Changing rice farmers' pest management practices through participation in a small-scale experiment

Asian rice farmers commonly spray insecticides in the early stages of the crop to control leaf-feeding insects. The most common leaf feeder during this period is the leaf folder. Research shows that these sprays are usually unnecessary as the damaged crops mostly recover. It appears that farmers spray to control leaf folder because of misperceptions. We explored the use of farmer participation to change these misperceptions by inviting farmers to test a simple rule-of-thumb or 'heuristic': 'Do not spray against leaf folders for the first 30 days after transplanting (or 40 days after sowing)'. About 77% of the 101 participating farmers reported that yields of rice in their test plots were not significantly different from yields in their control plots. Before participating in the evaluation exercise, about 70% of the farmers applied their first insecticide sprays during the first 30 days after transplanting. In the first year after participation, 20% applied insecticides in the first 30 days and this was further reduced to 11% in the second year. The mean number of insecticide sprays was reduced from 3.2 to 2.0. Farmers' attitudes towards leaf-feeding insects has also changed. Before participation, farmers believed these insects cause yield loss (87%), severe damage (77%) and had to be sprayed early in the season (62%). After participation, these were reduced to 9%, 28% and 10%, respectively. Through information from research distilled into a 'high science-low tech' decision rule, farmers can readily derive a test hypothesis from it, evaluate itusing a simple experiment, learn its results and change perceptions and practices.     

夏播晚熟玉米的叶片数和积温研究

[目的]研究夏播玉米叶片数、积温及其对生育期的影响。[方法]研究丹玉6号晚熟玉米,不同播种方法、不同播期的叶片总数、叶片伸展期所需天数积温、生育期和适宜追肥期。[结果]麦套玉米,栽培因素使玉米达不到应有的叶片总数,说明环境条件不利于玉米生长发育,影响其产量。[结论]改革现有的播种方法,改麦田套种玉米为麦收后直播。     

改进Otsu法的冠层图像分割及银杏叶面积指数估测1）

基于Otsu法对冠层图像临界处分割不准确的缺点,结合类间方差以及类内聚度对阈值选取及图像分割效果的影响,提出了一种改进阈值选取算法。利用银杏冠层图像分割实例进行比较,同时进一步拟合了图像信息与叶面积指数间模型,结果表明：（1）该改进法较传统Otsu法可得到更好的分割效果;（2）以分割得到的前景像素比值作为自变量,叶面积指数为因变量,拟合得到的模型能较好的描述冠层图像信息与叶面积指数间的关系;（3）提出了一种即时无损并快速可靠的叶面积指数估测方法。     

蓖麻离体再生体系的建立

以蓖麻品种淄5号和秀蓖2号的成熟种子胚轴为外植体,在含0.25 mg/L 苯基噻二唑基脲(TDZ)的改良MS(蔗糖20 g/L、琼脂9 g/L)固体培养基上诱导生芽。结果显示：淄5号和秀蓖2号平均每个外植体可产生4个不定芽,2品种间产生不定芽的数量没有明显差异;不定芽经伸长、诱导生根能发育成完整的植株,2品种在根分化能力上没有明显差异。综合分析,这2个蓖麻品种基因型对体外再生体系的建立没有明显影响。     

丹参叶面积指数与干物质积累模拟模型

引用“辐热积”概念,建立叶面积指数模型和基于光合的干物质积累模型。将叶面积指数模型和高斯积分法相结合,依据丹参的冠层结构特点,建立三层模型。选用光合直角双曲线模型,并考虑温度对最大光合速率的影响,量化丹参的呼吸消耗;去除生长后期气温下降、光照减弱等因素造成丹参地上部分枯萎、干物质减少,使后期模拟更为精确,从而建立基于生理生态过程的丹参光合生产和干物质转化积累动态模拟模型。用均根方差、相对误差及拟合指数对独立的试验2数据进行检验,叶面积指数和干物质模型模拟值和实测值间决定系数R≥0.992,模拟值和实测值间符合度达到极显著水平,回归相对误差均在10%左右,拟合指数均接近于1。     

