牡丹嫁接成活率试验研究

进行牡丹嫁接成活率试验,结果表明:嫁接时间早、采用贴接法、选择适应强的品种、以牡丹根作砧木进行嫁接繁殖,在一定程度上能提高嫁接成活率。     

证券期望收益率同值变动时有效边界平移分析

先证明证券市场所有证券同值变动时，证券有效边界将上下平行移动，然后引入无差异曲线来说明市场中证券期望收益率同方向变化且变化值相差不大时，不必改变证券组合。     

Differential Response of Southern US Rice (Oryza sativa L.) Cultivars to Ultraviolet‐B Radiation

Elevated ultraviolet‐B (UV‐B; between 290 and 320 nm) radiation, because of depletion of the stratospheric ozone layer, is one of the major environmental factors influencing plant metabolic processes and yield. The southern US rice cultivars contribute greatly towards US rice production, but the effects of elevated UV‐B radiation on these cultivars are not well known. The objective of this study was to determine the effects of elevated UV‐B radiation on leaf photosynthetic rate (P_n), membrane stability, pollen viability, phenolic concentration and yield of eight commercially popular southern US rice cultivars (five inbred cultivars and three hybrids). Plants were grown in a temperature‐controlled greenhouse in Beaumont, TX, USA, and were exposed to UV‐B radiation of 0, 8 or 16 kJ m^?2 day^?1 for 90 days. For most of the cultivars, plants grown under 8 or 16 kJ UV‐B radiation showed significant decreases in P_n, membrane stability, pollen viability, and yield compared with the plants grown under an UV‐B‐free environment, whereas there was a significant increase in leaf phenolic concentration under 16 kJ UV‐B radiation. The hybrid ‘Clearfield XL729’ performed best among the selected southern US rice cultivars under 16 kJ UV‐B radiation.     

Relation of Seed Structures to Soybean Cultivar Difference in Pre-germination Flooding Tolerance

Abstract

Flooding during germination inhibits the sprouting and emergence of soybean [Glycine max (L.) Merr.], reducing subsequent growth and yield. Previous studies revealed that cultivars tolerant to pre-germination flooding have a mechanism of reducing water absorption speed (WAS) during the initial stage of inundation; however, seed structures involved in WAS have not been fully clarified to date. The objectives of this study were to identify possible seed structures responsible for cultivar difference in WAS and pre-germination flooding tolerance. WAS of two tolerant cultivars (Peking and Williams) and two susceptible cultivars (Nakasennari and Enrei), which were identified in our previous study, was compared in relation to seed structures. In Peking, WAS was markedly lower than that of the other cultivars, either in intact seed or seed with the seed coat removed, suggesting that both the seed coat and the embryo have a mechanism of reducing WAS in this cultivar. WAS of the hilum side tended to be higher than that of the back side, and sealing of the micropyle significantly lowered WAS, showing that the micropyle rather than the hilum appeared to be responsible for the higher WAS of the hilum side regardless of cultivar. A comparison of cross section area of the hilum revealed that the tolerant cultivars tended to have a larger area than the susceptible cultivars, suggesting that an inner space of the hilum can act as a reservoir at the initial stage of inundation, thereby reducing WAS in tolerant cultivars.     

Effect of thinning flower buds on fruit and seed traits and root yield of Panax ginseng C.A. Meyer

Panax ginseng C.A. Meyer, commonly known as ginseng, is a perennial herb. Agricultural practices have an influence on growth and yield of P. ginseng plants. Effect of thinning flower buds (treatment A (TA) the outermost whorl of flower buds in the umbels was retained while all other buds were excised; treatment B (TB) the two outer whorls of flower buds in the umbels) on fruit traits, which include number of fruits per plant, single fruit: double fruit ratio, fruit weigh (FW) per square meter, weight of 100 fruits, vertical length of fruit (VLF), horizontal diameter of the fruit (HFD) and thickness of the fruit (TF), seed traits, which include number of seeds per square meter, weight of 1000 seeds, number of different seed grading categories (extremely large seeds (ELS), large seeds (LS), medium-sized seeds (MS), small seeds (SS)) per square meter, vertical length of the seed (VLS), horizontal diameter of the seed (HSD), thickness of the seed (TS), and the root yield and total ginsenosides content of root of four- and five-year-old cultivated P. ginseng was studied in Fusong region of north-eastern China. The results showed that the FW and VLF, the weight of 1000 seeds, number of ELS per square meter, VLS and HDS of ELS, HDS and TS of MS and root yield were increased significantly by TA and TB (p < 0.05), whereas the number of MS and SS were significantly reduced (p < 0.05) in four- and five-year-old plants. The number of ELS and LS in TB and control were higher than that of in TA, and not significant was observed between TB and control. The root yield in TB was significantly higher than that in control of five-year-old plants. Number of the seeds per square meter of five-year-old plants was higher than that of four-year-old plants. The results indicated that the method of thinning flower buds, which was the two outer whorls of flower buds in the umbels, on five-year-old cultivated P. ginseng plants was a favourable method to promote the production of high-quality seeds and maximise the root yield.     

