Branching habit of 2-year-old pear branches classified on the basis of length and position of 1-year-old laterals

Two-year-old branches of Pyrus communis L. were classified into groups according to the proleptic (from dormant buds) branching habit, indirectly quantifying the degree of apical control. In winter 1998 upright and flat, 2-year-old branches were randomly sampled from trees of seven pear cultivars, i.e., Forelle (on Quince A and BP1 rootstocks), Abaté Fetel, Flamingo, Packham’s Triumph, Golden Russet Bosc, Rosemarie and Beurre D’Anjou on BP1 rootstock. For each branch the length and position of the 1-year-old shoots on the 2-year-old axis was determined. Laterals were classified according to length (<1, 1–5, 5–20 and >20 cm) and position (distal to proximal quadrants on the 2-year-old axis); 16 classes in total. The number of shoots per length class per cm quadrant length for each cultivar was subjected to a cluster analysis, then a canonical and a stepwise discriminant analysis. The cultivars were grouped into four groups from group 1 (‘Flamingo’), which resembles a spurred growth habit with strong apical control, to group 4 (‘Packham’s Triumph’ and ‘Golden Russet Bosc’), which resembles a spreading growth habit and weak apical control. Groups 2 and 3 were intermediate. The gravimorphic influences on the branching habit were investigated.     

Subject Index

Prohexadione-calcium (ProCa) is a gibberellin biosynthesis inhibitor with limited persistence and low toxicity that has recently been registered as a shoot growth retardant for apples in North America (Apogee^®) and Europe (Regalis^®). We investigated the response of six different pear cultivars (‘Rosemarie’, ‘Forelle’, ‘Packham's Triumph’, ‘Flamingo’, ‘Early Bon Chretien’ and ‘Golden Russet Bosc’) to ProCa in the Western Cape, South Africa, over the period 1999–2003. ProCa treatments ranging from 50 to 250 mg l⁻¹ were applied between one and three times per season and were compared with girdling and control treatments. ProCa application reduced shoot growth in all of the cultivars. ‘Forelle’, was least responsive and showed a reduction in 2002/2003 but not 2001/2002. ‘Rosemarie’, ‘Flamingo’, ‘Packham's Triumph’ and ‘Golden Russet Bosc’ were most responsive, with shoot growth being reduced by up to 50% of the control for the latter two cultivars. The response to number of applications and ProCa concentration was not consistent across cultivars. ‘Early Bon Chretien’, for example, only responded to high ProCa concentration, whereas ‘Rosemarie’ was very responsive at the lowest ProCa concentration. ProCa application improved fruit set but decreased final fruit size in some of the cultivars, particularly in ‘Rosemarie’. It also caused a decrease in return bloom in ‘Forelle’ and ‘Packham's Triumph’. The response of different cultivars to girdling, in terms of shoot growth and fruit set was highly variable. Girdling tended to increase final fruit size and return bloom. ProCa shows potential as a shoot growth retardant for the pear cultivars investigated, but the response of reduced fruit size in some cultivars requires mitigation. Future research on combined girdling and ProCa treatments may be instructive.     

The Uptake of Metallic Ions by Leaves of Apple Trees: II. The Influence of Certain Anions on Uptake From Magnesium Salts

Mechanical thinning of cv Delicious apples six to ten weeks after full bloom eliminated the need for hand thinning. Fruit removed earlier than six weeks would have shed naturally. Fruit removed after ten weeks was poorly distributed as increasing fruit weight caused the fruiting laterals to hang lower than 45° from the vertical. Mechanical thinning was non-selective for fruit size. Of five pear cultivars examined, Williams, Josephine and, to a lesser extent. Beurré Bosc could be mechanically thinned successfully. The long flexible peduncle was a major limitation in mechanically thinning Packham’s Triumph pears. Mechanical and hand thinning were equally effective in reducing the proportion of small fruit in Williams pears.     

The effect of rootstock shoot growth on the level of bud-grafting success in apple

Poor stands of ‘Queen Cox’ apple bud-grafted in summer onto M.9 rootstock were shown to be due to the scion bud not growing, or growing too late to produce a worthwhile ‘maiden’ tree, despite virtually all scion graft-chips forming unions with the rootstock. This problem was caused by raising the budding height to 30 cm above ground, as a method of increasing the height of lateral branches. The key element in higher budding which depressed subsequent scion bud growth was the complete removal of all rootstock shoots to a height of 35 cm to give a traditional ‘clean leg’ during the budding year. Removing rootstock shoots only at the budding position gave good stands of high quality trees. This appears to be a general effect, with the benefits of retaining rootstock shoots applying also to Malus tschonoskii when budded at 30 cm on M.9 rootstock. For both ‘Queen Cox’ and M. tschonoskii, failure of scion buds to grow vigorously often resulted in the development of ‘papery bark canker’ on the M.9 rootstock. The main benefit of root- stock shoots retained in the budding year was to ensure that scion buds grew early in the following ‘maiden’ year, whereas allowing these and new rootstock shoots to remain for the first two months of ‘maiden’ growth reduced the number of secondary scion buds which developed, and raised the height of laterals by delaying their emergence.     

