部分月季花品种的数量分类研究

用数量分析的方法,对80个月季、蔷薇及其远缘杂种的样本进行了系统分析与整理。Q型聚类分析结果表明,可将80个样本分为9类,并初步揭示了各类型间的亲缘关系。首次提出了将中国古老月季分为高大和低矮两个型,将新培育出的具有较高抗性的远缘杂种月季另立为灌丛月季型的分类方案。同时,分析并预测了采用中国原产的蔷薇野生种与古老月季品种或现代月季品种杂交,后代可能形成的月季品种类型。并对花卉品种数量分类中的一些方法进行了初步探讨。     

Seasonal uptake of 15N-nitrate and distribution of absorbed nitrogen in peach trees

The absorption and distribution of N was measured monthly throught a calendar year in 3-year old peach trees (Prunus persica (L) c.v. Maycrest) grafted on Nemaguard rootstock. Plants were grown on siliceous sand in 500-L pots and fertilized with a solution containing ¹⁵N enriched KNO₃. During flowering and fruit set (March) approximately 7% of N found in new growth came from the fertilizer and the remainder came from the N stored in the old organs. Maximum N absorption took place during the periods of fruit ripening and maximal vegetative growth (May to August). This nitrogen was relocated from leaves to woody tissues and stored as reserve-N before leaf fall. In the following growth season reserve-N was used for flower development and new shoot growth. The N absorbed during plant dormancy was quite low and remained in the stem bark and roots mainly as soluble-N.     

Maximum axial root growth pressure in pea seedlings: effects of measurement techniques and cultivars

Values of the maximum axial growth pressure (σ_max) of seedling pea (Pisum sativum L.) roots reported in the literature, obtained using different apparatuses and cultivars, range from 0.3 MPa to 1.3 MPa. To investigate possible reasons for this large range, we studied the effect of apparatus and cultivar on measurements of σ_max in peas. We describe four types of apparatus which can be used to measure axial root growth force and hence σ_max, and used them to measure σ_max in seedling pea roots using cultivar Meteor. Two of these apparatuses were also used to compare σ_max for three pea cultivars (Helka, Meteor and Greenfeast). Both cultivar and apparatus significantly affected σ_max , but there were greater differences between apparatuses than between the three cultivars. Estimating root cross-sectional area from the diameter of cross-sections, rather than from in situ measurements (i.e. measurements made with the root still in place in the apparatus) may explain these differences. This revised version was published online in June 2006 with corrections to the Cover Date.     

Management of disease resistance diversity of cultivars of a species in single fields: controlling epidemics

The use of a diversity of resistance genes limits the development of polycyclic epidemics caused by airborne pathogens and reduces the risk that resistance be overcome by virulent races. Diversity can be easily achieved by growing mixtures of cultivars with different resistance genes and homogeneous agronomic traits. The mechanisms by which disease is reduced in cultivar mixtures include the loss of inoculum due to the presence of resistant plants between susceptible ones and resistance induced by avirulent pathogens. The complementary effects of individual mixture components reacting to disease pressure and to abiotic stresses result in greater yield stability compared with pure stands. The quality of products from mixtures is at least equal to that obtained with pure stands. This type of resistance management is applicable to both annual and perennial crops.     

Susceptibility of Soybean Cultivars and Lines to Pratylenchus hexincisus

Population increase of Pratylenchus hexincisus on 41 soybean cultivars (maturity groups I-VI) and lines was tested under greenhouse conditions. After 3 months, P. hexincisus was recovered from the roots of all plants tesled. Final populations of P. hexincisus per pot were larger than the initial population in 13 cultivars. Pathogenicity of P. hexincisus on five soybean cultivars representing maturity groups (I-V) was demonstrated under greenhouse conditions. An inoculmn of 5,000 P. hexineisus/plant significantly decreased the root and shoot biomass of all five soybean cultivars after 3 months.     

Increasing global agricultural production by reducing ozone damages via methane emission controls and ozone‐resistant cultivar selection

Meeting the projected 50% increase in global grain demand by 2030 without further environmental degradation poses a major challenge for agricultural production. Because surface ozone (O₃) has a significant negative impact on crop yields, one way to increase future production is to reduce O₃‐induced agricultural losses. We present two strategies whereby O₃ damage to crops may be reduced. We first examine the potential benefits of an O₃ mitigation strategy motivated by climate change goals: gradual emission reductions of methane (CH₄), an important greenhouse gas and tropospheric O₃ precursor that has not yet been targeted for O₃ pollution abatement. Our second strategy focuses on adapting crops to O₃ exposure by selecting cultivars with demonstrated O₃ resistance. We find that the CH₄ reductions considered would increase global production of soybean, maize, and wheat by 23–102 Mt in 2030 – the equivalent of a ~2–8% increase in year 2000 production worth $3.5–15 billion worldwide (USD₂₀₀₀), increasing the cost effectiveness of this CH₄ mitigation policy. Choosing crop varieties with O₃ resistance (relative to median‐sensitivity cultivars) could improve global agricultural production in 2030 by over 140 Mt, the equivalent of a 12% increase in 2000 production worth ~$22 billion. Benefits are dominated by improvements for wheat in South Asia, where O₃‐induced crop losses would otherwise be severe. Combining the two strategies generates benefits that are less than fully additive, given the nature of O₃ effects on crops. Our results demonstrate the significant potential to sustainably improve global agricultural production by decreasing O₃‐induced reductions in crop yields.     

