白洋淀湖泊湿地中氮素分布的初步研究

湿地中氮素的空间分布在一定程度上反映了湿地环境变化的进程。对白洋淀3个典型淀区沉积物、孔隙水和上覆水中有机质和氮素进行分析,结果表明,白洋淀湖泊湿地沉积物中的有机质和全氮含量在垂直分布上表现出较好的一致性,均随深度增加而减少;但有机质和全氮分布存在空间差异性,英家淀的有机质和全氮含量均高于小杨家淀和小鸭淀;沉积物在6 cm深处,小杨家淀和小鸭淀沉积物中全氮出现一次低值,而所有采样点孔隙水中NH4 -N浓度都在此处出现一个峰值,表明6 cm深度可能是白洋淀湖泊湿地微生物降解有机氮的一个活跃区;芦苇湿地上覆水中NH4 -N和NO3--N含量都高于宽阔湖面水体,说明植被的生长不仅会促进底质有机氮的降解,其自身分泌的代谢产物及残枝败叶的腐烂也会增加水体中各种形态氮的含量,增加对水体中各种氮素的滞留,在芦苇湿地区对水面漂浮物的打捞和对芦苇的及时收割是减少湖泊湿地氮素输入的一种有效途径。     

广东省农业信息化的现状与对策

农业信息化是新农村建设的重要环节。本文从农业网站、农业数据库、农业专家系统、农业管理信息系统、农业多媒体等5个方面阐述了广东省农业信息化发展的现状,并对农业信息化效果进行了分析,然后指出农业信息化中存在的问题,最后提出了发展建议与对策。     

麦套花生氮素代谢及相关酶活性变化研究

大田条件下,以花生“花育22号”为材料,研究了麦套花生的氮素代谢及相关酶活性变化情况。结果表明,麦套花生根叶游离氨基酸、氮素平均含量及根系可溶性蛋白平均含量高于单作;而叶片可溶性蛋白平均含量则低于单作。与小麦共生期间,麦套花生根叶硝酸还原酶（NRase）活性、谷氨酸脱氢酶（GDH）活性、叶片谷氨酰胺合成酶（GS）活性及谷氨酸-丙酮酸转氨酶（GPT）活性（除播后25 d）明显低于单作;整个生育期麦套花生根系GS平均活性及GPT活性高于单作花生。可见,花生苗期小麦遮荫对花生氮素代谢及酶活性有一定影响。     

田间管理对华北平原冬小麦产量土壤碳及温室气体排放的影响

选取华北平原冬小麦为研究对象,针对（1）秸秆移除;（2）秸秆表覆;（3）免耕;（4）秸秆深施;（5）施农家肥这5种典型的田间管理,使用农田自动温室气体测定系统对冬小麦农田全生育期进行了原位长期观测,并采用^13C自然丰度法对土壤碳的转化进行了监测,同时对冬小麦产量及生物量、土壤有机碳的变化进行了监测。结果表明,冬小麦产量及生物量高低顺序为施农家肥、秸秆深施、秸秆表覆、秸秆移除和免耕,而且土壤有机碳的更新也有同样的趋势;施农家肥能显著增加土壤有机碳而秸秆移除和免耕则会导致土壤有机碳的轻微下降;冬小麦甲烷的排放或吸收只占总增温潜势的不到1％,在进行统计总排放当量时基本可以忽略,N2O在总排放当量中的比例在2．55％-11．62％范围内;N2O的大量排放主要来自于拔节期及开花期,秸秆移除、施农家肥和秸秆深施会导致N2O排放在总当量中的份额增加至10％左右,而秸秆覆盖和免耕N2O排放在总排放当量中的份额只有3％左右,冬小麦农田总的温室气体排放88％以上来自于CO2的排放,特别是秸秆表覆和免耕95％以上来自土壤碳的损失而释放的CO2。总体来看,秸秆深施能保证较高的产量,减少碳的损失,增加土壤碳并产生相对较少的总温室气体排放量,是较好的固碳减排方式。     

Optimization of Media for Production of an Effective Yeast Biocontrol Agent Pichia membranefaciens