Multiformulation dips for controlling storage disorders of apples and pears. I. Assessing fungicides

When applied as post-harvest dips on ‘Granny Smith’ or ‘Jonathan’ apples and ‘Packham Triumph’ pears, the fungitoxic effect of Benlate, Rovral, Dithane M45 or Imazalil was not adversely affected by the presence of diphenylamine or calcium chloride. Best protection from storage rots was obtained with Rovral and Imazalil on ‘Granny Smith’; Benlate, Rovral and Imazalil on ‘Jonathan’ and Rovral or a Dithane M45 Benlate mix on ‘Packham’ pears. Calcium chloride in these dips reduced ‘Jonathan’ breakdown and when mixed with Benlate, Rovral or Imazalil, it improved retention of fruit firmness. A disadvantage of calcium chloride in dips was its effect of increasing skin injury (lenticel spot) on ‘Granny Smith’ and ‘Jonathan’. Scald control by diphenylamine was unaffected by the presence of calcium chloride or fungicides.     

The rest period of pecan in Egypt

Pecan trees cv. ‘Moneymaker’ and seedling trees growing in Northern Egypt were sprayed with dinitrocresol mineral oil emulsion, to test its effect on male and female flower bud growth, flowering and fruiting. The treatments had a stimulating effect on growth of male and female flower buds. The treated trees flowered from 1 to 3 weeks earlier than the control. Fruit drop was greatly reduced and, consequently, fruit yield was remarkably increased.     

The influence of fruiting on the bud sprouting and flower induction responses to chilling in Citrus

Summary

The effect of chilling temperatures on bud sprouting and flower formation was compared on fruiting and non-fruiting ‘Owari’ satsuma mandarin (Citrus unshiu Marc) trees. On non-fruiting trees, bud dormancy was weak, and a significant proportion of buds were able to sprout at high temperatures without being chilled. Separate effects of low temperatures on bud sprouting and flower induction were demonstrated. On fruiting trees these two effects of low temperatures were also demonstrated on summer-flush buds, but not on older (spring-flush) buds. The spring-flush buds from fruiting trees scarcely sprouted without being chilled. These buds required a longer chilling period for dormancy release than for flower induction, and it was not possible to separate the effect of low temperature on flower induction from the effect on dormancy release. The presence of fruit reduced flower formation by reducing bud sprouting. Furthermore, fruit had a direct inhibitive effect on vernalization which resulted in increased formation of vegetative shoots. The effect of fruit and low temperature on flowering was unrelated to carbohydrate accumulation in the leaves or the roots.     

Effects of pruning intensity on the biochemical status of shoot buds in three mango (Mangifera indica L.) cultivars planted at high density

Summary

Mango (Mangifera indica L.) trees grown at high density show a decline in flowering and fruiting after good fruiting years as a result of various factors. Annual pruning can restore production and productivity in such trees. Chlorophyll, total sugars (TS), total phenolics (TP), and proline contents as well as polyphenol oxidase (PPO) activities, were measured in the 2005–2006 and 2006–2007 seasons in shoot buds with a few leaves in three mango cultivars (‘Amrapali’, ‘Mallika’, and ‘Dashehari’). Trees were grown at high density in an orchard and the aforesaid parameters were measured 1 month after different degrees of pruning (Stage I) and after subsequent fruit bud differentiation (FBD; Stage II). Severely-pruned mango trees had the highest contents of chlorophyll a, while chlorophyll b and total chlorophyll contents were found to be highest in moderately-pruned trees. Lightly-pruned trees had the highest contents of reducing sugars (RS), whereas TS contents were highest in severely-pruned trees. The contents of RS and TS increased in shoot buds during the FBD stage. A moderate intensity of pruning significantly increased TP contents, while the lowest TP contents were recorded in non-pruned trees. ‘Off’-year shoots had higher TP contents than ‘on’-year shoots. Irrespective of pruning intensity, shoot buds of ‘Mallika’ trees had the highest PPO activities, with lower levels in ‘Amrapali’ and ‘Dashehari’ shoot buds. PPO activities were reduced at the FBD stage in ‘on’-year shoots. Severely-pruned trees had the highest PPO activities, while the lowest PPO activities were recorded in lightly-pruned trees. Shoot bud proline contents were found to be highest in non-pruned trees, and decreased with increasing pruning intensity. Thus moderate pruning can be adopted in high density orchards to obtain sustainable production with improved maintenance of canopy architecture.     

