Biological nitrogen fixation in a grazed perennial grass/clover ley and correlation with herbage and soil variables

In a grazed grass/clover pasture, biological nitrogen fixation (BNF) is a source of nitrogen (N). The determination of this N input and how it is influenced by N, phosphorus (P) and potassium (K) in the soil, is complicated by grazing animals, which cause variation in defoliation and soil mineral content in both space and time. In a perennial grass/clover ley on a commercial Danish organic farm, exclusively grazed by dairy cows, we investigated BNF, clover proportion of the herbage, accumulated dry matter of clover and N, P and K concentrations in separates of clover and grass in relation to inorganic concentrations of N, P and K in the soil. The ¹⁵N natural abundance technique was used to determine the proportion of clover N derived from the atmosphere (pNdfa) using grass as a non-fixing reference. In September 1997, soil and biomass sampling was carried out on 81 randomly selected plots. The value of pNdfa was on average 0.6, ranging from 0.12 to 0.96 and BNF exhibited a significant but weak correlation (r=0.432) with accumulation of dry matter in clover. For the significant correlations, r varied between −0.403 and 0.648. The proportion of clover in the sampled herbage averaged 48%, ranging between 18 and 78%, but varied independently of BNF. Due to a high concentration of P and moderate to high concentration of K in the soil, clover and grass were well supplied with P and K, which was confirmed by the concentrations of K and P in shoot material.     

Short Communication A low morphine-containing accession of Papaver somniferum suitable for seed production*

A total of 140 Indian accessions of Papaver somniferum were raised under the subtropical conditions of Lucknow, India. They were screened for major alkaloids present in the capsules and peduncles, using a TLC-densitometry procedure. An accession containing the narcotic alkaloid morphine at as low a concentration as 0.05% in its capsules has been identified. The accession has good agronomic traits.     

Inheritance of tolerance to leaf iron deficiency chlorosis in tomato

By using two tomato genotypes, 227/1 (Fe chlorosis susceptible) and Roza (Fe chlorosis tolerant), and their reciprocal F₁, F₂ and BC₁ generations, the inheritance of tolerance to leaf Fe deficiency chlorosis of Roza was studied. Plants were grown in a nutrient solution and subjected to 2.0 × 10^–6 M Fe EDDHA and 10 mM NaHCO₃ to induce Fe deficiency stress by stabilization of pH to 7.8–8.2. A rating scale of 1–3 for chlorophyll was used and both monogenic and polygenic inheritance hypotheses were tested. Better responses to Fe deficiency, as measured by SPAD meter values, were obtained from the cross Roza × 227/1 than from the reciprocal cross. Data from F₂ and BC₁ suggest Fe chlorosis tolerance of Roza is to be controlled by polygenic loci with a relatively high additive effect.     

旗叶期缺磷及去蘖对小麦光合特性和磷分配的影响

采用石英砂培养方法并去除或保留分蘖，研究了旗叶期缺磷对大穗型小麦CA9325和多穗型晋麦2号（JM2）生长后期旗叶光合和蒸腾速率、干物质和磷在体内分配以及最终产量的影响。结果表明: ⑴旗叶期缺磷一段时间后降低小麦旗叶的光合和蒸腾速率。不同供磷水平下，去蘖使小麦旗叶光合和蒸腾速率大都高于同期未去蘖的；⑵旗叶期缺磷几乎导致两品种所有器官和整株干物质和磷的积累降低，去蘖的小麦籽粒干物质和磷总量占整株的比例均高于未去蘖的，说明缺磷促进小麦各营养器官的磷向籽粒转移；⑶主茎干物质和磷的积累以CA9325高于JM2，而JM2则以分蘖占优势，这与JM2分蘖数较多有关；⑷ 不论供磷还是缺磷，未去蘖的CA9325籽粒产量低于JM2，而去蘖后则相反。不同库容量的CA9325千粒重和籽粒磷含量均高于JM2。全生育期供磷条件下的磷吸收效率，以未去蘖的CA9325显著高于JM2，去蘖后两品种间无明显差异。     

缺磷胁迫对不同玉米幼苗生长的影响

营养液砂培4种不同玉米自交系材料,设置0.25mol/LKH2PO4全磷(对照)、0mol/LKH2PO4(缺磷)两种处理,于5、7、9、11d时考察幼苗生长指标。对缺磷胁迫下4种不同基因型玉米自交系生长的研究表明,低磷胁迫对040651、044191地上部分的抑制大于根系,根系的相对干生物量明显高于地上部分的相对干生物量;从相对株高和相对叶面积的研究显示,编号为040651的自交系受缺磷胁迫的影响小于其他3个自交系材料。缺磷胁迫下4种不同基因型玉米自交系根系形态的研究显示:缺磷胁迫诱导玉米根伸长,根系表面积增大,根冠比显著增加。     

