4个臂形草品种在闽南地区的生育特性及其相对饲用价值研究

对4个臂形草Brachiaria品种进行3年的生育特性及其品质分析,结果表明,参试品种均可在闽南地区越夏越冬,热研3号和热研6号的开花期均在6月上中旬,杂交臂形草Mulato1与Mulato2开花期比热研6号推迟2个月左右;年均草产量以杂交臂形草Mulato1最高,鲜草产量与热研6号臂形草达极显著水平;营养成分分析结果显示,参试品种分蘖期粗蛋白含量以杂交臂形草Mulato1最高,达9.38%,粗脂肪和钙含量以热研6号最高,相对饲用价值均达100%左右。杂交臂形草Mulato1可作为刈割型牧草在闽南地区推广种植。     

应用MTT比色法评价不同牛血清促细胞生长作用

细胞培养过程中血清的选择对细胞的促生长增殖具有重要作用。本试验分别以商品新生牛血清、自制新生牛血清、自制成年牛血清培养成纤维细胞、骨髓瘤细胞、杂交瘤细胞,通过MTT比色法来判断细胞的增殖能力,进而对血清质量作出评价。结果表明,自制新生牛血清具有良好的促细胞生长作用(相对生长率＞0.96),并且3次试验结果比较差异不显著(P＞0.05),具有较好的重复性;而成年牛血清和无血清空白对照组促细胞作用不明显。因此应用MTT比色法能够评价血清质量。     

我国农产品比较优势与农业财政政策取向

在分析了我国农产品比较优势的特征基础上,提出了提升我国农产品比较优势的基本策略和财政政策。基本策略包括调整和优化种植业结构、加快发展畜牧水产业、发展农产品加工业、优化农业区域布局和调整农产品进出口战略;财政政策包括增加农业投入、优化支出结构、加快农村税费改革进程和支持建立农业灾害保障机制等。     

土壤相对含水量对阿月浑子叶片内源激素含量的影响

研究了土壤相对含水量对阿月浑子叶片内源激素含量的影响。结果表明，随着土壤相对含水量的降低，阿月浑子叶片ABA和IAA含量呈上升趋势，ZA含量呈下降趋势；但在80％～40％的土壤相对含水量范围内，ABA/IAA的比率随着土壤相对含水量的降低基本不变；干旱胁迫下，阿月浑子幼苗通过激素调节保持相对稳定的IAA/ABA比值可能是其抗旱性强的内在机制之一。     

杭州植物园的“冷岛”效应

选择了具有代表性的4个点、在春、夏、秋、冬分8：00、14：00、20：00三个时段进行了气温观测，得到热岛强度和干岛强度以晚上20：00最大，四季中以夏秋季节最大，获得最大热岛强度为6℃，四季平均约为2℃，最大的干岛强度为30％，四季平均约为9％，植物园同城区之间存在显著的热岛效应和干岛效应。     

湖南省南岳原生性森林群落的研究--Ⅴ.物种多样性与相对多度分布格局

对湖南省南岳原生性森林群落植物物种进行了研究.结果表明,其多样性水平比较高,接近山地季雨林的水平,其中,群落草本层的多样性水平最低,乔木层和灌木层的较高.在5种不同的原生性森林群落类型中,乔木层和草本层的物种多样性以类型3(包石栎 锐齿槲栎 甜槠 多脉青冈-箬竹-求米草群丛)的最高, 以类型4(甜槠-花竹 云和新木姜子-淡竹叶 莎草群丛)的最低;灌木层物种多样性以类型3(包石栎 锐齿槲栎 甜槠 多脉青冈-箬竹-求米草群丛)的最高, 类型2(长叶石栎 多脉青冈-尾叶山茶-求米草群丛)的最低.植物物种相对多度分布格局的测定结果表明,分割线段模型中的序列-多度模型适宜于拟合乔木层物种与其个体数量之间的关系,对数级数分布模型适宜于拟合乔木层和灌木层;其α指数值较高,说明群落物种多样性水平较高,接近山地季雨林.分析表明, 测定群落植物物种多样性时, 如果仅用1～2个公式计算, 可能会出现错误的结果;此外, 提出了几何级数分布模型--极大值算法.     

The relationship between open windspeed and windspeed reduction in shelter

Windspeed reduction in shelter is generally expressed relatively and is usually assumed to be independent of open windspeed. The purpose of this study was to re-examine the relationship between open windspeed and windspeed reduction in shelter using windspeeds and wind directions measured for two windbreak systems at various distances from the windbreaks and with three windbreak porosities. Optical windbreak porosities were estimated from digitized color photographs using an intelligent (trainable) image processing program. Relative windspeed reduction in shelter was found to be related to the open windspeed. There existed a threshold windspeed at approximately 5 m s^–1, below which relative windspeed reduction varied but generally decreased as the open windspeed increased. Above the threshold windspeed, open windspeed did not have an effect on relative windspeed reduction in the sheltered zone. Using the threshold windspeed reduction, the authors propose an index to evaluate the effectiveness of a windbreak for the overal windspeed protection.Published as Journal Series No. 10815 of the Agricultural Research Division, University of Nebraska.     

Morphological and water-stress characteristics of three Douglas-fir stocktypes in relation to seedling performance under different soil moisture conditions

This one-time greenhouse study examined the phenology, morphology, frost hardiness and response to moisture stress of three Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) stocktypes from the same seed lot. The types were mini-plug^TM transplants (MPT), 1+1 bareroot transplants (1+1), and 2+0 bareroot seedlings (2+0). In late summer and fall before lifting, 2+0 seedling set bud before 1+1 seedlings, 1+1 seedlings before MPT seedlings. The 2+0 seedlings appeared slowest to acquire frost hardiness in fall and seemed to deharden most rapidly in spring. Although the 2+0 seedlings were taller than the MPT stocktype, MPT and 2+0 seedlings were relatively similar in other morphological respects, but 1+1 seedlings were much larger. All stocktypes were potted on January 20, 1989, placed in a greenhouse, and subjected to 39%, 18%, 16%, or 6% soil water content (% dry weight) until the end of the experiment in mid-July 1990. The largest decrease in pre-dawn xylem water potential occurred with 16% and 6% soil water content; pre-dawn xylem water potential averaged over the three stocktypes generally declined 219% from low to high soil moisture stress. The 1+1 seedlings used more water than the other two stocktypes, and at maximum soil moisture stress, plant moisture stress increased in the order: MPT <2+0<1+1. During the 6-month greenhouse experiment, the larger 1+1 stocktype showed the most absolute growth, but the smaller stocktypes grew more on a relative scale. Growth of the stocktypes appeared to be related to differences in morphology and water-use patterns as the seedlings competed for available water within each pot. The results show that MPT seedlings, a new stocktype, performed as well as the more traditionally used 2+0 and 1+1 seedlings and that stocktype selection is important in reforestation efforts.     

Yields of cocoa/kola intercrops in Nigeria

The yields of two intercropped cocoa/kola plots at the Cocoa Research Institute of Nigeria, Ibadan, (W8/1 and C3/1), were compared with the yields of monoculture plots (N4/A and W1/2). It was found that 1.75 ha of monoculture plot gave the same crop yield (kg/ha) as 1.00 ha of mixed crop. The cocoa component started fruiting earlier than kola and also continued to yield annuall so there was no crop failure in any year.