle (about 70 days, from anthesis to harvest). Linear relationships were found between the fraction of dry mass and N in fruits, and those of the other organs. The slope of these relationships was considered as an indicator of the response and sensitivity of the organ growth to an increase in fruit load. The root dry mass fraction was the most affected by increases in fruit load (slope of −0.75), while the N fraction in roots and in leaves was affected to a similar extent (slope of −0.50 and of −0.40, respectively). We conclude that, in the sweet pepper, the cyclic pattern of fruit load induces opposite cyclic patterns of dry matter and N content in the other aerial organs as well as in the roots, thereby reflecting close shoot–root coordination in the allocation of carbon and nitrogen resources among the organs. Finally, we discuss the possible implications that could derive from these findings for modelling dry matter partitioning in plants subjected to continuous fruit harvesting.     

‘粤引无核荔’退化果形成原因初探

 对‘粤引无核荔’ (Litchi chinensis Sonn. ‘YueyinWuheli’) 正常果和退化果果皮的内源激素进行测定, 同时比较正常果和退化果结果母枝叶片中的碳水化合物。结果表明, 在谢花后56 d和66 d, 正常果果皮中的IAA /ABA、GA_{1 + 3} /ABA、iPAs/ABA值均高于退化果; 在谢花后56 d, 正常果结果母枝叶片的淀粉含量高于退化果; 在谢花后66 d, 正常果结果母枝的蔗糖含量高于退化果。认为退化果中IAA、GA和细胞分裂素与ABA的比值处于相对低的水平, 以及退化果结果母枝叶片碳水化合物水平相对较低可能是退化果形成的原因。     

Early cell enlargement by night-time heating of fruit produce watermelon fruit (Citrullus lanatus Matsum. et Nakai) with high sucrose content

To investigate the effects of night-time temperature on cell and fruit size, and sugar accumulation in watermelon fruit, fruits were treated with high night-time temperatures in a greenhouse. The minimum night-time ambient temperature of the heating box (18 °C) was approximately 6 °C higher than that of the control. The length, diameter and weight of heat-treated fruit at the end of heating treatment, 16 days after anthesis (DAA), were significantly greater than that of control fruit, but those at harvesting, 42 DAA, were almost the same in both treatments. Mean cell size of the outer portion of heat-treated fruit at 16 DAA was significantly larger than that of the control. Cell size of the fruits at 42 DAA did not differ between heat-treated and control fruits. Sucrose, glucose and fructose content of fruit at 16 DAA did not differ between heat-treated and control fruit. However, sucrose content of the outer portion of heat-treated fruit was 162% of that of control fruit at 42 DAA. Glucose and fructose contents at 42 DAA did not differ between heat-treated and control fruit, except glucose content of outer portion.     

Content levels of various fruit metabolites in the ‘Conference’ pear response to branch bending

The response of ‘Conference’ pear subjected to branch bending in the content levels of various metabolites in its fruit was investigated. The fruits in commercial maturity were sampled in 2004 and 2005 from branches bent in the late summer of 2003 (the summer treatment), from branches bent in the late spring of 2004 (the spring treatment) and from control branches. The content levels of carbohydrates, organic acids and phenolic compounds were compared among treatments in two successive years. The fruit revealed various responses in content levels of metabolites. In the first year after bending, no significant differences were found in the content of each carbohydrate, but in 2005 by far the highest content level of glucose and fructose and the lowest content level of sucrose were found in fruits from the control. The control fruit showed significantly higher content levels of malic acid and lower content levels of some phenolics (chlorogenic and vanillic acid) in the first year after bending, but in the next year the opposite reaction occurred—the control fruit had the lowest content level of malic acid and the highest content level of epicatechin, quercetin-3-d-galactoside and quercetin-3-β-d-glucoside. The comparison of the two bending treatments alone in 2004 showed that the summer treatment often produced a slightly higher value of each phenolic in comparison to the spring treatment. However, in 2005 the significantly highest content of chlorogenic acid was in fruit from the spring treatment. Sorbitol, as well as citric acid, catechin and sinapic acid showed no clear tendency among treatments, neither in 2004 nor in 2005. It is suggested that these variations of ‘Conference’ fruit subjected to different bending treatments could not be the result of bending alone, but that they could be indirectly affected by other physiological responses of the fruit tree. However, it seemed that variations are affected by the time of bending and by the year-to-year, and such responses can be attributed to the ‘Conference’ genotype only.     