Rootstock influence on leaf and fruit mineral status of ‘Bartlett’ and ‘d'Anjou’ pear

In a test with ‘Bartlett’ and ‘d'Anjou’ pear on 8 Pyrus (P.) rootstocks, leaves of ‘Bartlett’ were high in S and Fe on ‘Bartlett’ seedlings (BS), in Zn on P. ussuriensis Maxim. seedlings (USS), and in B on seedlings of P. calleryana Decne (Cal). Leaves of ‘d'Anjou’ were high in P, Zn and B on BS, in N on USS, and in S on Cal. Both ‘Bartlett’ and ‘d'Anjou’ were high in K and Ca on P. betulaefolia Bunge seedlings (Bet). Fruit of both ‘Bartlett’ and ‘d'Anjou’ were high in N, K and Mg on Bet and Cal and high in Ca on Cal and USS. With both ‘Bartlett’ and ‘d'Anjou’, moderately high correlations were found between leaf and fruit concentrations of K and Mg; positive correlations were high for Ca and S with ‘Bartlett’ and for Zn and B with ‘d'Anjou’. There was a very high negative correlation between leaf and fruit Ca with ‘d'Anjou’.     

Temperature effects on dormancy,bud break and spear growth in asparagus (Asparagus officinalis L.)

Summary

The effects of the length of chilling, chilling temperature and growing temperature on dormancy of asparagus crown buds and subsequent rates of spear growth were examined. The results showed that prior chilling enhanced bud break at low growing temperatures and stimulated the growth of spears.Thus, chilling should facilitate commercial production by hastening bud break and spear growth rates at lower temperatures. If sufficient chilling was given, the minimum temperature for rapid bud break was approx. 12.5°C for ‘Rutgers Beacon’ and ‘Jersey Giant’, and around 10°C for ‘UC 157’ and ‘Apollo’. The optimum chilling temperature appeared to be closer to 5°C than to 10°C or 2°C for ‘Rutgers Beacon’ plants grown at 12.5°C. Increasing the growing temperature had a significant effect on the relative spear growth rate (RSGR) in all cultivars. Prior chilling had no effect on the RSGR for ‘Dariana’ and ‘Apollo’; but, for ‘UC 157’, chilling plants at 5°C for 5 or 10 weeks increased growth rates at 12.5°C and at 20°C. These results demonstrate that release of bud dormancy and spear growth rates depended not only on the growing temperature, but also, at least in some cultivars at some temperatures, on the duration and temperature of chilling during the previous Winter.     

‘四季桂’不同季节的花芽分化与发育比较

利用显微解剖和石蜡切片技术,对四季桂品种群中‘四季桂’(Osmanthus fragrans‘Sijigui’)不同季节的花芽分化及开花特性进行研究。‘四季桂’一年成花3次,分别于3月初、6月上旬和10月底开始花芽分化,4月下旬、8月底和11月底完成,分别历时约2个月、2个半月和1个月。6月开始的花芽分化和开花过程与秋桂品种群基本相似,分化后需要低温才能开花,最终形成聚伞花序,无总梗,花粉发育正常。而10月底分化的花芽在完成分化后随即开花,形成的花序有总梗,且有伸长与未伸长之分,长度分别为(0.80±0.11)cm和(3.50±0.71)cm。3月分化的花芽与新梢同时生长发育,分化完成后随即开花。春季和冬季的两次分化形成的均是圆锥状花序,具总梗,花粉均败育。结果表明‘四季桂’自身存在着不同的成花机制。     

Inhibition of flowering of Mexican- and Guatemalan-type avocados under tropical conditions

