Response of Stipa bungeana and Pennisetum flaccidum to urine of sheep in steppe grassland of north‐western China

Urine [12·3 g nitrogen (N) L^?1], collected from native Tan sheep in rangeland of the Loess Plateau in north‐western China, was applied to vegetation patches dominated by Stipa bungeana (C₃ grass) or Pennisetum flaccidum, (C₄ grass) at either 0, 1·0, 2·0 or 4·0 L urine m^?2 in early‐, mid‐, or late‐growing season, and herbage mass and tiller number per sample recorded, allowing calculation of the respective contributions of increases in tiller weight and tiller density to the response from N in urine. Such records were made three times in the growing season of application of urine, and at the end of the following growing season. Responses to urine were of the order of 1 and 5 kg herbage DM kg^?1 N applied for S. bungeana and P. flaccidum, respectively. Except for early‐season application, responses of S. bungeana were mainly expressed in the season following urine application whereas responses of P. flaccidum tended to be expressed within the year of urine application, although with a residual response in the following year. The general pattern was for a tiller density‐mediated response in the period immediately after application, followed later by a tiller weight‐mediated response. Taken together with other recent research, S. bungeana can be considered a stress‐tolerating species with a limited response to N application and P. flaccidum an opportunist species able to capitalize on increased N supply.     

The use of k-means and artificial neural network to classify cotton lint

The use of High Volume Instrument (HVI) to measure cotton lint characteristics produces high dimensional data. A model which utilized Kohonen Self Organizing Maps (SOM) to visualize cotton lint HVI data, k-means clustering technique to cluster the data and Probabilistic Neural Network (PNN) for data classification was designed and tested using Kenyan cotton lint. According to the model the Kenyan cotton lint can be grouped into four clusters, which were successfully classified by using PNN with a correlation coefficient (R-value) of 1.     

大蒜、生姜提取液对平菇上3种芽孢杆菌的抑制作用及其对平菇生长的影响

用大蒜、生姜提取液及其混合提取液,测定了其对平菇生产中常见的3种芽孢杆菌属细菌的抑制效果及对平菇生长的影响。结果表明,大蒜、生姜提取液对3种芽孢杆菌均有抑制作用。大蒜的抑菌效果好于生姜,但碱性条件下大蒜提取液抑菌效果下降明显,而生姜较为稳定;蒜、姜以4:6、5:5、6:4比例混合提取液在碱性条件下抑菌效果较好,适合平菇生产的碱性环境。其中,以5:5抑菌效果总体最好,在pH 9时均好于蒜、姜提取液。各处理平菇菌丝的生长与对照无显著差异;加入混合提取液可达到缩短平菇现蕾时间、平菇质地紧密、菌盖变小的效果;平菇产量以加入5:5蒜姜混合提取液的最高,4:6、6:4次之,其余则有所下降。     

稻田养鸡的研究进展及应用优势

随着现代农业的发展及推进,因农业污染而带来的环境问题越来越突出,为现代农业找寻可持久性发展的方法及向绿色农业的转型成为了当今一大主题.在此大环境下,生态种养不仅实现了物质能量循环利用,还能将生产中的废弃物无害化甚至有用化,在很大程度上解决了现代农业发展带来的污染及资源浪费等问题.从稻田生态种养中的稻—鸡模式出发,介绍其模式优势、经济效益、环境友好性及可操作性,以期对该模式的推广及发展提供参考.     

Performance of L-493 Macroprous Resin for Adsorption of Trihalomethanes from Water

Water, Air, & Soil Pollution - Microbial fuel cells (MFCs) have gained increasing attention as an effective pathway for wastewater treatment and electrical energy recovery. In this study, the...     

蔬菜标准化嫁接育苗关键技术

中国蔬菜种苗需求量逐年上升,且前景广阔。同时对于种苗质量的要求也越来越高。本文详细介绍茄果类和瓜类标准化嫁接育苗技术与条件。     

穴式铺膜播种机设计问题研究

在现有铺膜播种机的基础上,提出设计穴式铺膜播种机时应注意的问题。并对地膜撕裂、地膜一边紧一边松、覆土要求、精量穴播和种子、膜孔错位5个关键问题进行了研究分析。      

Test of size-specific mass selection for Nile tilapia, Oreochromis niloticus L., cage farming in the Philippines

One generation of mass selection based on the collimation procedure (early culling of large fry) was applied on Nile tilapia, Oreochromis niloticus L., in net cages set in Laguna de Bay, Philippines. The objective was to test the effectiveness of a low-cost, small-scale broodstock improvement procedure in this culture environment. Directional selection was performed in two steps after initial removal of large fry at 21 days. Selection of parents and testing of the offspring were also conducted in hapa net cages set up in Laguna de Bay. The selection resulted in a significant positive response of 3% relative to the control, which represents a projected 34% gain over 5 years in Laguna cage culture. The realized heritability is ≈16%.