氮肥施用量及施用时期对小麦品质性状的影响

为了探明不同氮肥运筹对西南麦区小麦品质性状的影响,以小麦品种(系)R210和川农25为材料,采用2因素3水平随机区组设计研究了施氮量及施氮时期对小麦品质性状的影响.结果表明,蛋白质及其组分含量、干面筋含量、沉淀值和稳定时间、粉质质量指数均随施氮量的增加而提高.施氮时期对品质性状的影响表现为:全施底肥有利于提高沉淀值、粉质质量指数及醇溶蛋白含量;采用底肥∶三叶期肥=1∶1的方式有利于提高GMP含量;采用底肥∶三叶期肥∶孕穗期肥=5∶2∶3的方式,有利于提高干面筋的含量,降低弱化度.不同品种的优质栽培方式不同,R210以底肥∶三叶期肥∶孕穗期肥=5∶2∶3,施用纯氮18 g/m2品质最优,川农25以全施底肥,施用纯氮18 g/m2品质最优.     

调制方式对苜蓿青干草干燥特性和营养品质的影响

本研究以种植第2年处于初花期的紫花苜蓿(Medicago sativa)为材料,设压扁+喷碳酸钾（2.5%）、压扁茎秆、自然晾晒和阴干4种青干草调制方法,以105 ℃烘干为对照,研究不同调制方法对苜蓿干燥特性和营养品质的影响,并对干草质量进行综合评价。结果表明,除对照外,参试调制方式的苜蓿干燥速率均呈现先快后慢的趋势;对照、压扁+喷碳酸钾（2.5%）都能加速干燥,减少干草营养物质损失;常规晾晒虽缩短了干燥时间,但对干草品质的保持效果不显著。采用灰色关联分析对参试方法的调制效果进行综合评价表明,对照的综合表现最好,其次是压扁+喷碳酸钾（2.5%）,该晾晒方法快速、简便、实用,在生产中值得推荐。     

Flavan-3-ols and procyanidins in grape seeds: biodiversity and relationships among wild and cultivated vines

Flavan-3-ol monomers and polymers composition of seeds from wild (17) and autochthonous (8) Vitis vinifera grapes growing in northern Tunisia were evaluated. Wild grape seeds were spherical with a small beak and relatively a high seed/berry ratio (~ 18.1%w/w). Local cultivars developed pyriform-shaped seeds with a well-developed beak representing on average 2.2% of total weight of the berry. Flavanol concentrations ranged between 40.9 and 67.5 mg/g FW in seeds from wild accessions and between 48.9 and 96.7 mg/g FW in seeds from cultivated grapes. Differences between accessions were highly significant (p < 0.01) and seeds from cultivar ‘Boukhasla’ showed the highest polyphenols content. Among flavan-3-ol monomers, (+)-catechin was predominant for all ecotypes and generally their abundance was: (+)-catechin (Cat) > (?)-epicatechin (Ec) > (?)-epicatechin-3-O-gallate (EcG). The Cat/Ec ratio was approximately 1.7 for wild grapes while it was about 2.5 for cultivated grapes. Procyanidins in wild seeds differed from cultivated ones by a lower mDP and higher proportions of galloylated derivatives, likely to affect fruit bitterness and astringency. (?)-epicatechin was the main extension subunit in grape seed procyanidins, reaching on average 52% in wild and 58% in cultivated seeds. Hierarchical cluster analysis based on seeds morphometry and procyanidin profile indicated close proximity between some wild and cultivated grapes suggesting that some cultivars derived from ancestral events of local domestication or cross hybridization with native wild plants.     

Polyol production by chemical modification of date seeds

Polyol production from chemical modification of date seeds has been investigated through oxypropylation and liquefaction techniques (using organic solvents in the presence of a catalyst). The obtained products were characterized using infrared spectroscopy analysis, ¹H NMR, thermogravimetric analysis and other parameters such as hydroxyl number (I_OH) and viscosity. Results showed that 93% of the solid substance was converted into polyol in the oxypropylation reaction at the date seeds/propylene oxide ratio of 0.25 and 10% potassium hydroxide at 160 °C. The oxypropylated product has I_OH of 779 mg KOH/g and viscosity of 6.9 Pa s. Regarding the liquefaction technique, results show that a yield of 95% was obtained at the date seeds/liquefying solvent ratio of 0.25 in 60 min of reaction at 160 °C. The liquefied product shows I_OH of 336 mg KOH/g and viscosity of 0.9 Pa s.     