Effect of pollination on cell division,cell enlargement,and endogenous hormones in fruit development in a gynoecious cucumber

To study the effect of pollination on fruit development in gynoecious and parthenocarpic cucumbers (Cucumis sativus L. cv. NK × AN8), the number of cells, cell size, mitotic index, histone H4 gene expression, and concentrations of endogenous cytokinins and auxin were compared in fruits that had developed from pollinated and non-pollinated flowers. Fresh weight was more in the pollinated group 4–12 days after anthesis (DAA) in both winter and spring, and 2–6 DAA in the summer. In winter, mitotic index increased from anthesis to 2 DAA and then decreased gradually in the pollinated group but immediately after anthesis in the non-pollinated group. Histone H4 gene in the pericarp zone was expressed more strongly during the period from pre-anthesis to 2 DAA in the pollinated group in summer. Concentrations of zeatin, isopentenyladenine, and indole-3-acetic acid (IAA) were higher in the non-pollinated group 2 and 4 DAA and peaked 4 DAA in spring whereas isopentenyladenine and IAA showed no distinct peaks in the pollinated group. These results are incompatible with the idea that pollination activates cell division by stimulating the synthesis of cytokinins and auxin in cucumber fruits.     

Changes in fruit maturity indices along the harvest season in ‘Algerie’ loquat

Loquat is a subtropical fruit tree that presents an annual cycle reverse to that of the well-known temperate fruit crops. Loquat rests during summer, blooms in autumn, develops its fruit through winter and ripens them in early spring. Its unusual phenology allows growers to obtain high prices for its fruits, especially for early harvests. Although loquat is harvested based on skin colour, a minimum soluble solid content (TSS) of 10° Brix is often required for commercialization. However, we have noticed that the relationship between skin colour and eating quality seems to change along the season leading costumers to complain for the high acidity of the earliest fruits. In order to establish a reliable maturity index, we have evaluated the changes in different fruit maturation parameters along the harvest period in four consecutive seasons for ‘Algerie’ loquat. The results show that in samples collected with similar skin colour, TSS and, especially, fruit titratable acidity (TA) tend to decline as harvest season progresses. This makes fruit skin colour on its own not suitable as a harvest index to assure an adequate fruit quality under all circumstances. We propose instead to monitor continuously TSS and TSS/TA ratio along the season in order to fulfill consumer's expectations.     

影响南京甜樱桃坐果的关键时期

研究不同生育期的生态条件对甜樱桃花芽分化和坐果的影响,确定导致南京地区（年均温 > 15 ℃）甜樱桃坐果率低的关键时期,将郑州的一部分4年生盆栽结果甜樱桃运至南京生长1年后,然后将郑州和南京两地的盆栽苗分别在落叶期、休眠结束后进行双向位置交换,采用石蜡切片法观察花芽和胚囊形态发育,并在果实着色期观察坐果率。结果显示：全生育期在郑州、落叶期由郑州运至南京、休眠结束后由郑州运至南京、全生育期在南京、落叶后由南京运至郑州的‘早红宝石’甜樱桃坐果率分别为38.2%、14.7%、12.9%、8.9%和31.7%;无胚囊的比例分别为41.5%、55.6%、57.7%、74.5%和50.0%;全生育期在郑州和落叶后由郑州运至南京休眠结束后再运回郑州的甜樱桃‘萨米脱’的坐果率分别为13.9%和18.8%。结果表明：影响南京地区甜樱桃坐果的关键时期应是春季开花坐果期;而对于一些能满足需冷量的品种,休眠期对坐果率的影响不大;夏季花芽分化期的高温影响花芽分化进程及分化质量。     

The influence of irrigation system and nutrient solution concentration on potted geranium production under various conditions of radiation and temperature

