The yield pattern considering the distance to flow accumulation lines

Precision agriculture techniques imply a spatial management of fields and to do so a good understanding of the spatial and temporal variability of yield is needed. Average yield data from seven irrigated maize fields were used to study the yield pattern considering the distance of plants to flow accumulation lines. It was found that there is a significant correlation between average yield and distance to flow accumulation lines (DFL). This correlation is best represented by a polynomial function. The most common shape of the yield pattern curve considering the distance to flow accumulation lines shows that there is an increase in average yield with DFL from 0 to 12.5–17.5 m. Near the flow lines the average yield presents lower values due to drainage problems causing plant growth problems. It was also observed higher yield variability near the flow lines. For higher distances from the flow lines there is a continuous decrease in average yield due to less water availability and other variations of soil properties.     

Control of postharvest diseases on citrus fruit by preharvest application of the biocontrol agent Pantoea agglomerans CPA-2: Part I. Study of different formulation strategies to improve survival of cells in unfavourable environmental conditions

The objective in the present study was to investigate the survival and effectiveness of different biological agent Pantoea agglomerans formulations against Penicillium spp. with different preharvest treatments. Results indicated a high sensitivity of non-adapted and osmotic-adapted P. agglomerans cells to environmental conditions in the field, resulting in preharvest treatments which were ineffective against Penicillium spp. In the second part of this study, dry conditions and solar radiation were identified as important environmental conditions that seriously affect populations of P. agglomerans cells. Different formulation strategies were tested in order to improve the resistance of cells to unfavourable environmental conditions. Osmotic-adapted P. agglomerans cells in the presence of 25 g L⁻¹ of NaCl in the production medium [osmotic-adapted treatment (P25)] or at water activities (a_w) of 0.98 [osmotic-adapted treatment (P98)] had higher survival rates than non-adapted cells, when these cells were sprayed on oranges and stored in hermetically sealed chambers at a low RH of 43%. Among seven additives tested, the presence of 5% Fungicover in the bacterial suspension improved adherence and persistence of P. agglomerans cells on oranges exposed to unfavourable conditions. Therefore, while P. agglomerans cells sprayed alone had log values of 0.5 CFU cm⁻², in combination with Fungicover the population level of P. agglomerans cells reached log values of 5 and 4.2 CFU cm⁻², at 0 and 24 h after application. Lyophilised cells showed greater resistance to unfavourable environmental conditions than fresh cells. The present study has demonstrated that the formulation improvement can provide better performance of biocontrol agents under environmental conditions non-conducive for growth and survival.     

葡萄采后致腐病原菌鉴定及侵染规律

以红地球,巨峰,玫瑰香,马奶葡萄为试材,对鲜食葡萄采后腐烂病原菌进行了分离、纯化、致病力测定和鉴定及其侵染规律的研究.研究表明,引起葡萄采后腐烂的病原茵主要有灰霉,黑曲霉,青霉,根霉,链格胞和拟茎点霉属6个属.其中黑曲霉和根霉为高温致腐菌,灰霉菌和链格胞为低温致腐菌,根霉和黑曲霉只有在有伤时才可以侵入,在不同品种上或同一品种上的不同部位主要致腐菌各不相同.     

基于阻抗仪和ERT技术的红松内部腐朽定量检测

为了定量表征红松活立木内部腐朽情况,在黑龙江省五营国家森林公园选取了15棵有不同腐朽程度的红松,应用Resistograph树木微钻阻抗仪和PiCUS Treetronic树木电阻断层成像仪得到南北向与东西向的微钻阻力变化和同样高度上的截面电阻率分布图,对比分析阻抗仪测量方向上的电阻率变化和微钻阻力变化。用树木生长锥在样木的测量位置附近各取南北向与东西向的木芯,将其带回实验室测量质量损失率。将微钻阻力的下降幅度定义为阻力损失,对阻力损失和木芯质量损失率进行回归分析。还用腐朽和健康部分的电阻率均值定义了电阻率的异常程度, 并对其和阻力损失进行了回归分析。以阻抗仪为基准在电阻率分布图上对腐朽部位定位,应用监督分类的方法在图上将腐朽与健康部分区分出来,并计算腐朽面积所占比例。然后用最小二乘法将算得的比例与木芯质量损失率作回归分析。结果表明:平均阻力损失与木芯质量损失率之间存在显著的线性相关关系,阻抗仪可以较准确地表征一维直线上的腐朽情况;微钻阻力变化曲线上发生阻力值明显下降的位置对应的电阻率也会发生明显变化,阻力损失值和电阻率异常程度存在显著指数关系,还能推断出电阻断层成像检测对于轻度腐朽更加敏感,而阻抗仪检测对较严重的腐朽更加敏感;联合阻抗仪和电阻断层成像技术能够确定腐朽的位置和面积,得到的腐朽面积所占比例与木芯质量损失率有显著线性相关关系。      