The growth of Pichia membranefaciens was studied using different nitrogen and carbonsources as substrates. Among nitrogen sources tested, soya peptone, yeast extract power,beef extract and polypeptone were relatively favorable to the growth of yeast. Thedensity of the yeast showed to be directly proportional to carbon sources supplementation.Glucose and fructose were good carbon sources for the yeast growth. However, lactoseshowed poor performance for the cell growth of the yeast. In this study, beef extractpresented a good synergic effect on the yeast growth with different carbonhydrates. Themedium for P.membranefaciens used glucose and beef extract as substrates. The higherconcentration of glucose and beef extract, the better growth of P.membranefaciens. Theaddition of chlorella growth factor (CGF) stimulated markedly the growth of P.membranefaci-ens. The increased concentration of CGF from 0.5 to 1% did not enhance the numbers ofP.membranefaciens. This result will help design a better strategy for scale-up produc-tion of P.membranefaciens.     

Analysis of QTL for Seed Dormancy and Their Response to Dry Heat Treatment in Rice(Oryza sativa L.)

Quantitative trait loci(QTL)controlling seed dormancy in rice were identified using recombinant inbred lines(RILs)population derived from the cross between a japonica variety Kinmaze and an indica variety DV85. Seeds of two parental cultivars and each RIL were harvested in 35d after heading.. The germination percentage of these seeds at 30℃for 7 days were measured as the degree of seed dormancy.. QTL analysis was performed with Windows QTL Cartographer 1.13a program by composite interval mapping.. A total of four QTL for seed dormancy were detected on chromosome 2(two regions),5 and 11,respectively.Phenotypic variation explained by each QTL ranged from 8.37 to 17.40%.. Responses of such loci to a dormancy-breaking treatment with dry heat were further detected. The results showed that two alleles of qDOR-2-1 and qDOR-5 from DV85 as well as the allele of qDOR11 from Kinmaze increased the seed dormancy,which seemed to be easily broken by dry heat treatment. Such loci of seed dormancy may be applied to rice genetic improvement.The allele of qDOR-2-2 from DV85 increased the seed dormancy,which could not be broken by dry heat treatment.     

玉米新不育胞质WB的线粒体类质粒鉴定

通过线粒体类质粒分析，表明华中农业大学发现的新雄性不育胞质WB带有S组特有的S1、S2类质粒，据此将WB确认为S组雄性不育胞质．     

苏云金芽胞杆菌新菌株的研究

为筛选对昆虫有高力的苏云金芽胞杆菌特异性菌株,从韩国不同地区土壤中筛选出两株对鳞翅目和双翅目昆虫具有杀虫活性的苏云金芽胞杆菌菌株K9805和K9903,它们分属于苏云金芽胞杆菌库斯塔克亚种和鲇泽亚种,形成典型的双金字塔型伴胞晶体,两菌株不但对小菜蛾、甜菜夜蛾具有较高的生命活性,而且对双翅目昆虫致倦库蚊有毒。K9805含有cry IAa,cy IAb,cry IC,cry ID和cry I基因,K9903含有cry IAa,cry IAb,cry IAc,cry IE和cry Ⅱ基因。     

韩国土壤中苏云金芽孢杆菌菌株的分离和鉴定

从韩国不同地区采集的６２０个土壤样品中分离出６７株苏云金芽孢杆菌,分属于１０种不同的血清型,毒力测定结果表明,在６７株分离株中,３５．８２％的菌株对鳞翅目昆虫具有生物活性,２２．３９％的菌株对双翅目昆虫有毒,３２．８４％的菌株对鳞翅目和双翅目昆虫都具有杀虫活性,８．９５％的菌株为没有杀虫活性的无毒菌株,其中对鳞翅目昆虫有毒的菌株产生典型双金字塔形伴孢晶体对双翅目昆虫有毒的菌株和无毒菌株都产生球形伴     

杂交稻秧苗形态性状与发根力间的相关和通径分析

通过对杂交稻秧苗形态性状与发根力之间的关系研究发现 :秧苗的形态性状与发根力呈正相关 ,决定发根力的主导性状是≤ 3cm白根数、茎基宽和绿叶数 ;分蘖数对发根力几乎没有直接影响。