Analysis of genetic variability and agronomic performance of Indian lettuce (Lactuca indica L.)

Genetic Resources and Crop Evolution - Lactuca indica L. is an undomesticated medicinal crop in the Asteraceae family. The study was carried out to identify elite genotypes for lettuce cultivation...     

Selenium Concentration in Spring Wheat and Leaching Water as Influenced by Application Times of Selenium and Nitrogen

ABSTRACT

Selenium (Se) deficiency in Scandinavian soils is a common problem, and crops generally contain inadequate amounts to meet human need. This study shows a relationship of the Se concentration in spring wheat (Triticum aestivum L., c.v. ‘Helena’) and leaching water with timing of nitrogen (N) [as ammonium nitrate (NH₄NO₃)] and Se [as sodium selenate (Na₂SeO₄)] application. Ammonium-nitrate was applied by two methods (i) whole amount at sowing and (ii) in split application as 75% at sowing and 25% at stem elongation. Selenate was applied at cereal growth stages after sowing, e.g., tillering, stem elongation, head emergence, and milking. Split N application in comparison to one N application increased the grain protein content from 12.1 to 13.7 mg g^{? 1}, and grain Se was increased from 0.8 to 1.1 mg kg^{? 1} when Se was applied at stem elongation and from 0.6 to 0.9 mg kg^{? 1} when applied at heading. The highest Se concentration in plant was achieved with the split N application and Se application at stem elongation or heading. Selenium leaching losses increased with increasing selenium concentration in the wheat grains. No differences in Se leaching losses were obtained with split N application. Applying selenate and ammonium-nitrate together after tillering increased the grain Se concentration, but did not affect the potential leaching of Se, and thus could be considered as an appropriate time of application of these elements.     

Successful Hybridization of Acipenser Species Using Cryopreserved Sperm

Successful hybridization of sterlet (Acipenser ruthenus) × Siberian sturgeon (Acipenser baeri), sterlet × Russian sturgeon (Acipenser gueldenstaedti) and sterlet × European sturgeon (Acipenser sturio) was carried out for the first time using cryopreserved semen of sturgeon males and sterlet × sterlet crosses as controls. Sperm of all three species was diluted with a cryodiluent composed of 23.4 mM sucrose, 0.25 mM KCl, 30 mM Tris (pH 8.0) and 10% methanol. The samples were frozen in plastic straws in the vapor of liquid nitrogen at the height of 3 cm above the level of nitrogen for 3 min. Following thawing approximately 3000 sterlet eggs were fertilized with six straws of frozen-thawed sperm. The hatching rate with sterlet sperm was 30.6% while the hatching rate of A. ruthenus × A. baeri, A. ruthenus × A. gueldenstaedti and A. ruthenus × A. sturio hybrids was 50, 17.4 and 34%, respectively. Morphometric markers as well as random amplified polymorphic DNA (RAPD) assay was used to verify interspecific hybridization.     

Efforts to chemically induce mutations for cytoplasmic male sterility in petunia. I. Field experiments

Summary In the period 1980–1984 about 70000 selfed seeds of the petunia cultivar Blue Bedder were treated with the chemical mutagens ethidium bromide (EB) and ethylnitroso urea (ENU) with the intention to induce (new sources of) cytoplasmic male sterility (CMS). This work resulted in 27 stable male sterile MS-plants, all derived from the ENU-treatments.Crosses with the normal fertile type and with material carrying restorer genes for the common type of CMS in petunia were made. Results obtained from some MS-plants raise a presumption of genic male sterility, probably of the dominant type, having been induced. More detailed investigations are underway.     

管理肉种鸡的产蛋行为

法国和讲法语的北非国家是至今为止小体型、轻体重肉鸡的最大市场。许多法国种鸡育种公司正对这一需求作出反应,如肉鸡生产商Goasduff公司（一个管理出色的家族型企业,对他们的父母代鸡群定下了明确的目标）就拥有大部分小型种鸡。他们采取特殊的管理措施以取得合理的产蛋性能。