涂料与防腐剂复配处理木材的耐腐性能研究

文章以马尾松、尾叶桉、马占相思和南洋楹4种木材为研究对象,采用KJQ、TRQ、WAQ 3种涂料与防腐剂复配处理木材,研究复配涂料对木材耐腐性能的影响。结果表明KJQ复配涂料处理对提高马尾松的耐腐性能较其它2种涂料好。经KJQ复配涂料处理后,马尾松、尾叶桉、马占相思和南洋楹木材的耐腐性能由原来的稍耐腐等级提高到强耐腐等级,其中KJQ涂料与DDAC、IPBC和SGB 3种防腐剂活性成分复配后的处理材耐腐性能较好。     

小兴安岭4树种健康材和腐朽材结晶度的试验

为了对进一步研究纤维的超分子结构及木材的宏观特性提供基础数据,利用X射线衍射法分别测量了白桦(Betula platyphylla)、云杉(Picea koraiensis)、落叶松(Larix gmelinii)和杨树(Poplar)健康材和腐朽材的结晶度。对X射线衍射仪测量的结果进行计算得出:白桦健康和腐朽边材的结晶度分别是43.36%和31.60%;云杉健康和腐朽边材的结晶度分别是41.90%和29.04%;落叶松健康和腐朽边材的结晶度分别是53.59%和40.20%;杨树健康和腐朽边材的结晶度分别是70.26%和48.29%。结果表明,同一树种,腐朽材与健康材相比,结晶构造没有发生变化,但结晶度下降,说明腐朽破坏了纤维结晶区的结晶程度。     

制冷贮藏温度对锦橙的影响

以锦橙为材料,研究不同制冷温度对贮藏效果和锦橙品质的影响。结果表明,温度明显影响着锦橙的腐烂率和褐斑病率,温度6～8℃下贮藏150d锦橙的腐烂率和褐斑病率最低,分别为5.40%和5.41%;温度是影响失质量率的重要因素,制冷贮藏的失质量率低于通风贮藏;温度是影响锦橙果实呼吸代谢的重要因素,果实的呼吸强度随温度的降低而明显降低;果实有机酸含量随温度降低而明显提高,总糖含量的变化规律与有机酸基本相同;低温贮藏也可降低VC、可溶性固形物的损耗;贮藏温度过高,病菌性腐烂率高,品质下降快,而温度过低则产生冷害型腐烂,果皮不能正常转色,认为锦橙长期贮藏的适宜温度为6～8℃。     

浅谈冷凉地区水稻不同群体与产量的关系

为探讨在一般高产栽培管理条件下,水稻不同群体与产量的关系,为生产上推广合理稀植提供科学依据,新宾满族自治县农业技术推广中心进行了不同插秧行距、不同插秧穴距、不同插秧苗数的复因子试验。通过对冷凉地区水稻不同群体与产量关系的研究,结果表明:插秧苗数、穴数、行距对水稻产量的影响不大;插秧的穴距对水稻产量的影响最大,中下等地力应以13.3～16.5 cm为主,肥沃地块应以20 cm为主。     

秸秆复混肥及其对小麦生长发育的影响

将作物秸秆采用０．５ＭＰａ以上的蒸汽压力处理使其在２０ｍｉｎ内腐熟,加入适量比例化肥挤压造粒,制成秸秆复混肥,该肥料含秸秆物质４０％以上,氮、磷、钾含量分别为７．８６％、４．９７％和１４．７７％。田间小麦应用试验表明,秸秆物质对提高肥料利用率,提高作物产量有明显效果。进一步研究还发现,腐熟秸秆与化肥的复混使用可以获得较高的经济效益,其产投比远远高于磷酸二铵和其它普通复混肥。     

完达山林区柞树林病害与主要林分因子的关系

本文通过对完达山林区柞树林病害的调查,掌握了柞树林的主要病害,通过调查研究柞树立木腐朽和林木组成、林分类型的关系以及对经济材的影响。