Effects of light,macronutrients, and sucrose on germination and development of the endangered fern Adiantum reniforme var. sinense (Adiantaceae)

Effects of light, macronutrients strength of Murashige and Skoog (MS) (1962), and sucrose in the culture medium on spore germination and gametophyte development of the endangered fern Adiantum reniforme var. sinense were investigated. The presence of light was found to be essential for both spore germination and gametophyte growth. Moreover, a medium consisting of 1/4 MS with 15 g/l sucrose was optimal for spore germination and early gametophyte development; whereas, MS medium with 30 g/l sucrose was optimal for further gametophyte development. Increasing amounts of sucrose (45–60 g/l) in the medium delayed gametophyte growth and development. Additionally, sporophyte formation and early growth of gametophytes in a medium consisting of clay and peat (v/v = 1:2) was higher than those in a medium consisting of pure river sand. These findings indicated that requirements for nutrients for spore germination and early gametophyte development of A. reniforme var. sinese were relatively low, but these increased with further gametophyte development, formation and growth of sporophytes.     

基于GA-BP网络的西藏高海拔地区ET0预报

选择那曲县(海拔4 450 m)、改则县(海拔4 700 m)作为西藏高原气候典型地区,通过遗传-神经(GA-BP)网络训练,应用1983—2012年30年的数据建立GA-BP网络模型,采用前一年的气象资料预报当年的参考作物腾发量,当2010—2012年连续3年的预报值均满足设定的阈值下限时,输出预测结果,这样使得模型在保证了预报精确度的同时兼具预报稳定性。结果发现:经GA-BP网络确定的2010—2012年3年模型预报值与真实值间的线性关系明显,决定系数R~2分别达到0.8805、0.9363、0.9167,斜率接近于1;多年的模拟预报值与实际值之间的相对误差均处于0.1以下,小于设定的阈值下限。对于易获得气象资料的地区,研究成果可对高海拔地区未来月际间作物需水量的变化进行预判,进而为将来灌溉制度的制定提供依据;对于缺测气象资料的地区,通过本文建立的网络模型,结合气象条件类似的站点,可在大时间尺度下对该地区ET_0变化趋势进行模拟,同时对下年度灌溉制度的拟定提供指导。     

Changes in carbohydrate and nitrogenous components and amylase activities during germination of grain amaranth

Grain amaranth (Amaranthus hypochondriacus), Yercaud local variety, was soaked overnight and germinated for 192 h taking the soaked grains as the zero time (0 h) sample. The changes in the activities of - and -amylases, starch, sugar, protein and lysine contents during germination are reported. Activity of -amylase was high in the 0 h soaked grains, while -amylase activity was high in 72 h germinated grains. The joint action of the amylases resulted in a decrease of starch content from 0 to 192 h in germinated grains and an increase in total sugars during the initial period of germination.Protein nitrogen was found to decrease from 48 h to 192 h accompanied by an increase in free amino acid and non-protein nitrogen contents. Total lysine content was found to be increased by 31% in 24 h germinated grain amaranth. Protein fractionation of raw, soaked and 24 h germinated grain amaranth showed that the distribution of different types of proteins varied during germination of the grains. An increase of water soluble protein content was noticed in 24 h germinated grains.     

Comments on the importance of green vegetables

Green, especially leafy, vegetables are widely underesteemed because few horiticultural research institutes publish figures demonstrating that they can give unusually large annual yields of edible dry matter, including protein and carotene (provitamin A). It is also not realised that they supply many communities with as much protein as is supplied by fish, and that more communities used to eat them on that scale. Before leafy vegetables gain proper nutritional attention it will be necessary to convince consumers that they are not merely sources of vitamin C and minerals, or decorative adjuncts to a meal. It will also be necessary to persuade those who compile dietary and production statistics to separate leafy vegetables from other horticultural products which, although they may yield more profit per hectare, are of much less nutritive value.     

Lucerne shoot and root traits associated with adaptation to favourable or drought-stress environments and to contrasting soil types