石灰岩特有植物圆叶乌桕土壤与叶片化学元素含量特征

对石灰岩特有植物圆叶乌桕与同属的乌桕、山乌桕叶片及其生长地土壤化学元素进行测定,比较三者化学成分特征,分析了圆叶乌桕在广东石灰岩地区的环境适应特点.结果表明:圆叶乌桕生长地的有机质、全N及全P含量均高于乌桕、山乌桕生长地,N素和P素有效率较低,速效N仅占全N含量的6.88％,速效P仅占全P的4.77％,全K含量偏低,但圆叶乌桕生长地速效K含量(151.8 mg· kg-1)达到土壤速效K含量对应的适量K(125～155 mg·kg-)水平等级,属适量K型土壤,交换性Ca及交换性Mg含量均高于乌桕、山乌桕生长地,微量元素含量排序为Mn＞ Pb ＞Cr＞ Zn＞ Ni＞ Fe＞ Cd＞ Cu,全Pb、全Zn及全Cu含量均未超过国家规定的3级标准.圆叶乌桕叶片Ca含量(25.24 g·kg-1)、Cd含量(0.45 mg· kg-1)高于乌桕、山乌相.土壤中植物营养元素含量较低的元素如K、Fe和Cu在圆叶乌桕叶片中的生物吸收系数较高,而土壤中含量较高的元素如N、Ca、P、Mg、Mn和Zn在其叶片中生物吸收系数较低.在高温干旱的胁迫下,圆叶乌桕叶片会吸收一定量的Ca,提高抗逆性.圆叶乌桕的化学元素特征反映了它对石灰岩生境的适应性较强.     

激素对黑莓‘Kiowa’叶片愈伤组织诱导的影响

以黑莓品种‘Kiowa’无菌苗的叶片为外植体,研究了外源生长调节剂对愈伤组织诱导的影响。结果表明:不同激素种类、浓度及其配比诱导‘Kiowa’的叶片都可以产生愈伤组织,并且诱导率都为100%,但愈伤组织的状态和生长量有显著差异。其中添加2,4-D产生的愈伤组织质量较好,生长素和细胞分裂素组合使用时有抑制愈伤组织诱导的作用;添加1.0 mg/L 2,4-D的MS培养基诱导的愈伤组织多,质地疏松,呈嫩黄色颗粒状。     

新型试管花卉姬松高效再生体系的研究

 以新型试管花卉多肉类植物姬松（Crassula clavata N. E. Brown）为材料进行高效再生体系 的研究。结果表明：以姬松茎尖为外植体的初代培养中,MS 培养基添加IBA 并未诱导出根系生成,而是 直接诱导出丛生芽,在MS + IBA 0.3 mg · L-1 培养基上,由叶片表面诱导出的丛生芽质量最佳;在继代培 养中,最佳培养基为MS + NAA 0.1 mg · L-1 + 6-BA 0.5 mg · L-1,诱导产生大量胚性愈伤组织,且表面有 芽体分化;在彩色培养中,在1/2MS 中添加0.25 mg · L-1 的食用色素亮蓝,观赏效果佳且对植株生长无毒 害。     

不同环境因子对辽东栎种子更新影响的研究进展

植物自然更新过程是一个复杂的生态学过程,它对种群的增殖、扩散、延续和群落稳定及演替具有重要的作用。辽东栎通过种子更新可以维持其种群的持久性与遗传多样性。目前国内外对辽东栎种子更新影响的研究主要是从单一环境因子出发,着重分析某一环境因子对其更新的影响。文章主要通过阅读大量文献的方法,从光照、水分、动物搬运、地表覆盖物、林窗几方面对辽东栎种子更新的影响进行总结,并提出今后该领域的研究建议。     

Effect of the Substrates upon the Regeneration of the Engrafted Cuttings and the Yield of Engrafted Rooted Vines

Engrafted cuttings of the variety Rkaciteli on stocks B?×?R Cober 5BB and R?×?R 101-14, having endured open and covered stratification on different substrates, were planted in a polyethylene glasshouse on four artificial substrates after the postplanting preparation. The complex effect of the stock variety was examined, as well as the effects of the stratification methods and the substrates on the yield of engrafted vines. The characteristics of the regeneration of the engrafted cuttings during the stratification were established. The optimal substrates for stratification of the transplants and the growing of engrafted vines in glasshouses were defined.