量化修剪与喷施苹果面膜对果园经济效益的影响

为减少果园用工费,提高果园经济效益,在渭北旱塬以常规修剪苹果园为对照,监测量化修剪对疏花疏果用工费、果实品质和果园经济效益等的影响;在陕北丘陵沟壑区以苹果套袋（纸袋）为对照,监测喷施苹果面膜（腐殖酸型苹果免套袋膜剂）替代果实套袋对果园用工费、果实品质和果园经济效益等的影响。结果表明,量化修剪在冬季修剪时较常规修剪多支付用工费4500元/hm²,疏花可减少11250元/hm²,疏果可减少2250元/hm²;量化修剪的苹果单果重大,品质高,产值提高13.73%;经济效益提高34860元/hm²。喷施苹果面膜较果实套袋和去袋可减少用工费22850元/hm²,材料费减少8250元/hm²;喷施苹果面膜提高了苹果的外观商品价值和贮藏运输性能,产值提高50.01%;果园经济效益提高192900元/hm²。量化修剪和喷施苹果面膜降低了果园用工费,提高了果园经济效益,果园管理过程中应积极开展量化修剪和喷施苹果面膜。     

不同修剪和疏果措施对番石榴产量及果实品质的影响

修剪措施对番石榴新梢形成及产量提高效果显著,其中中梢修剪的新梢形成数量及产量最高。疏果措施即留单果、留双果对增加果实单果重、可溶性糖含量效果显著;对果实硬度、可滴定酸含量无明显效果;留单果对增加维生素C含量效果显著,留双果与对照没有显著差异。     

Biomass allocation and nodulation of Gliricidia sepium under two cut-and-carry forage production regimes

The effects of two pruning regimes on the above-ground biomass allocation and nodulation of Gliricidia sepium (Jacq.) Walp. (Leguminosae: Robinieae) were studied in a cut-and-carry forage production system under humid tropical conditions in Guadeloupe, French Antilles. The grass layer composed of a mixture dominated by Paspalum notatum Flügge (80%) and Digitaria decumbens Stent. The pruning regimes were partial pruning (ca. 50%) every two months and complete pruning every six months. The complete pruning caused an almost complete turnover of N2 fixing nodules. The nodule biomass decreased after the partial pruning, but the turnover was not complete. The nodule to foliage biomass ratio followed the same pattern under both treatments, and the values of the ratio converged towards the end of the experimental period. The maxima of standing nodule biomass were 7.2 and 13.0 kg ha−1 in the partially and completely pruned trees, respectively. The cumulative leaf fodder harvest was higher under partial pruning management, due to smaller litter loss. The branch biomass production was higher under complete pruning management. Grass production was not affected by the pruning pattern of G. sepium. It was concluded that the partial pruning management produces more fodder in the studied association, and the nodulation probably adjusts to the canopy N requirements. The potential N release to soil in the turnover of nodules of G. sepium (max. 0.82 kg ha−1) is negligible compared to the N export in tree and grass fodder harvest, 190 and 215 kg ha−1 in partially and completely pruned plots, respectively. This revised version was published online in June 2006 with corrections to the Cover Date.     

Effects of green pruning on growth and stem shape of Eucalyptus nitens (Deane and Maiden) Maiden

An experiment was established in two high quality Eucalyptus nitens Deane and Maiden (Maiden) plantations in Tasmania. At the start of the experiment the trees were three years old and the plantations were on the point of canopy closure. Selected trees were pruned to remove 0, 50% or 70% of the lower green crown length, and each was surrounded by eight unpruned trees. The 50% treatment had no impact on height or diameter increment in the two years following treatment, but removal of 70% of the lower crown length resulted in significant decreases in both height and diameter increment. There were no changes in the height of 50%-pruned trees relative to the height of surrounding unpruned trees (relative height), and it was concluded that dominance would not be affected by this treatment. The relative height of 70%-pruned trees was less at one site, and this treatment may result in loss of dominance. Stem taper was generally unaffected by either pruning treatment. Changes in stem form were restricted to trees in the 70% pruning treatment and were only transient. It was concluded that removal of 50% of the lower green crown length is an appropriate level of pruning for the species provided that growth rates are rapid and pruning is timed to coincide with canopy closure. Since dominance was unaffected by this level of pruning, thinning at the time of pruning is unnecessary. It may be possible to minimise the impact on growth of higher levels of pruning by thinning at the time of pruning.     