Zonal geranium (Pelargonium × hortorum ‘Real Mintaka’) were grown in closed soilless systems to evaluate the effects of irrigation system (drip and subirrigation) and nutrient solution concentration (half and full) under various conditions of radiation and temperature (winter and summer) in terms of substrate electrical conductivity (EC_s), growth, quality, crop evapotranspiration (ET_c) and growth index water use efficiency (WUE_GI) and nutrient uptake. At he end of the cultural cycle the highest EC_s in the upper and lower layers were recorded in the spring season on plants grown in subirrigation using a full nutrient solution concentration. The highest shoot biomass, leaf area, plant growth index, and quality index were recorded in the winter season on plants grown in both drip-irrigation and subirrigation using half and full nutrient solution concentration, whereas the lowest value was observed in the spring season on plants grown with subirrigation using the full nutrient solution concentration. The highest maximum air temperature recorded during the first 20 days after transplanting in the spring growing season was presumably responsible for the reduction in shoot biomass production, growth and quality index, and in time of geranium flowering compared to the plants grown in the winter season. The ET_c was 44% higher in spring than in winter season treatment, while the effect of the irrigation system was less pronounced with an increase in 11% in the subirrigation treatment compared with the drip-irrigation system. WUE_GI was not stable and showed a seasonal variability. Solar radiaton (R_s), air temperature (T_a) and vapour pressure deficit (VPD) were greatly higher in the spring season, which influenced WUE_GI negatively. The WUE_GI improved especially when R_s, T_a and VPD were below 12 MJ m², 20 °C and 0.6 kPa, respectively. The highest N, and Mg uptake were recorded in the winter season, especially on plants grown with subirrigation at 2 dS m⁻¹. The highest P, K, and Ca uptake values were measured during winter season using subirrigation system, and on plants grown under full strength nutrient solution. The variation of the nitrate concentration and EC in the nutrient solution during the spring growing cycle was less pronounced in the subirrigation than with a drip-irrigation system which represents an important aspect for the simplification of the closed loop management of the nutrient solution.     

砧木对小型早熟西瓜果实糖代谢及相关酶活性的影响

 以小型西瓜品种‘小兰’自根植株为对照, 研究‘杭州长瓠’、‘超丰F₁’、‘勇士’、‘黑籽南瓜’4 种砧木对其果实糖代谢特性及相关酶活性的影响。结果表明: 4 种嫁接西瓜果实发育过程中蔗糖、葡萄糖、果糖含量和糖代谢酶活性变化趋势与自根西瓜一致。在果实发育早期, 果实中以分解酶类为主, 糖分积累低; 发育后期以合成酶类为主, 糖分积累多。西瓜嫁接后果实糖分含量明显降低, 降低程度依砧木而异, 超丰F₁/ 小兰、杭州长瓠/ 小兰西瓜的糖含量明显高于黑籽南瓜/ 小兰、勇士/ 小兰。砧木可能主要通过影响果实发育早期转化酶( Inv) 、发育后期蔗糖磷酸合酶(SPS) 、蔗糖合酶(SS) 活性来影响糖分积累。各处理糖代谢酶的净活性与糖分积累存在较好相关性, 说明糖代谢酶在西瓜果实糖分积累中的作用是综合的, 造成自根及嫁接西瓜果实糖分积累的差异是Inv、SPS、SS 几种酶共同作用的结果。     

樱桃番茄果实风味分析

对 8个适期成熟的樱桃番茄果实还原糖、蔗糖、可溶性糖和可滴定酸进行了分析 ,结果表明 :还原糖是樱桃番茄可溶性糖的主要组成部分 ,蔗糖含量很低 ;秋季果实可滴定酸含量远高于春季 ;土壤栽培果实可溶性糖含量高于无土栽培 ;樱桃番茄果实风味主要取决于可溶性糖和可滴定酸的绝对含量 ,与糖酸比关系不大。     

The Effects of Manurial Treatments on the Chemical Composition of Gooseberry Bushes.: I. Effects on Dry Matter,Ash and Ash Constituents of Leaves and Stems of Terminal Shoots and of Fruits; and on Total Nitrogen of Fruits.

Summary

The effects of different timings of fruit thinning at the lower nodes (nodes 4 to 7) on fruit growth and abortion at higher nodes were investigated in a gynoecious, parthenocarpic cultivar of cucumber (Cucumis sativus L.), ‘NK x AN8’. Fruits at the lower nodes were removed 0, 5, 10, 15 and 20 d after anthesis of flowers at node 8 (DAA₈).

Total leaf areas and growth patterns of individual fruit were then monitored. When fruits at nodes 4 to 7 were thinned 0 or 5 DAA₈, all fruits at nodes 8 to 12 grew to commercial size, without fruit abortion. When fruits were thinned 10 DAA₈, the fruits at nodes 8 to 12 ceased to grow after anthesis, but growth was restored a few days after fruit thinning. Fruit thinning at 15 or 20 DAA₈ forced most fruits at nodes 8 to 12 to abort, while fruits at node 13 and above ceased to grow for a while, but resumed growth after fruit thinning. In all treatments, total leaf area increased with time throughout the experiment. High fruit load depressed the rate of growth of leaf area slightly, 65 to 75 d after sowing. Fruit load (fresh weight) per leaf area was about 50 mg cm^–2 just before fruits at nodes 4 to7 were thinned at 20 DAA₈.These results suggest that fruit abortion occurs if fruits at the lower nodes persist for a long period, and fruits at the middle nodes senesce before enlargement. Fruit thinning at the lower nodes can restore the growth of fruits in the stagnant growth phase within 10 d.     