Avocado trees of a range of cultivars growing in Darwin, northern Australia (average yearly maximum 33°C, minimum 23°C), were observed for flower and shoot development. Terminal buds of the cultivars ‘Fuerte’, ‘Rincon’ and ‘Edranol’ sampled in July were not floral. Buds which did not burst were sampled in September and they contained developing flowers with perianth primordia. Vegetative extension growth resulted from laterals proximal to the inhibited terminal buds.Avocado trees of the cultivars ‘Fuerte’ and ‘Hass’ which had initiated floral buds were transferred to controlled environment chambers with 33°C day, 23°C night ($\text{33}\text{23}$) or 25°C day, 15°C night ($\text{25}\text{15}$) with a 12-h photoperiod and photon flux density of 400 μmol m^?2 s^?1 (400–700 nm). At $\text{33}\text{23}$ the trees had fewer flowers and a shorter flowering period than at $\text{25}\text{15}$. Inhibited floral buds and lateral vegetative extension resulted at $\text{33}\text{23}$, as observed in northern Australia. The unburst buds had developing flowers with perianth and stamen primordia.The controlled environment experiments showed that the abnormal flushing behaviour of Mexican- and Guatemalan-type avocados growing in northern Australia was due to high temperature. Floral development was inhibited at the stage of stamen differentiation.     

纬度和海拔对主要苹果品种花芽分化期的影响

花芽分化调控是苹果优质高产高效栽培的关键环节之一,准确把握花芽分化时期是精准调控的前提和基础,为探究纬度和海拔对苹果花芽分化期的影响,在陕西省杨凌示范区、甘肃省静宁县和四川省茂县3个苹果产区,用摘叶和摘果的方法研究了茂县(海拔1 425、1 680和2 050 m)、静宁(海拔1 601 m)‘长富2号’苹果,杨凌地区(海拔525 m)‘长富2号’、‘烟富6号’、‘嘎拉’和‘秦冠’苹果的花芽分化差异。结果表明:在杨凌地区花芽生理分化的时间为‘长富2号’56 d,‘烟富6号’49 d,‘嘎拉’56 d,‘秦冠’42 d。在茂县不同海拔试验点,‘长富2号’花芽生理分化期持续的时间长短为低海拔高海拔(海拔1 425 m试验点为75 d,1 680 m为70 d,2 050 m为65 d)。‘长富2号’在不同地区,花芽分化持续时间的长短为低纬度高纬度[茂县(31o33′N)为70 d,杨凌(34o18′N)为56 d,静宁(35o41′N)为49 d]。枝条停长时间与花芽分化密切相关,枝条停长越晚越不易形成花芽。在高纬度和高海拔地区枝条停长晚,但是花芽分化持续时间相对短。‘嘎拉’和‘长富2号’花芽分化从6月初开始至10月底分为6个时期,每个时期有明显的特征,各个时期相互交叉重叠;‘长富2号’各分化时期比‘嘎拉’开始的早,结束的晚,并且持续时间长,相对分散,认为这可能与富士苹果成花难有关。     

Carbohydrate content of inflorescent buds of defruited and fruiting pistachio (Pistacia vera L) branches in relation to biennial bearing

Summary

Changes in carbohydrate content of inflorescent buds of fruiting and defruited branches of the same tree were measured in 1994 and 1995 in the period before and during bud abscission in pistachio (Pistacia vera L. cv. Aegenes) to investigate its relationship to inflorescent bud abscission. HPLC was used for soluble sugar analysis, while starch was hydrolyzed to glucose enzymatically and the amount of glucose was then determined using the glucose oxidaseperoxidase method. The effect of fruit on leaf net photosynthesis (Pn), chlorophyll a and b (Chl (a+b)) in leaves and specific leaf weight (SLW) was also investigated in 1995. Starch concentration was initially similar in buds of fruiting and defruited branches but became greater in buds of defruited branches from early June 1994 (57 d after full bloom (AFB)) and 20 June 1995 (61 dAFB), resulting in higher starch contents. Glucose and fructose concentrations were similar in flower buds throughout the whole period of measurement; inositol and sucrose (the most abundant sugar in flower buds) both became much lower in fruiting branches from early July 1994 (83 dAFB) and mid July 1995 (88 dAFB). The rapid decrease in sucrose concentration coincided with rapid seed growth and the greatest period of bud abscission in fruiting branches. During the same period, total sugar and total carbohydrate concentrations and contents were greater in buds of defruited branches. The presence of fruit increased Chl (a+b) content in leaves while decreasing SLW between 43 and 61 dAFB. During this same period, leaf Pn rates were greater in fruiting shoots than in defruited ones.     

