Arsenic-contaminated soils phytotoxicity studies with sunflower and sorghum

Background, Aim and Scope  Environmental pollution caused by arsenic (As) is a major ecological problem. There has been intense worldwide effort to find As-hyperaccumulating plants that can be used in phytoremediation—the green-plant-assisted removal of chemical pollutants from soils. For phytoremediation, it is natural to prefer cultivated rather than wild plants, because their agriculture is well known. This study was conducted to evaluate the tolerance of common sunflower(Helianthus annuus L.) and sugar sorghum(Sorghum saccharatum Pers.) for soil-As contents of 10–100 mg As kg^-1 soil, with sodium arsenite as a model contaminant. Methods  Plants were grown in a growth chamber for 30 days. Microfield experiments were conducted on experimental plots. To study the phytoremediation effect of the auxins indole-3-acetic acid (IAA) and 2,4-dichlorophenoxyacetic acid (2,4-D), we treated 1- and 3-day-old plant seedlings with water solutions of the auxins (concentrations 10^-5, 10^-7, and 10^-9 g l^-1). The soil and plant-biomass samples were analyzed for total As by using the color reaction of ammonium molybdate with As. Results and Discussion  Phytotoxicity studies showed that 100 mg As kg^-1 soil poisoned sunflower and sorghum growth by 50%. There was a linear correlation between soil-As content and As accumulation in the plants. Laboratory experiments showed that the soil-As content was reduced two- to threefold after sunflower had been grown with 10–100 mg As kg^-1 soil for 30 days. Treatment of sunflower and sorghum seedlings with IAA and 2,4-D at a concentration of 10^-5 g l^-1 in microfield experiments enhanced the phytoremediation two- to fivefold as compared with untreated control plants. The best results were obtained with 3-day-old seedlings. Conclusion, Recommendation and Outlook  (a) Sunflower and sorghum are good candidates to remediate As-polluted soils. (b) Phytoremediation can be improved with IAA or 2,4-D. (c) Mixed cropping of sorghum and sunflower may be another way of improving phytoremediation.     

铵态氮抑制向日葵生长的作用机制初步探讨

采用营养液培养方法,研究了细胞膨压的下降与铵态氮(NH4+-N)抑制向日葵生长的关系。结果表明,与硝态氮(NO3--N)相比,铵态氮明显抑制了向日葵的生长,表现在生物量明显降低,顶部展开叶的叶面积显著下降,地上部和顶部展开叶的含水量下降。同时还发现,虽然铵态氮处理向日葵叶片的渗透势与硝态氮处理间差异不显著,但其水势和膨压明显低于硝态氮处理;铵态氮供应使向日葵最大展开叶中K+,Ca2+,NO3-等离子浓度显著下降。说明细胞膨压的下降是铵态氮导致向日葵生长受阻的主要原因之一。     

NaCl胁迫对向日葵种子萌发的影响

通过对盆栽3个品种向日葵进行3种浓度的中性盐胁迫处理,研究了NaCl胁迫对向日葵种子萌发的影响.结果表明:随着NaCl胁迫强度的增加,各品种出苗时间有所延迟,出苗率下降,幼苗苗高和叶片数等均受到影响,NaCl浓度为0.2 mol/L时严重影响向日葵幼苗生长.在抗氧化保护酶活性变化方面,康地5号POD,CAT活性变化较2603和KWS 203快,而SOD活性上升更明显.     

南疆油葵产量与密度的关系及耐密性研究

作物种植密度与产量密切相关，是农业生产中重要技术因素之一。本试验以杂交油葵G101为材料系统研究了产量与密度的关系。结果表明，单株生物产量、群体生物产量、单盘籽粒产量和群体籽粒产量均随密度的升高呈规律性变化，单株生物产量和群体生物产量分别符合W=1/(a bx)和W=x/(a bx)模式，单盘籽粒产量和群体籽粒产量分别符合W=ae^bx和W=axe^bx模式。株高、千粒重、盘径、茎粗符合Y=a bx方程，秕粒率符合Y=a bx cx^2的模式。试验得出最高群体生物产量为23691．06kg／hm^2和最大群体籽粒产量为3740．00kg／hm^2，最适密度为65759．19株／hm^2。     

葵花秆的热解动力学研究

为使葵花秆得到高效清洁的利用,为生物质热解装置的正确设计提供理论依据,采用热重法在不同升温速率下对葵花秆的热解行为进行了研究。结果表明:葵花秆的热解可分为4个阶段,随着升温速率的提高,主反应区热重曲线和微分热重曲线都向高温方向移动,热解最大速率以及相对应的温度随之提高;Ozawa法计算葵花秆主热解区间的活化能值集中在106·33～180·05kJ·mol-1范围内;Satava机理函数推断法得出葵花秆热解的最可能机理属于19号机理函数-Avrami-Erofeev方程,随机成核和随后生长,反应级数n=3。     

向日葵锈菌单核和双核吸器的超微结构比较研究

观察发现,向日葵锈菌单核吸器和双核吸器存在一系列的差异:(1)单核吸器母细胞隔膜不产生隔膜突,入侵口四周的吸器母细胞壁不局部增厚;(2)单核吸器母细胞在入侵寄主细胞壁时不形成入侵栓;(3)双核吸器由管状的颈部和膨大的吸器体组成,单核吸器呈菌丝状;(4)在双核吸器形成过程中,寄主细胞可分泌胼胝质和产生与侵染有关的管状结构。结果表明向日葵锈菌单核的吸器母细胞和吸器的特异性明显低于双核的吸器母细胞和吸器。     

五种药剂防治油葵白锈病试验初报

试验结果表明:64%杀毒矾WP对油葵白锈病防效较好,其次是72%杜邦克露WP、53%金雷多米尔锰锌WG、72%霜疫必克WP。25%甲霜灵WP对油葵白锈病防效不理想。推荐64%杀毒矾WP600倍、72%杜邦克露WP1000倍等防治油葵白锈病在伊犁河谷区域推广应用。     

内蒙古河套灌区主要粮油作物系数的确定

根据FAO-56作物需水量指南推荐的作物系数计算方法,分别计算内蒙古河套灌区磴口试验站小麦、玉米(覆膜与未覆膜)、油料向日葵3种作物的单、双值作物系数。结果表明,磴口试验站单值作物系数较双值作物系数值计算的ET值偏低,双值作物系数计算的ET值与实测结果更为接近,验证了双值作物系数在河套灌区的适用性。     

不同施肥配比对宁夏盐碱土壤油用向日葵产量的影响

研究了不同施肥配比对宁夏盐碱土壤向日葵产量的影响,建立了一元二次肥料效应函数方程.结果表明:对碱化土壤施氮量达到10.56 kg/667m2时,产量达到最大值183.2 kg/667m2;当施磷量达到5.71 kg/667m2时,产量达到最大值156.9 kg/667m2;最高产量施肥配方氮磷钾配比为10.56∶5.7...     

向日葵菌核病菌的生长发育和侵染循环

向日葵菌核病菌的萌发和子囊盘形成的最适温度是10~25℃,最适土壤相对湿度80%~90%,良好的通气条件。菌核的萌发不需要光,但子囊盘的形成需要一定的散射光。菌核在最适宜的条件下的萌发,子囊盘柄的长度最长不超过8 cm。因此,秋季深翻灭茬,可有效防止第二年菌核病的发生。