Biomass yield and accumulations of bioactive compounds in red amaranth (Amaranthus tricolor L.) grown under different colored shade polyethylene in spring season

Biomass yield and accumulations of betacyanin, chlorophyll, total polyphenol, and antioxidant activity were evaluated growing red amaranth (Amaranthus tricolor L.) in spring season under five different shades made of white, blue, green, yellow, and black polyethylene, and non-shaded frame. Temperature and light intensity varied significantly (P < 0.05) under the different colored polyethylene shades, and these differences in microclimate are implicated for the variability in growth and accumulations of bioactive compounds. The highest temperature was obtained under the blue polyethylene shade and the plants achieved highest plant height, stem length and leaf number, fresh and dry matter biomass, betacyanins, total polyphenol, and antioxidant activity. The achieved biomass yield and accumulation of bioactive compounds were almost similar to field grown red amaranth in summer season. Blue polyethylene shade has probably ensured the optimum microclimate for growth and development of red amaranth in the studied growing period. Exceptionally the plants grown under green polyethylene shade accumulated highest chlorophyll. Although non-shaded plants received highest sunlight intensity but gave the poor biomass yield as well as accumulated less bioactive compounds than plants grown under blue polyethylene shade due to low air temperature. Thus, the results indicated that blue polyethylene has potentials to increase the yield with health beneficiary bioactive compounds betacyanins, polyphenol and antioxidant activity during the low temperature regime in spring season.     

Abortion of reproductive organs in sweet pepper (Capsicum annuum L.): a review

Summary

Levels of abortion of reproductive organs (i.e., buds, flowers, and young fruits) in sweet pepper plants (Capsicum annuum L.) are high, and cyclical fluctuations occur in fruit set. Stages susceptible to abortion are very young buds (< 2.5 mm), buds close to anthesis, and flowers and fruits up to 14 d after anthesis. An overview of factors and processes involved in flower and fruit abortion in sweet peppers is presented. More light, higher CO₂ concentrations, and lower planting density, increase the availability of assimilates per plant, and decrease fruit abortion. The cyclical pattern in fruit set is caused by changes in demand for assimilates. High flower abortion occurs when fast growing fruit (at approx. 3 weeks after anthesis) are present, due to competition for assimilates. Fruit set increases when fast growing fruit are almost mature and have a low assimilate demand. Prior to abortion, auxin export from the reproductive organ diminishes, ethylene production increases, and lower levels of activity of sucrose-cleaving enzymes are found. Severe water stress and low nutrient supply also increase abortion levels. Low night- and high day-time temperatures hamper pollen development, causing low seed set, which can result in fruit abortion. Two theories have been used to explain abortion: unbalanced demand for and supply of assimilates, and hormonal dominance of developing fruit over young fruit. Attempts to prevent abortion or to diminish the cyclical pattern of fruit set have not yet been successful, but new suggestions are presented.     

闽西北桃小叶症病因诊断与区域性骤发诱因

2003—2005年闽西北桃产区大范围骤发"桃小叶症",典型症状为春梢展叶期叶片不能正常伸展,病叶狭小细长,呈丛生莲座状、花萎无果,各主栽品种均同时受害。经研究该病嫁接不传染,且经2年20个重复的发病果园病株叶片分析,含B≤9.71mg/kg,远低于适宜值下限20mg/kg,结合生殖障碍等形态症状与施B矫治疗效,诊断"桃小叶症"为重度缺B症。再则,根据萌芽期2月至翌年4月发病期各时段雨量与次年发病率的滑动相关分析还表明,中亚热带季风红壤缺B≤0.45mg/kg地区,桃生长季2月中旬—9月上旬的严重干旱是引发翌年桃小叶症区域性骤发的诱因,而非发病季当年春季的降水不足;同时由同类土壤的模拟干旱试验还表明,高温、干旱并不导致同类土壤热水溶性B明显下降,干旱对桃B吸收障碍另有原因。还就桃小叶症矫治提出相应措施。     

Pollination and Environmental Factors Affecting Fruit-Setting in Spencer Sweet Peas,Lathyrus Odoratus L.

