树势平衡在果树修剪中的分析

在修剪果树的时候要秉承“强分散,弱集中”的原则,参考不同采树的内部和外部条件进行挑战,才能确保果树处于一个中庸,产量高的树势水平,同时对于果树的优质、稳产、高产都起着十分重要的作用。为此本文就怎样判断技势,树势的强弱和平衡的问题,简述了一些看法。

高光效树形在果树上的应用探讨

目前,高光效树形已经在果树种植中得到了广泛应用。因此,对高光效树形在果树中的应用进行了详细分析,以期为相关单位的种植提供参考和借鉴。

Effects of Regulated Deficit Irrigation on Twig Water Potential of Korla Fragrant Pear

With 7-year-old Korla fragrant pear trees as the experimental material, different root-zone irrigation patterns were arranged to study the effects of soil moisture on twig water potential of Korla fragrant pear trees at different growth stages. The results showed that under the condition of regulated deficit irrigation, the diurnal dynamics of twig water potential of Korla fragrant pear trees was V shaped at different growth stages, and the twig water potential of Korla fragrant pear trees reached the minimum during 14：00-16：00. At different growth stages, the twig water potential of Korla fragrant pear trees under drought stress was significantly lower than that of pear trees irrigated normally. Under both drought stress and normal irrigation, the diurnal variation of twig water potential of Korla fragrant pear trees during the flowering period was most gentle, that during the fruit-setting and mature periods showed some ups and downs, and that during the fruit enlargement period was greater. Under the experimental conditions, the twig water potential of Korla fragrant pear trees was positively correlated with soil moisture content, and the functional relationships between them at different growth stages were studied by regression analysis. In addition, the limits of twig water potential and soil moisture content for normal growth of Korla fragrant pear trees at different growth stages were determined.

EFFECT OF HOST PLANTS AND INOCULUM FORMS ON THE INOCULUM POTENTIAL OF ARBUSCULAR MYCORRHIZAL FUNGI

The effects of inoculum forms (single-spore, multi-spores, or colonized root pieces) and host plants (Nicotiana tabacum L., Sorghum sudanense (Piper) Stapf, and Trifolium repens L.) on the development and inoculum potential (IP) of the arbuscular mycorrhizal fungi (AMF) :Glo-mus macrocarpum Tul & Tul, donuis mosseae (Nicol & Gerd.) Gerdemann & Trappe, Glomus ver-siforme (Karsten) Berch, and Sclerocystis sinu/osa Gerdemann & Bakhi cultured in pots were investigated. The lag phase of treatment with 50 spores or 0.5 g (fresh weight) of colonized root pieces was 4 weeks, much shorter than that of the treatment with 1 spore (8 weeks); the value of IP (VIP) and percentage of root colonization (PRC) of the former were greater than those of the latter. Only on the early stages of colonization was there difference between the 50 spores and the 0.5 g (fresh weight) of colonized root piece inoculation treatments. The EP per plant inoculated with 0.5 g (fresh weight) of colonized root pieces of AMF was greater than that of the other two treatments except G. versiforme on Nicotiana tabacum, while the PRC of the plants inoculated with 50 spores and 0.5 g (fresh weight) of colonized root pieces of AMF was higher than that of the 1 spore inoculation after 10 weeks. Trie VIP of AMF on Trifolium repens was significantly higher than that on the other two hosts. The VIP of G. mosseae, G. versiforme, and S. sinuosa was respectively greater than that of G. macrocarpum. This suggested that different species of AMF produced different VIP of the inoculum . Nicotiana tabacum was much better than the other host plants which used to be inoculated with single spore, and to produce inocula of AMF.

猕猴桃树冬剪要点

冬剪是为了整形、增加树体通风透光性,以利于来年提质稳产。修剪时,要掌握好以下几点:1.枝势一致。修剪时,枝条粗细要尽可能接近,不能粗细悬殊过大。保持枝势一致是萌芽一致、开花一致、坐果一致的基础。结果母枝的选留,按“多芽少枝”的修剪标准,留的结果母枝以中庸枝为主。中庸枝一般是基部直径在1~1.5厘米、枝势健壮、木质化程度高、芽体饱满充实的枝条。2.数量匹配。

Effect of UV-B irradiation on interspecific competition between Ulva pertusa and Grateloupia filicina

We report the effect of UVoB irradiation （9.6 kJ m-2 day^-） on interspecific competition between two species of macroalgae, Ulva pertusa （U） and Grateloupiafilicina （G）, in co-culture. Growth of U. pertusa and G. filicina was inhibited by UV-B irradiation in mono-culture and specific growth rate （μ） declined as a result. Interspecific competition between U. pertusa and G filicina was closely related to the initial weights when co-cultured. When initial ratios of U. pertusa （U） to G filicina （G） were U：G=I.2：I and 1：1, U. pertusa was the dominant algae. When the initial U：G ratio was 1：1.2, G. filicina was competitively dominant in the earlier stage, but U. pertusa grew faster, superseding G. filicina in the later stage. At initial ration U：G = 1：1.4, G. filicina was predominant. Under UV-B irradiation, the competitive ability of G filicina was weakened and the interspecific competitive balance favored U. pertusa, which suggests that G. filicina was more sensitive to UV-B irradiation. We also probed the potential allelopathic effects between the two species, which led to mutual growth inhibition.

Arbuscular mycorrhizal fungi enhance the growth of the exotic species Ambrosia artemisiifolia

Arbuscular mycorrhizal fungi(AMF)can increase host plant nutrient uptake via their mycelium,thus promoting plant growth.AMF have always been associated with successful invasion of most exotic plant species.However,knowledge regarding how AMF affect the success of plant invasion remains limited.Exotic Ambrosia artemisiifolia is an invasive and mycorrhizal plant species.A long-term field experiment was conducted to examine the differences in AMF diversity and composition in the roots of A.artemisiifolia and Setaria viridis subjected to interspecific competition during growth.A greenhouse experiment was also performed to test the effect of Funneliformis mosseae on the growth of these two species.Ambrosia artemisiifolia invasion caused AMF diversity to change in native S.viridis roots.Meanwhile,the relative abundance of F.mosseae was significantly higher in the roots of A.artemisiifolia than in those of S.viridis.The higher AMF colonization rate in the exotic species(A.artemisiifolia)than in the native species(S.viridis)was found in both the field and greenhouse experiments.The greenhouse experiment possibly provided that AMF advantaged to the growth of A.artemisiifolia,by influencing its photosynthetic capacity as well as its phosphorus and potassium absorption.These observations highlight the important relationship of AMF with the successful invasion of A.artemisiifolia.