Field performance of containerized black spruce seedlings with root systems damaged by freezing or pruning

Roots of 2-year-old black spruce seedlings (Picea mariana [Mill.] B.S.P.) were exposed to freezing temperatures to destroy 20, 40, 60, and 80% of the root systems. For comparison, other root systems were pruned to eliminate the same proportions of roots. Treated and control seedlings were planted in spring 1992 at Forêt Montmorency (the Université Laval forest research station, 50 km north of Quebec City). From 1992 to 1995, survival, shoot height and stem diameter were measured. Mortality mainly occurred in 1993, the year after planting; pruned seedlings showed practically no mortality while seedlings with 20, 40, 60, and 80% of their root systems affected by frost showed mortality rates of 0, 6, 17, and 24%, respectively. Shoot height and stem diameter decreased with increasing root damage when compared to controls. After three years on the planting site, shoot height was reduced by 2, 8, 11, and 18% while stem diameter was reduced by 4, 21, 25, and 24% for 20, 40, 60, and 80% frost damage, respectively. For pruned seedlings, shoot height was increased by 3% at 20% damage and was decreased by 1, 3, and 13% for 40, 60, and 80% root damage while stem diameter was reduced by 1, 4, 8, 19% for 20, 40, 60, and 80% respectively. Use of damaged seedlings on the planting sites should be limited in order to reduce the cost of replacement planting.     

疏伐及修剪对油松无性系开花和树体的影响

在对兴城油松种子园的去劣疏伐、截顶和修剪基础上,就几种技术措施对无性系植株花量、枝条生长的影响和控制树高的有效性作了调查分析．去劣疏伐后第３年保留株的雌花量增长显著,枝均雌花量为对照的１．５～２．７倍,树冠下部枝条花量的增长较大;截顶、疏枝修剪均能显著提高雌球花量,对２０龄左右植株的促花效果要好于１０龄左右植株,且效果持续时间长;截顶＋修剪处理对树冠上部枝条雌花量的促进作用高于对下层枝条;无论是去劣疏伐还是截顶修剪,其保留植株的雄球花量均低于对照;截去１９龄植株顶端５年生主干能够控制株高,截去１２龄植株顶端３年生主干后有“多头”和侧枝替代主干趋势,１２龄植株在截顶后胸径生长有明显下降现象．对不同嫁接年龄无性系植株截顶疏枝的处理效果,疏伐和截顶疏枝对雌、雄球花影响的差异等问题作了探讨．     

Leucaena hedgerow intercropping and cattle manure application in the Ethiopian highlands II. Maize yields and nutrient uptake

 The effects of Leucaena leucocephala and L. pallida prunings and cattle manure on maize nutrient uptake and yield were investigated in a hedgerow intercropping trial in the Ethiopian highlands. Hedgerow intercropping (also called alley cropping) is an agroforestry system in which trees are grown in dense hedges between alleys where short-cycle crops are grown. The hedges are pruned periodically during the cropping period and the prunings are added to the soil as green manure. For each leucaena species, the experiment had 16 treatments resulting from a factorial combination of four levels of leucaena leaf prunings (no prunings applied; first prunings applied; first and second prunings applied; first, second and third prunings applied), two levels of air-dried cattle manure (0 and 3 t dry matter ha^–1) and two levels of N fertilizer (0 and 40 kg N ha^–1 as urea). Uptake of N, P and K increased significantly with application of the three nutrient sources, but uptake of Ca and Mg either did not respond or decreased with application of prunings and manure. All the three factors increased maize grain and stover yields significantly, usually with no significant interactions between the factors. At least two applications of prunings were required to significantly increase nutrient uptake and maize yield. Maize in the row closest to the hedge did not respond to these nutrient inputs. It is concluded that hedgerow intercropping, with or without manure application, can increase crop yields moderately (to 2–3 t ha^–1 maize grain yields) in the highlands, but P, Ca and Mg may have to be supplied from external sources if they are deficient in the soil. Additional N is still required for higher yields (>4 t ha^–1 maize grain yields). However, quantification of the competition effects of the trees is also required to confirm these results. Received: 27 January 1997     

白肋烟打顶技术探讨

通过对白肋烟的烟叶经济性状、烟株株型、烟叶成熟度及烟叶化学成分的比较分析认为,开花始期打顶的烟株,上下部叶片长势成熟均匀,烟叶成熟适宜,内在化学成分协调,因此,开花始期是最适宜的打顶期;留叶２０片左右烟叶化学成分协调,产量、产值高,是适宜的留叶数;打顶位置以倒数第４片叶和第５片叶之间为宜,留叶部位以此下数至适宜留叶数．     

生长季修剪对库尔勒香梨生长的影响

库尔勒香梨3年生幼树在5月12日、6月8日、7月6日三个时期进行生长季修剪能够开张枝条角度,降低树冠高度,扩大树冠,缓和树势,促进花芽分化,以7月6日进行修剪效果最好,发育枝生长量、背上枝生长量最短,干径和花芽量最大都达到显著水平,为早期丰产奠定基础。     

枣树修剪枝条弯曲及压缩特性研究

为解决密植枣园枝条粉碎还田机粉碎装置设计和枣树修剪枝条数值化建模缺乏部分关键力学参数和理论基础的问题,以十四师224团枣树修剪枝条为研究对象,采用8801型万能试验机进行了弯曲和压缩试验.设计了三因素五水平正交试验,研究了标距跨度、加载速度、取样部位对枣树修剪枝条弯曲性能的影响;设计了单因素试验,研究了压缩速度、压缩方...