稀土对刺槐苗木生理特性影响的研究

稀土对刺槐苗木生理特性影响的研究赵兰勇，梁玉堂（山东农业大学林学院泰安２７１０１８）王九龄（北京林业大学北京１０００８３）关键词稀土，刺槐，光合速率，叶绿素含量，水分利用效率，矿质元素含量近年来，稀土元素在农业上的应用研究越来越受到人们的重视，并且已...     

Footsteps from Insect Larvae Damage Leaf Surfaces and Initiate Rapid Responses

Plant resistance to insect herbivory involves gene expression in response to wounding and the detection of insect elicitors in oral secretions (Kessler and Baldwin, 2002, Ann. Rev. Plant/ Biol. 53: 299–328). However, crawling insect larvae stimulate the synthesis of 4-aminobutyrate within minutes and imprints of larval footsteps can be visualized within seconds through superoxide production or transient increases in chlorophyll fluorescence (Bown et al., 2002, Plant Physiol. 129: 1430–1434). Here cryo-scanning electron microscopy was used to demonstrate that larval feet, which are equipped with a perimeter row of hook-like crochets, damage leaf tissue and result in larval footprints. Staining for cell death shows that areas of wounding correspond to footsteps detected through increased chlorophyll fluorescence. Superoxide production in response to footsteps was inhibited by diphenyleneiodonium, an inhibitor of the plasma membrane NADPH oxidase enzyme. Inhibition of superoxide production, however, did not eliminate the detection of cell death. The results demonstrate that larval footsteps damage leaf tissue, and initiate rapid local responses which are not dependent on herbivory or oral secretions. It is proposed that superoxide production at the wound site prevents opportunistic pathogen infection.     

Growth- and leaf-temperature effects on photosynthesis of sweet orange seedlings infected with Xylella fastidiosa

The effects of growth and leaf temperature on photosynthesis were evaluated in sweet orange seedlings ( Citrus sinensis cv. Pera) infected with Xylella fastidiosa (the bacterium that causes citrus variegated chlorosis, CVC). Measurements of leaf gas exchange and chlorophyll  a fluorescence were taken at leaf temperatures of 25, 30, 35 and 40°C in healthy and infected (without visible symptoms) seedlings submitted to two temperature regimes (25/20 or 35/20°C, day/night), not simultaneously. The CO₂ assimilation rates ( A ) and stomatal conductance ( g _s) were higher in healthy plants in both temperature regimes. Values for A and g _s of infected and healthy plants were higher in the 35/20°C regime, decreasing with leaf temperature increase. In addition, differences between healthy and infected plants were higher at 35/20°C, while no differences in chlorophyll  a fluorescence parameters were observed except for potential quantum efficiency of photosystem II, which was higher in infected plants. Low A values in infected plants were caused by low g _s and probably by biochemical damage to photosynthesis. The high alternative electron sink of infected plants was another effect of reduced A . Both high growth and high leaf temperatures increased differences in A between healthy and infected plants. Therefore this feature may be partially responsible for lower growth and/or productivity of CVC-affected plants in regions with high air temperature.     

铜中毒对雏鸭某些血液指标的影响

选用1日龄天府肉鸭210只,随机分为3组,分别喂以对照日粮(Cu12.16mg/kg)、铜中毒日粮(Cu850mg/kg)和铜中毒日粮(Cu1050mg/kg)。试验期7周。以血液病理学方法观察了铜中毒对雏鸭某些血液学指标的影响。结果显示铜中毒组、组雏鸭分别于2周龄和3周龄开始出现临床症状,死亡18只和5只。血液病理学变化表现为,红细胞大小不等、变形变性、坏死溶解;红细胞数量和血红蛋白含量显著降低(P<0.01),血清谷丙转氨酶、谷草转氨酶活性显著升高(P<0.05或P<0.01),血清铜蓝蛋白活性下降。结果表明,铜中毒对雏鸭的生长发育和上述血液指标影响明显。     

Effect of water restriction on milk yield and quality in Lacaune breed ewes

The effect of water restriction on body weight, body condition score, milk yield, and milk composition and rheological characteristics in intensively reared Lacaune ewes was evaluated. After 7 days of adaptation, the trial lasted 28 days. Thirty lactating ewes (48 ± 5 months of age; mean value ± standard deviation) at the beginning of third lactation month were divided into three groups (n = 10), corresponding to the following water restriction treatment: a group control received no drinking water restriction (W100), and two groups received water to the extent of 80% and 60% of W100 daily consumption (W80 and W60 group respectively). The effects of water restriction were assessed at the beginning of experiment (D0), at D14 and D28. The W60 group resulted in a significant decrease in body weight, body condition score, milk yield and feed consumption of hay due to the experimental treatment; whereas a marked increase in both W60 and W80 groups of milk lactose, urea, sodium, sodium chloride content and titratable acidity was observed. Rheological parameters of milk, rennet coagulation time and curd‐firming time were positively affected by water restriction treatments, with a decrease in both experimental groups of the time required for the formation of a stable and firm curd. Results highlight the importance of water consumption in dairy sheep. The scarce availability of water, significantly affecting ewes milk production, is worthy of particular attention in arid area where water stress‐resistant breeds should be considered. This study underlines that milk yield, being closely linked to the availability of water of the breeding habitat due to its high water content (about 81%), could be reached in area where water is not a limiting factor without reducing the genetic expression of the animals. Less severe water restrictions, such as 20% of daily voluntary water intake, produce no detrimental effect on milk yield.     

