Effects of irrigation strategies and soils on field-grown potatoes: Gas exchange and xylem [ABA]

Gas exchange was measured in potatoes (cv. Folva) grown in lysimeters (4.32 m²) in coarse sand, loamy sand, and sandy loam and subjected to full (FI), deficit (DI), and partial root-zone drying (PRD) irrigation strategies. PRD and DI as water-saving irrigation treatments received 65% of FI and started after tuber bulking and lasted for six weeks until final harvest. Midday photosynthesis rate (A_n) and stomatal conductance (g_s) of fully irrigated (FI) plants were lowest in coarse sand and mean A_n of diurnal measurements in FI, PRD and DI tended to be lower in this soil as compared with the loamy sand and sandy loam. The results revealed that diurnal values of A_n and g_s in PRD and DI were consistently lower than FI without reaching significant differences in accordance with findings that xylem [ABA] in PRD was significantly higher than FI, and tended to be higher than in DI. Diurnal measurements showed that A_n reached peak values during mid-morning and midday, while g_s were highest during the morning. Intrinsic water use efficiency (A_n/g_s) correlated linearly well with the leaf to air vapor pressure deficit (VPD) and the slope of the line revealed the rate of A_n/g_s increase per each kPa increase in VPD, i.e. approximately 10 μmol mol⁻¹. Transpiration efficiency (A_n/T) of PRD was higher than DI, which shows slightly better efficient water use than DI. The slope of the linear relationship between transpiration efficiency and VPD decreased from −2.03 to −1.04 during the time course of the growing season, indicating the negative effect of leaf ageing on photosynthesis and thus on plant water use efficiency. This fact shows the possibility to save water during last growth stages through applying water-saving irrigations without much effect on transpiration efficiency.     

秸秆预处理中木质纤维物质含量测定方法的研究进展

对国内外主要应用的木质纤维物质的测定方法进行了综述,归纳了各方法的特点与应用情况,并对生物质能源领域内木质纤维物质分析方法的发展方向进行了展望。     

收获期猕猴桃树体钙素营养分布研究

[目的]研究收获期猕猴桃树各器官的生物量、钙含量和钙累积量。[方法]钙含量用HNO3-HClO4消解后用等离子光谱仪测定,钙累积量为钙含量与各器官干重的乘积。[结果]收获期猕猴桃各器官钙含量差异明显,表现为：叶〉根〉茎〉果实,细根高于粗根,老茎大于幼茎;皮层钙含量远高于木质部。在木质部中,根钙含量大于茎;在皮层,根大于1年生枝和2年生枝,小于主干和多年生枝。猕猴桃整株钙累积量为127．36g,根〉茎〉叶〉果实,分别为49,29、43．12、23．30和11．65g,分别占整株钙累积量的38．64％、33．80％、18．26％和9．13％。猕猴桃树整株木质部和皮层生物量分别为4．79kg和2．65kg,分别占树体总生物量的33．45％和18．51％。皮层钙累积量为57．49g,占树体总钙累积量的45．14％,而木质部钙累积量只有11．83g,仅占树体总钙累积量的9．29％,不到皮层的1／4。[结论]该研究初步探索了钙素在猕猴桃树体的分布情况,具有一定的理论和买践意义。     

木本植物木质部栓塞的形成和修复的几点补充

对木质部栓塞的变化规律、不同的因素对栓塞的影响、栓塞的修复现象以及栓塞的修复机理进行了论述,在对以前的相关综述的基础上进行相应的补充。     

Causes of defoliation and low survival rate of grafted sweet pepper plants

We investigated the cause of defoliation in sweet pepper (Capsicum annuum L.) plants after grafting. Grafted plants of old-stage sweet pepper showed a higher defoliation rate than young-stage grafted plants. Old-stage grafted plants had lower stomatal resistance and water potential than young-stage plants, and showed poorly developed xylem connections at the graft site. Foliar application of abscisic acid (ABA) to the grafted plants increased stomatal resistance and water potential, decreased the defoliation rate, and promoted graft take among old-stage plants. Our results indicated that low stomatal resistance under low humidity induces water stress, defoliation, and low survival rate in old-stage grafted sweet pepper plants. ABA treatment increased stomatal resistance, water potential, and survival rate, and decreased the defoliation rate among old-stage sweet pepper plants.     