Hand pollination, flower-shaking or tripping of the keel petals, was necessary to obtain adequate self-pollination of Spencer type sweet peas in glasshouses.

The effect of low light intensities on fruit-setting was studied by growing plants under muslin of different weaves. During long days a small but significant increase in the fertility of a summer-flowering variety of sweet pea occurred on plants shaded by thin muslin, provided that high temperatures and minimal soil watering were maintained. The more intense the shading treatment, the greater was the amount of flower-bud abortion and this abortion was responsible for lower yields of fruits per plant. A significantly smaller number of flowers set fruit as a result of a heavy watering treatment that led to a slight waterlogging in the pots.

By comparing the fruit-setting rate with temperatures which prevailed in a series of five-day periods in spring and summer, it was found that, for unit rises of temperature, the setting rate increased exponentially. A regression equation was computed for the prediction of setting rates.

Low temperatures in the week before anther-dehiscence were found to depress fertility, no matter how favourable the post-pollination temperatures.     

Forcing vine regrowth and shifting fruit ripening in a warm region to enhance fruit quality in ‘Cabernet Sauvignon’ grapevine (Vitis vinifera L.)

Summary

In warmer regions, winegrapes ripen their fruit during the hottest portion of the growing season, producing wines of high pH, low acidity, less intense colour, and a less complex flavour. Experiments were conducted in a commercial vineyard of ‘Cabernet Sauvignon’ at Fresno, CA, USA in 2009, and in 2010, to determine if vines could be forced to enhance fruit quality. Forcing was conducted by hedging growing shoots to six nodes and removing summer laterals, leaves, and primary clusters between 14 – 70 d after anthesis in late-May, June, and July. Vines grown under conventional practices were used as controls. Forcing in June shifted fruit ripening from the hot (July and August) to the cool (October through early-November) portion of the growing season, a period with more hours at lower, more favourable temperatures. Fruit from the forced crop had smaller berries, a lower pH, higher acidity, and higher contents of anthocyanins, tannins, and total phenolics, compared with non-forced fruit. The yield and vigour of forced vines were comparable to, or slightly lower than, control vines. The best forcing treatment consisted of hedging growing shoots to six nodes and removing summer laterals, leaves, and primary clusters. Our study demonstrates the potential of forcing to address the detrimental effects of high temperatures on fruit quality in warmer regions of winegrape production.     

苹果果实套袋对光合同化物积累与转化的影响

 通过建立一定的源库单位,分析富士苹果套双层纸袋后果实库中光合同化物的积累与转化代谢的动态变化。结果表明：套袋45 d（盛花后90 d）后,果实中光合同化物山梨醇的积累量明显高于未套袋的对照,但淀粉、葡萄糖、果糖、蔗糖含量低于对照;与糖转化代谢相关的蔗糖合酶（SS）、蔗糖磷酸合成酶（SPS）、酸性转化酶（AI）、山梨醇脱氢酶（SDH）和淀粉酶的活性均低于对照。套袋降低了果实的库活力,减弱了调运养分的能力。     

Use of paclobutrazol sprays at mid-anthesis for increasing fruit size and yield of avocado (Persea americana Mill. cv. Hass)

Mid-anthesis foliar sprays of paclobutrazol (PB) at 2.5, 1.25 and 0.62 g a.i. I-1 reduced spring growth and altered dry-matter distribution in fruiting spring shoots of ‘Hass’ avocado.(Persea americana Mill.) trees. There was a decrease in dry matter allocation to vegetative components and an increase in allocation to fruit. The starch concentration in the wood of spring shoots on trees treated with 2.5 g a.i. I-1 foliar PB was increased by ca. 70% compared with spring shoots from trees of other treatments. The mid-anthesis foliar treatments also reduced summer growth by ca. 20%. Trunk injection of PB at 0.2 g a.i. m~2 of canopy silhouette area when the spring growth matured, in addition to a mid- anthesis foliar spray of 1.25 g a.i. I-1, reduced the length of summer shoots by 36% when compared with untreated trees. The spray treatments of 2.5 and 1.25 g a.i. T1 PB at mid- anthesis increased the mean fruit size at harvest by 16 and 11% respectively. Fruit yield was not significantly affected by PB applications on an annual basis. However, the PB spray treatments of 1.25 and 0.62 g a.i. I-1 significantly increased the two year cumulative yield by ca. 63%. There was no significant effect from the trunk injection treatment on fruit yield in either the season of treatment or the following season.