X射线荧光光谱法快速测定稻谷中的镉

探索了一种对稻谷中重金属镉的快速、直接的测定方法,以适用稻谷集中收购、存储和流通过程中快速检测的的需要。样品无需前处理,直接磨成粉状即可上机测定。该方法采用X射线荧光光谱分析的原理,样品中的待测元素受激产生特征X射线,并由高性能探测器接收,得到镉元素的信号强度,然后根据信号强度与浓度的比例关系,经过软件处理自动计算样品中镉的含量,20min内完成精确定量。检出限可达到0.034mg/kg,实物标样标准偏差为0.016。此方法简单快速,并且准确性高,重现性好,可广泛应用于稻谷中镉的快速检测。     

穗期玉米昼夜生理状态规律的遥感综合探测研究

针对QY、PRI、NDVI、水势分别从不同的方面反映玉米的生理状况,以甜糯二号玉米作为材料,通过田间试验测量玉米昼夜4个参数值,研究了QY、PRI、NDVI、水势4个参数的昼夜变化,并且分析它们之间的相关性。结果表明,QY、水势、PRI三者具有很强的相关性,并且能建立回归模型表示它们之间的联系。     

Hyperspectral Models for Estimating SPAD Value of Cotton Leaves under Waterlogging Stress

[Object] To setup the hyperspectral sensing models for estimating SPAD value of cotton leaves under waterlogging stress. [Method] Irrigation and drainage controllable plots were introduced to simulate the waterlogging stress treatment in the flowering and boll forming stage, during which the change characteristics of the cotton leaf spectral reflectance and SPAD value were observed after 1 d, 3 d, 6 d, 9 d waterlogging, respectively. To find out the hyperspectral sensing models for estimating SPAD value of cotton leaves under waterlogging stress, the correlation and regression relationships between SPAD value and spectrum parameters were analyzed. [Result] (1) The SPAD value of the fourth cotton leaf from the top was significantly lower than control when suffers from waterlogging for 3 d, when waterlogged 9 d the SPAD value decreased by around 15% compared with the control. (2) The cotton suffering from waterlogged damage in the flowering and boll forming stage caused the reflection peak in green light wave band became steep, while the near infrared spectral reflectance increased, and caused the reduction of red absorption and red edge position "blue shifts", the red edge position drifts towards short wave with 4～5 nm when suffers from waterlogging for 9 d. With increase of the waterlogged days, the red edge slope and red edge area increased with a maximum value at 6 d of waterlogging, meanwhile, the skewness and kurtosis of red edge increased. (3) After waterlogging, the SPAD value of the fourth cotton leaf from the top (chlorophyll content) had a remarkable correlation with red edge slope(Dr), red edge position(λr), green peak reflection(Rg), green peak position(λg), red well position(λo), blue edge area(SDb), yellow edge skewness(Sy), yellow edge kurtosis(Ky), red edge skewness(Sr), red edge kurtosis(Kr), etc. An experience linear, polynomial and exponential models for estimating SPAD value had been built through using the Sy, Sr, Kr as independent variables, respectively, their determination coefficient (R²) were greater than 0.9, and the root mean square error (RMSE) were less than 1; and an experience binary linear regression equation for estimating SPAD value had been built through multivariate regression using the λg, SDr/SDb(VI3), Sb, Sy, Ky as independent variables, the R² was as high as 0.973, and the RMSE was 0.393. [Conclusion] The model can be remote sensing model used as estimating leaf SPAD of cotton value under waterlogging stress.     

浅析测定植物抗旱性方法的应用

本文介绍了干旱对植物伤害及表现,根据国内外相关文献资料对叶绿素荧光法和电阻抗图谱法两种测定植物抗旱性方法进行概述。     

1株解淀粉芽孢杆菌B7快速液态发酵优化工艺研究

本试验以1株饲用益生菌解淀粉芽孢杆菌B7（Bacillus amyloliquefaciens B7，B.amyloliquefaciens B7）为研究对象，为了增强其在液态条件下的发酵水平，提高其芽孢发酵工艺优化效率，拟采用测定芽孢吡啶二羧酸（dipicolonic acid，DPA）浓度的方法来代替传统的平板芽孢计数法，以探讨此测定方法在芽孢发酵优化工艺中的可行性。首先，通过单因素试验筛选出对菌株产孢有显著促进作用的因子，进一步通过正交优化试验确定蛋白胨、玉米粉、大米蛋白粉和Mn²⁺组合的最优水平。结果表明，发酵液中的芽孢浓度与测定的DPA荧光强度呈线性相关，在蛋白胨20 g/L、玉米粉10 g/L、大米蛋白粉20 g/L、Mn²⁺1.0 mmol/L时发酵48 h，检测到DPA荧光强度达到最大，其相应的芽孢浓度达到7.0×10⁹ CFU/mL。与实验室常用的LB培养基相比，芽孢浓度提高了3.3倍；与工业生产用培养基相比，芽孢浓度提高了2.2倍。本研究为芽孢杆菌发酵过程中芽孢浓度测定提供了一种快速方法，为工业菌株B.amyloliquefaciens B7的发酵提供了一种成分简单且高产芽孢的培养基。