不同桉树在昆明市海口林场的早期生长研究

对昆明市海口林场2012年栽植的5种桉树早期生长性状进行了观测研究。结果发现，5种桉树中，造林成活率较高的有本沁桉、邓恩桉及多利桉，树高和地径表现最优的是多利按。不同种桉树中苗圃地生长表现最优的，上山栽植以后生长表现不一定最优，这与不同生长发育阶段、不同环境条件有着密切关系。     

杉木人工林南北坡向树高-胸径生长曲线研究

以SPSS为统计工具,将坡向分成南面坡和北面坡,对桃源县杉木人工林的胸径及树高曲线进行了拟合。Compound模型表明:同一胸径下,生长于南面坡的杉木,其树高和生长速度高于北坡;长势好的树木,具有更强的竞争力,生长速度更好。理论分析与实际情况相符,为杉木林的经营与管理提供了科学依据。     

Reliable data on fine-root turnover from sequential soil coring in an old carbon budget for a 14-year-old Scots pine from the late 1970s: Comments on Majdi et al., Scandinavian Journal of Forest Research 22: 299–303

Abstract

Comprehensive data from different research workers were included in the compilation of a carbon budget for a 14-year-old Scots pine (Pinus sylvestris) in the late 1970s, within the SWECON project (the Swedish Coniferous Forest Project). In a recent paper in the Scandinavian Journal of Forest Research, the authors published a surprisingly high turnover rate of fine roots (7.4 year^?1), maintaining that they had used our old SWECON data from our sequential soil coring. However, a close examination of our original data suggests a turnover of fine-root biomass of 2.3 and for fine-root standing crop (biomass+necromass) of 2.0 year^?1. Supporting evidence is available from other forest sites suggesting that our turnover rates were correctly estimated. Certain errors may exist in different parts of our old carbon budget, e.g. some measurements were carried out for different parts of the tree, while others were attributed to the whole stand. The sequential soil coring technique still remains the best technique available for fine-root growth and turnover estimates in forest stands.     

使用PMSG等激素提高四川黄牛繁殖效率研究再报

在初报基础上改进用药方法、扩大试验规模到２４头。发情率９５．８％，总受胎率７０．８％，得一胎孪生牛；校正后的产Ｄｕ间隔以对照组有显著缩短。该处理方法在缩短空怀期、治疗屡配不孕等方面表现了良好作用。重点讨论了该方法的适应范围、对动物选择的要求，以及处理后再发情时间与受孕效果的关系。     

壮禾增浸种培育壮秧机理研究

为探讨壮禾增浸种培育壮秧的生理机制，本文比较了用壮禾增浸种和用清水浸种对水稻种子生理特性、萌发和成苗等方面的差异以及这些差异在秧苗素质上的反映，分析了浸种时间对种子活力的影响。结果表明，用壮禾增浸种适宜时间可提高种子活力指数（ＳＶＩ）６．１％～１６．３％，田间播种成苗率提高５．３％，种子脱氢酶活性和淀粉活性显著增强，分别提高１２．４％和１３．２％，呼吸强度增加９．９％，种子生根出芽所需营养底物的供给得以加强，而且种子生活力的提高有助于秧苗的生长，秧苗根系发达，且抑制顶端优势，促进横向生长，分蘖发生早而快，叶片叶绿素含量高，光合物质积累多，秧苗综合素质提高。