山茶花新品种‘花早春’

‘花早春’是由‘早春大红球’芽变选育而来的山茶新品种,耐寒性强。植株直立紧凑,叶片椭圆形。花径15 ~ 18 cm,花蕾簇生于枝条顶部,花期12月下旬—翌年2月底。     

核桃雌雄异熟型品种花芽分化期叶片和芽内源多胺含量的变化

 以核桃雌先型品种‘中林5号’和雄先型品种‘辽宁1号’为试材, 研究了花芽分化期间叶片和混合芽内源多胺的变化。结果表明, 雌先型品种‘中林5号’叶片内Put、Spd含量高峰比雄先型品种‘辽宁1号’提前1周出现; 混合芽内Put、Spd、Spm在所测定时期内动态变化相似, 但含量达最高峰的时间前者比后者提早两周。     

单株留芽量及结果母枝剪留长度对猕猴桃结果性能的影响

对栽植株行距3m×4m的美味猕猴桃秦美品种连续进行了3年试验,单株分别剪留250、300、350、400个芽处理后,平均单株新梢数、叶面积指数、落叶率与留芽数量呈正相关,叶幕下层的光强度、净光合率与留芽数量呈负相关;单株果枝数、果实数及单位面积产量均以留400芽处理最高,但平均单果重最小,88g以上的优质果产量最低。综合评价以单株剪留350个有效芽的效果最佳,优级果产量达到2102.7kg/666.7m2。结果母枝分别剪留7、12、17个有效芽处理后,平均每母枝的结果枝数、果实数、产量与留芽数量呈正相关,均以17芽处理最高,分别达到9.5个、30.4个和3.09kg,各处理间的单果重差异不显著。     

Determination of Heat Requirements and Effective Heat Summations of Some Pomegranate Cultivars Grown in Southern Anatolia

Temperature (high and low) is one of the most limiting environmental factors for growth and production of fruits in different parts of the world. For temperate-zone fruit species, a certain total heat requirements are needed in order to obtain ripe fruits. The aim of this study was to determine heat requirements of three commercial pomegranate cultivars (‘Suruc’, ‘Katirbasi’ and ‘Hicaznar’) grown in Southern Anatolia region. The cultivars showed a narrower range of heat requirements for flowering (growing degree hours, GDH), i.e. ‘Suruc’ (25,000), ‘Katirbasi’ (25,270), ‘Hicaznar’ (28,000) and a wide range of heat requirements for fruit ripening, i.e. ‘Suruc’ (73,670), ‘Katirbasi’ (74,105) and ‘Hicaznar’ (88,052) GDH. Under the Sanliurfa province conditions, two years average of effective heat summation requirement from bud swelling to 50 % flowering stage for ‘Suruc’, ‘Katirbasi’ and ‘Hicaznar’ cultivars are calculated as 643, 655 and 718 growing degree days (GDD) and from bud swelling to harvest are 2734, 2802 and 3289 GDD. It can be concluded that the effective heat summation of Sanliurfa province is enough for commercial growing for all pomegranate cultivars.     

梨每花序花朵数量与植物激素的关系

为探明影响梨每花序花朵数量的因素,调查了230个梨品种每花序花朵数量,简析了每花序平均花朵数量的梨品种数量频度分布。并从中选取每花序花朵数量极端差异的2个品种‘黄金’梨和‘金星’梨,采用液相串联质谱法(LC-MS)测定其花芽ZT、IAA、ABA含量,分析其每花芽分化花朵数量与植物激素的关系。结果表明:在常见梨品种中每花序有5~9朵花,‘黄金’梨的最多,平均为11.5朵,‘金星’梨的最少,平均为3.6朵。在花芽分化中后期,‘黄金’梨花芽的ZT含量极显著高于‘金星’梨;花芽分化过程中,‘金星’梨花芽IAA含量始终极显著高于‘黄金’梨;2个梨品种花芽ABA含量差异不显著。综上,花芽分化中后期花芽内高含量的细胞分裂素有利于促迚花朵的分化。     

Abscisic acid relationships in dormancy of apple buds

When potted, dormant, leafless seedling of ‘Antonovka’ apple were held for 15 weeks at 4 or 24°C, the patterns of change for abscisic acid (ABA) in buds were similar. At both temperatures, ABA concentration had decreased to a low level by 6 weeks and remained at a fairly low level until Week 12. The ABA concentration showed a tendency to rise in both treatments by Week 15.When excised axillary buds of ‘Northern Spy’ seedings were placed on 10^?4 M ABA medium immediately after excision, their growth was inhibited substantially depending on the length of exposure to ABA. When similar axillary buds were first allowed to begin growth on ABA-free medium, and then subsequently transferred to 10^?4 M ABA medium, no inhibition of growth occurred, even though these buds contained about twice as much ABA as did the buds placed directly on ABA medium prior to the beginning of growth.Thus, growing buds responded much less to exogenous applications of ABA than did non-growing buds. Diminishing of bud reaction to ABA responded to emergence from dormancy after 18 weeks of chilling.