Cultivar × location interaction for lucerne forage yield across northern Italy is large, repeatable and associated with summer drought-stress level and soil type. The objectives of this study were: (i) to investigate the genotypic factors associated with cultivar adaptive responses to drought-stress and soil factors; (ii) to identify adaptive traits exploitable for selection of widely adapted or specifically adapted material. Aerial dry matter (DM) over 12 harvests and shoot traits of 13 landraces and four varieties were evaluated in four artificial environments created by the factorial combination of drought-stress level (almost nil or high) and soil type (sandy-loam or silty-clay) (Exp. 1). Aerial and root DM over four or five harvests were evaluated in metal containers 55 cm × 12 cm × 75 cm deep for the factorial combinations of three varieties by two drought-stress levels by two soil types (Exp. 2), or six landraces by two drought-stress levels (Exp. 3). Cultivar × environment interaction was detected for forage yield, plant mortality after the second summer, leaflet size and stem weight. The environments of Exp. 1 reproduced well the variety adaptive responses across agricultural environments. The relationship of cultivar forage yield with shoot traits was environment-specific, i.e.: (i) strictly negative with plant mortality, in no-stress environments (where mortality and plant competition were severe); (ii) positive with stem number per plant and autumn-winter growth, in stress environments; (iii) positive with stem dry weight, in ‘stress/sandy-loam soil’; and (iv) positive with leaflet size, in ‘no-stress/sandy-loam soil’. Cultivars specifically adapted to no-stress or sandy-loam conditions showed consistently greater root DM across three soil layers than material with opposite adaptive response. Entry yields tended to inverse genetic correlation between two environments which represented contrasting geographical subregions and were characterized by different combinations of traits associated with higher yield, i.e.: (i) higher root biomass, lower plant mortality and larger leaflets, for ‘no-stress/sandy-loam soil’; and (ii) more stems per plant and greater autumn-winter growth, for ‘stress/silty-clay soil’. The difficulty of yield-based selection for wide adaptation may hardly be overcome by selection based on adaptive traits. Adaptive trait-based selection for specific adaptation may be envisaged especially for ‘stress/silty-clay soil’ conditions, for which the relevant traits are inexpensive to record, not correlated, and not subject to cultivar × environment interaction.     

On determination of chitin content in mushrooms

Nitrogen compounds constitute the greatest proportion of the dry weight of mushrooms. These nitrogen compounds are partly protein and partly non-protein. A modified Heneberg-Stohman's method was used to separate non-protein from protein nitrogen, as well as to determine raw fiber content in mushrooms, since the methods used previously for this purpose are time-consuming and complicated. Elemental analysis of crude fiber was performed to confirm the uniformity of isolated products. The content of total crude fiber (fungin) and the proportion of chitin and cellulose in it were determined. The chitin content of 15 species of field grown edible mushrooms was in the range of 1.87–6.93% of total dry mass and 34.51–67.72% of isolated fungin.     

Microwave l-band (1730 MHz) accurately estimates the relative water content in poplar leaves. A comparison with a near infrared water index (R1300/R1450)

In this study the estimation of reflectivity at 1730 MHz (l-band), measured with a microwave digital cordless telephony (DCT) patch antenna, is presented as an easy-to-handle and non-destructive new method to assess the relative water content (RWC) of poplar leaves and filter discs at different levels of dehydration. The accuracy of this new method has been contrasted with the R₁₃₀₀/R₁₄₅₀ index, determined by a portable near infrared (NIR) spectrometer. The close correlations found between RWC and the reflectivity at a frequency of 1730 MHz, both for filters and leaves, indicate that microwave determinations are rather independent of the physical properties of the material analysed. On the contrary, the differences found between poplar leaves and leaf filters in the relationships established between RWC and the R₁₃₀₀/R₁₄₅₀ index demonstrate a strong influence of the properties of the material in NIR reflectance measurements, specifically as they relate to changes in leaf thickness during dehydration. It should be noted that the amount of energy received by the leaf for the microwave technique (0.1 mW) was much lower than that received for the measuring of the R₁₃₀₀/R₁₄₅₀ index (2.5 W). Moreover, R-square coefficients were higher for microwaves than for the R₁₃₀₀/R₁₄₅₀ index. The use of a technologically simple, low cost and portable device, based on a microwave DCT patch antenna, could yield a solid support for the development of a commercial apparatus enabling the determination of plant water status under field conditions.     

丝核菌分离方法的研究

本文利用0,10~(-3),10~(-4),10~(-5),10~(-6)和10~(-7)不同浓度的敌克松水溶液浸泡干燥的甜荞茎杆后,再用茎定殖法从8个自然感染丝核菌的土壤中和一个人工混有丝核菌的土壤中,以及1个人工混有丝核菌和其它真菌的土壤中,分离丝核菌。结果表明,采用修订茎定殖法,即用10~(-5)浓度的敌克松水溶液浸泡后的甜荞茎分离丝核菌,在提高丝核菌的分离率和降低杂菌的污染率方面都明显的优于其它处理。此方法可用于丝核菌的分离和土壤中丝核菌数量动态的定量研究。     

一类时滞系统的解半群的范数连续性

讨论了时滞线性系统的解半群的范数连续性,其方法是:在一个特定的相空间中,把时滞系统转化为无时滞的抽象柯西问题,再运用半群理论解决解半群的范数连续性.     

农牧交错带荒漠化程度土壤评判指标的确定

以陕北农牧交错带的荒漠化土壤为研究对象,通过多元相关分析、回归分析和因子分析,确定了荒漠化程度的土壤评判指标。结果表明,评判土地荒漠化程度时,土壤物理性质指标应选择0.25~0.05 mm砂粒含量,土壤化学性质指标应选择土壤有机质含量,并运用这两个指标建立了荒漠化程度土壤评判指标体系,即通过荒漠化土壤表层0~20 cm上述两个指标的量值来评判荒漠化程度。