Importance of P uptake efficiency versus P utilization for wheat yield in acid and calcareous soils in Mexico

There are large agricultural areas in the world where wheat yields are limited by low phosphorus (P) availability. Breeding for P uptake and P utilization efficiency may reduce this problem. This study was conducted to determine the contribution of P uptake and utilization efficiency to grain yield of selected spring wheat genotypes in different environments. Thirty-eight semidwarf spring bread wheat (Triticum aestivum) genotypes were grown in two experiments in Mexico, each on an acid Andisol under rainfed conditions and on a calcareous Aridisol with irrigation, without (−P) and with 35 kg P per ha fertilized (+P). Without P fertilization, grain yield ranged from 0.8 to 4.6 t ha⁻¹ in the acid soil and from 2.4 to 5.2 t ha⁻¹ in the calcareous soil. With P fertilization, this range was even larger. Under conditions of P deficiency, i.e. in the acid soil at −P and +P (high P adsorption) and calcareous soil at −P (P-depleted soil), P uptake explained 71–100% of the variation in grain yield, and was highly correlated with grain yield (r=0.79–0.95). In contrast, at +P in the calcareous soil, P utilization efficiency explained 60–63% of the variation in grain yield. Here, low grain P concentration was related to high grain yield (r=−0.40 to −0.59). In the calcareous soil, the harvest index was correlated with grain yield, irrespective of the P level. In the acid soil, post-anthesis P accumulation was important. It was positively correlated with grain yield, whereas in the calcareous soil, no post-anthesis-P accumulation occurred. Here, grain P accumulation at maturity was completely determined by translocation of pre-anthesis shoot P. We conclude that the combination of improved P uptake and P utilization efficiency in the same genotypes requires selection under both high and low-P conditions.     

黄浦江上游养鸭业污染源调查——鸭场污染研究材料之一

鸭子每小时每斤体重排干粪1.02克,每只鸭子年排干粪12.22kg。鸭粪中含有大量氮、磷、微生物和耗氧污染物。青浦县每年排放干鸭粪3.28～4.88万吨,松江县为1.25～2.17万吨。其中24％左右进入水体。污染物的单位水面负荷量相当高,特别是磷、氮营养物和微生物污染物。这必然引起水体富营养化和降低饮用水的质量。     

Uterine Inertia due to Severe Selenium Deficiency in a Parturient Mare

A 12-year-old, multiparous, parturient show jumper embryo-recipient mare presented at a veterinary hospital, seven days past her due date and with a dilated cervix, for evaluation of mild colic. Gastrointestinal or metabolic abnormalities and fetal maldispositions were excluded as causes of dystocia, and a diagnosis of uterine inertia was made. There was no uterine response to oxytocin treatment. A live filly was delivered via C-section, and severe selenium deficiency was eventually confirmed in the mare, her offspring, and in the herd of origin. The filly was born with severe white muscle disease and required intensive treatment. This report suggests that selenium deficiency is an underlying cause of equine uterine inertia in the absence of other causes of dystocia.     

中兽医治疗公牛繁殖障碍方剂的组方规律

探讨中兽医治疗公牛繁殖障碍性疾病方剂的组方规律。方法:收集《中国兽药典》、中兽医专业书籍及《中国知网》数据库中相关文献报告中的方剂,运用Excel2010软件录入方剂信息,建立相关方剂数据库。统计方剂中各个药物使用频次、分类、归经以及在不同证型中的分布。将构建的数据库导入SPSS21.0药物对与各证型间关联规则,得出各证型的核心药物对、组方规律。分析收集的98首方剂发现,中兽医治疗公牛繁殖障碍方剂有3种类型,治疗肾阳虚68首、肾阴虚23首、阴阳两虚7首。涉及101种中药,频次大于8的有39种中药,频次最高的前6位中药的分别是熟地、菟丝子、淫羊藿、茯苓、枸杞子、甘草。98首方剂中核心药物对19对,频次最高的药物对是枸杞子-菟丝子,29次。临床实践中公牛繁殖障碍以肾阳虚、肾阴虚证型最为常见,功效以补肝肾之阳、生精益髓、培元固本的补虚药为主,且具有肝肾同补作用的中药居多。药物归经主入肾经、肝经,不同证型所使用的核心药物对也不同,临床治疗时可按照这些药对为核心组成方剂,为中兽药新方剂的研发提供了组方思路与线索。     

一次性消化测定饲料中粗蛋白、钙、磷的研究

本文采用硫酸—过氧化氯消化样品，连续测定饲料中的粗蛋白、钙、磷的含量，经过比较，此方法简便易行，结果令人满意