挖掘频繁闭项集(CFI)在许多实际应用中起着重要的作用.传统的数据挖掘算法中常用FP增长算法和Apnori算法来挖掘频繁项集.然而,内存需求和计算成本成为CFI挖掘算法的瓶颈,尤其是在从大型数据集中挖掘频繁闭项集时,是一个重要和具有挑战性的问题.针对上述问题,提出一种基于云计算的MapReduce框架的并行AFOPT-close算法,使MapReduce可广泛地用于处理大型数据.此外,用于检查频繁项集是否为完全闭的有效并行算法也要求MapReduce平台进一步完善其性能.

Effect of paclobutrazol(PP333) on the growth of Festuca arundinace planted in greenhouse was studied by setting 3 spraying time and 4 concentration levels in contrast with Festuca arundinace not sprayed with PP333 to explore the best spraying time and the best concentration of PP333.The results show that spraying 100～200mg/L PP333 at seedling stage has obvious effect on plant height,leaf width,stem diameter,aboveground biomass,and underground biomass of Festuca arundinace.Spraying time is the major factor affecting the growth of Festuca arundinace.The effect of PP333 on Festuca arundinace with the same treatment time increases with the increase of PP333 concentration.

The quantity of ammoniated bacteria,nitrifying bacteria,denitrifying bacteria,sulfur bacteria,anti-sulfur bacteria,fungi and actinomyces around Festuca roots planted in rotted rice straw substrate and soil substrate was determined to study the effect of different substrates on risophere microflora quantity of Festuca.The results showed that the population diversity and uniformity of Festuca risophere microflora planted in rotted rice straw substrate were higher than those planted in soil substrate,which indicates that the rotted rice straw substrate with good basic nutrition is an ideal substrate for planting turf grass.

高羊茅在我国有着广泛的种植面积,是多年生冷季型牧草和草坪草.介绍了高羊茅的再生体系,从它的转化方法、转化目标、影响因素、生物安全问题等方面综述了高羊茅的外源基因转化研究进展.