ALA改变了油菜幼苗体内ABA的含量

[目的]本文的目的是为了揭示ALA处理对冬油菜（Brassica napus L.）幼苗生长的影响及作用机理。[方法]采用营养液培养的方法研究ALA溶液浸种对中双9号油菜幼苗生长及体内ABA含量的影响。实验设置4个处理,分别用0、25、50和75mg/LALA（CK、A1、A2和A3）溶液浸种6h。[结果]除了A3处理使油菜幼苗干重轻微降低之外,ALA浸种使油菜幼苗（根系和地上部）干重、净光合速率、蒸腾速率和气孔导度较对照显著增加。与对照相比,ALA浸种使油菜幼苗体内和木质部伤流液中ABA含量出现不同程度的增加。[结论]提高体内ABA含量可能是ALA浸种处理促进冬油菜幼苗在冬前低温阶段生长的主要原因。     

干旱胁迫下玉米木质部汁液pH和ABA含量变化及其与气孔关系

正常水分状态下 ,玉米茎部木质部汁液 pH高于根部 ,ABA浓度高于根部和叶片 ;干旱胁迫条件下 ,根、茎木质部汁液 pH和ABA都有不同程度升高 ,叶片ABA含量最高。用2 0 0 μmol/L外源ABA处理 ,程度不同地提高根、茎和叶片木质部汁液ABA含量 ,但不能改变器官之间ABA的分布规律 ,却能诱导气孔关闭。不同浓度外源 pH溶液处理植株 ,木质部汁液 pH、蒸腾速率和气孔导度、木质部汁液ABA浓度变化表现出高度一致性。联系他人的研究结果推测 :干旱胁迫后 pH升高很可能通过改变组织和器官之间ABA含量比例 ,使叶片ABA达到足够浓度 ,从而调节气孔关闭 ,调控蒸腾速率。     

嫁接西瓜生长动态及伤流液营养元素含量的研究

对嫁接西瓜和自根西瓜生长动态,根系伤流量及伤流液中营养元素含量进行了研究。结果表明：嫁接西瓜根系发育早,生长速度快,根冠比高,根系伤流量显著增加,伤流液中ＮＯ＾－３－Ｎ,Ｐ,Ｃａ,Ｍｇ,Ｓ含量显著高于自根西瓜特别是ＮＯ＾－３－Ｎ,伸蔓期和开花期分别比自根植株高１０５．０％和９３．７％。     

黑龙江省主栽杨树品系干部单宁含量与青杨脊虎天牛危害的关系

为了探讨决定杨树抗性的生理因素,测定了不同品系杨树中木质部、韧皮部的单宁含量,并调查了杨树的被害株率与虫口密度,分析了杨树中单宁含量与青杨脊虎天牛危害的关系。结果表明,不同杨树品系间韧皮部单宁含量差异极显著,木质部单宁含量差异不显著;杨树各品系的单宁含量与杨树的被害株率关系不紧密。单宁含量与青杨脊虎天牛虫口密度之间存在比较明显的负相关性。小青杨单宁含量高,但株被害率高,株平均虫口密度低。小黑杨单宁含量较低但不受害,其抗虫机理有待进一步研究。外源施用单宁对青杨脊虎天牛有忌避作用。     

冬小麦叶片气栓塞与叶水势日变化的关系

应用超声波(AE)信号测定技术,对冬小麦叶片木质部气栓塞发生与叶水势(ψl)日变化关系进行了研究。结果表明,AE信号在24 h周期内3个活跃期的出现与ψl变化密切相关。上午第一AE活跃期伴随ψl的下降,傍晚第二AE活跃期对应ψl的恢复,午夜前后的第三活跃期对应夜间ψl的进一步恢复,午夜后土壤和植株水势基本达到平衡后,AE信号终止。AE信号发生量和ψl变化量为非线性关系,表现出水势临界值效应,即ψl达到临界值时,微小的ψl变化会引发AE信号峰值。午后最低叶水势出现前的ψl下降期,ψl临界值起身拔节期平均为-1.08 MPa,孕穗至灌浆期平均为-1.60 MPa。叶水势变化是引发小麦叶片气栓塞发生的直接因素之一。