Management of the late blight (Phytophthora infestans) disease of potato in the southern hills of India

Late blight of potato is considered to be the most devastating problem causing severe yield losses in potato worldwide. Among the different management strategies, the use of resistant cultivars is the most viable option, but the non‐availability of enough quantity of quality seed materials of resistant cultivars forces the farmers to grow susceptible cultivars with proper fungicide scheduling. Therefore, in the present study, chemical control using fungicide has been attempted with newer molecules in the susceptible cultivar along with a resistant cultivar as a positive control. All the tested fungicides were found safe, and no phytotoxicity was observed with any chemical at the applied rate. In resistant cultivar, no late blight was appeared in both the years, whereas maximum AUDPC was observed in the untreated control (276.3) and minimum (41.7) in mancozeb‐cymoxanil + mancozeb based scheduling which was found on par with chlorothalonil‐famoxadone + cymoxanil (51.3) and chlorothalonil‐ametoctradin + dimethomorph (53.5) based scheduling. Among the treatments, resistant cultivar, Kufri Girdhari followed by chlorothalonil‐ametoctradin + dimethomorph and mancozeb‐cymoxanil + mancozeb based fungicidal scheduling were proven as the best treatments for both the crop seasons resulting in the highest yield parameters. The disease severity showed a strong negative correlation with the tuber yield of potatoes in both the years. Based on overall observations including BC ratio, it can be concluded that, wherever seed material of resistant cultivar is available farmers should grow the same or else with susceptible cultivars the fungicidal scheduling based on mancozeb‐cymoxanil + mancozeb or chlorothalonil‐ametoctradin + dimethomorph can be followed to obtain the maximum returns with effective management of late blight at the southern hills of India.     

梨品种资源果实轮纹病抗性的评价

采用田间人工接种的方法,2009-2010年连续两年对保存于国家梨种质资源更新圃的182个品种进行果实轮纹病抗性评价。结果表明：砂梨、白梨、秋子梨、种间杂交梨、西洋梨和新疆梨的两年平均发病率分别为6.15%、7.20%、7.43%、12.66%、17.00%、18.93%,梨品种间对轮纹病抗性存在差异,不同条件下多数品种轮纹病发病率有差异。依据两年平均发病率进行抗性评价分级,72个品种为高抗、63个品种为抗、25个品种为中抗、14个品种为低抗、8个品种为不抗。     

The GmCLC1 protein from soybean functions as a chloride ion transporter

Soil salinization is a global issue that hampers agricultural production. Chloride is one of the prominent anions on saline land that cause toxicity to the plant. We previously identified the GmCLC1 gene from soybean (Glycine max) that encodes a putative tonoplast-localized chloride transporter. In this study, using electrophysiological analysis, we demonstrated the chloride transport function of GmCLC1. Interestingly, this chloride transport activity is pH dependent, suggesting that GmCLC1 is probably a chloride/proton antiporter. When the cDNA of GmCLC1 was expressed in tobacco BY-2 cells under the control of a constitutive promoter, the protective effect against salinity stress in transgenic tobacco BY-2 cells was also found to be pH sensitive. In the native host soybean, the expression of GmCLC1 gene is regulated by pH. All these findings support the notion that the function of GmCLC1 is regulated by pH.     

Unexpected hybridization reveals the utility of genetics in native plant restoration

Native plant materials (NPMs) are increasingly utilized during the restoration of disturbed plant communities. Here, we analyze next‐generation genetic sequencing data for Hilaria jamesii, a dominant graminoid across drylands of the southwestern United States, and document that the species' only commercially‐available NPM, “Viva,” is a hybrid between H. jamesii and its sister species, Hilaria mutica. In fact, hybrids between these species are common where they geographically overlap. Furthermore, we show that the “Viva” hybrid has successfully been moved beyond the hybrid zone and into the core range of H. jamesii. The potential ramifications of introducing novel genetic material into H. jamesii are discussed, as well as the utility of genetic analyses to protect species' natural patterns of genetic diversity and help managers make informed decisions regarding the development and deployment of NPMs.