Effect of industrial dehydration on the soluble carbohydrates and dietary fiber fractions in legumes

The effects of soaking, cooking, and industrial dehydration treatments on soluble carbohydrates, including raffinose family oligosaccharides (RFOs), and also on total dietary fiber (TDF), insoluble dietary fiber (IDF), and soluble (SDF) dietary fiber fractions were studied in legumes (lentil and chickpea). Ciceritol and stachyose were the main alpha-galactosides for chickpea and lentil, respectively. The processing involved a drastic reduction of soluble carbohydrates of these legumes, 85% in the case of lentil and 57% in the case of chickpea. The processed legume flours presented low residual levels of alpha-galactosides, which are advisable for people with digestive problems. Processing of legumes involved changes in dietary fiber fractions. A general increase of IDF (27-36%) due to the increase of glucose and Klason lignin was observed. However, a different behavior of SDF was exhibited during thermal dehydration, this fraction increasing in the case of chickpea (32%) and decreasing in the case of lentil (27%). This is probably caused by the different structures and compositions of the cell wall networks of the legumes.     

海水经济鱼类遗传育种研究进展

近二三十年来,海水养殖方式与设备的不断发展与完善,促进了海水养殖业的发展。但是,由于海水经济鱼类缺乏优良品种,大多数养殖种类为野生种或半野生种,许多养殖种群在累代繁殖后,出现品质退化、生长速度慢、发病率高等不良症状,严重地阻碍着海水经济鱼类养殖业的发展。因此,近年来,世界各国纷纷加强海水鱼类的遗传育种研究工作,     

Early weaning of winter flounder (Pseudopleuronectes americanus Walbaum) larvae on a commercial microencapsulated diet

Like most small marine fish larvae, the stomachs of winter flounder Pseudopleuronectes americanus are undeveloped at first feeding and have relatively reduced digestive capacity. This work was undertaken to test whether larvae at the onset of stomach differentiation (larval size about 5.5 mm) could be early weaned onto a commercial microencapsulated diet. We assessed the effect of early weaning by first comparing growth performance (standard length, total protein content and age at metamorphosis) of larvae fed enriched live prey from first feeding to a size of 5.5 mm and then reared on three different feeding regimes until metamorphosis: (1) live prey (LP) as a control group; (2) mixed feeding of live prey and microencapsulated diet (LP‐ME); (3) exclusively microencapsulated diet (ME) after fast weaning over 4 days (to a larval size of 6.2 mm). No differences were observed between larval development in the two first groups, which began metamorphosis at 40 days old. The larvae of the third group showed significantly slower growth that resulted in a delay of 4 days in the onset of metamorphosis. Differences in live prey availability between the treatments and the short transition period to allow the larvae to adapt to the new diet were identified as possible contributing factors to the slower growth and to the delay in metamorphosis of early weaned larvae. In a second experiment, the transitional weaning period was increased until the larvae were 6.6 mm in length. Weaning at that size resulted in no slowing of growth or delay in metamorphosis, suggesting that the feeding schedule was adequate.     

植保四轴飞行器的模糊PID控制

针对当前植保四轴飞行器在作业过程中自身载荷发生改变后的飞行控制性能下降、抵抗环境扰动能力差的问题,该文改进了传统比例积分微分(proportion,integration,differentiation,PID)控制算法,提出了一种模糊PID控制算法。该文通过研究四轴飞行器的姿态解算和飞行原理,设计了以STM32系列的单片机为核心处理器的四轴飞行控制系统。采用AHRS模块实时解算飞行器姿态参数,结合模糊控制和PID控制算法调节电机的输出量来控制飞行姿态。试验结果表明:与传统PID相比,模糊自整定PID控制算法适应性强,参数整定简单,系统的动态响应能力和稳定性获得了提高,实现了四轴飞行器的稳定飞行。该文为植保无人机控制算法研究提供了一定的参考。     

气候条件对冬小麦穗粒数的影响研究

长期定位试验研究气候条件对冬小麦穗粒数的影响结果表明 ,冬小麦穗粒数主要受返青后 5日滑动平均气温首次≥ 4℃之日～雌雄蕊原基分化时 (即拔节开始天数 )的影响 ,并受其至挑旗期平均最低气温和至抽穗期日照时数的制约。各因素对冬小麦穗粒数的影响大小依次为天数 >日照时数 >平均最低气温。冬小麦高产栽培还应协调好穗数、穗粒数和千粒重三者之间的关系