黄瓜幼苗干物质积累、膨压及光合速率对铵态氮和硝态氮的响应

采用溶液培养方法,研究了氮素形态及水平对黄瓜干物质积累、膨压及光合速率的影响。结果表明,同一氮素水平时,NO3--N处理黄瓜干物质重量、叶片面积、叶片含水量、水势、膨压等均高于NH4+-N处理。低水平NH4+-N(5mmol/L)对黄瓜光合速率影响不大,甚至高于同水平NO3--N处理的,叶片面积稍有减小;高水平NH4+-N不仅显著抑制黄瓜干物质的积累,叶片面积仅是同水平NO3--N处理的12.7%,最小光合速率（Pn）为CO2 1.6mol/（m2·s）,仅为同水平NO3--N处理的10%左右。NH4+-N处理引起黄瓜叶片面积的减小与叶片膨压降低相关性较大,相关系数为0.98;膨压与叶片水势直接相关,而渗透势对此影响不大。高水平NO3--N对黄瓜产生了渗透胁迫,抑制黄瓜生长,表现在渗透调节物质的大量积累。不同黄瓜品种对氮素形态及水平响应差异较大,所有处理中新泰密刺长势均好于吉尼罗。低水平的NH4+-N对黄瓜干物质的积累影响不大,高水平则明显抑制其生长。说明高浓度铵态氮对植物产生了毒害,而高浓度的硝态氮则是渗透胁迫。     

北方主要造林树种耐旱机理及其分类模型的研究──叶保水力及维持膨压

从叶保水力及维持膨压两个方面，对２１个不同耐旱机理树种的耐旱生理特点进行了比较研究。结果表明：高水势延迟脱水耐旱树种（油松、樟子松、长白松、华山松、白皮松、火炬树、二白杨、华北落叶松）具有很强的保水力和维持膨压的能力；低水势忍耐脱水耐旱树种（山杏、山桃、栾树、文冠果、花椒、白榆、新疆杨、杜仲、红柳、沙枣、毛条、胡杨）则表现出较弱的保水力和维持膨压的能力。     

Comparative monitoring of temporal and spatial changes in tree water status using the non-invasive leaf patch clamp pressure probe and the pressure bomb

Real-time monitoring of plant water status under field conditions remains difficult to quantify. Here we give evidence that the magnetic-based leaf patch clamp pressure (LPCP) probe is a non-invasive and online-measuring method that can elucidate short- and long-term temporal and spatial dynamics of leaf water status of trees with high precision in real time. Measurements were controlled remotely by telemetry and data transfer to the Internet. Concomitant measurements using the pressure chamber technique (frequently applied for leaf water status monitoring) showed that both techniques yield in principle the same results despite of the high sampling variability of the pressure chamber data. There was a very good correlation between the output pressure signals of the LPCP probe and the balancing pressure values (on average r² = 0.90 ± 0.05; n = 8), i.e. the external pressure at which water appears at the cut end of a leaf under pressure chamber conditions. Simultaneously performed direct measurements of leaf cell turgor pressure using the well-established cell turgor pressure probe technique evidenced that both techniques measure relative changes in leaf turgor pressure. The output pressure signals of the LPCP probe and the balancing pressure values were inversely correlated to turgor pressure. Consistent with this, the balancing pressure values and the cell turgor pressure values could be fitted quite well by the same firm theoretical backing derived recently for the LPCP probe (Zimmermann et al., 2008). This finding suggests that use of the LPCP probe technique in agricultural water management can be built up on the knowledge accumulated on spot leaf or stem water potential measurements.     

水果细胞的内压和应力与变形之间关系的研究

水果或蔬菜在收获、运输、加工和贮藏的各个环节中都要不同程度地受到机械损伤,并造成大量损失。多数机械损伤都与外载引起的细胞损伤紧密相关。为此,把细胞模拟成充满不可压缩液体的、封闭的圆柱形薄壁结构,分析了水果细胞在外载作用下,细胞内压和细胞壁应力与主伸长比之间的关系,为探讨水果、蔬菜在外载作用下的损伤机理提供理论依据。     

几种果树水分生理指标的比较研究

以盆栽２年生苹果、杏、桃和葡萄为试材，研究了水分逆境对果树水分关系的形响及差异。从正常灌水（田间持水量８０％）所测定的萎蔫点相对合水量（ＲＷＣｐ）、萎蔫点水势（ψｗｐ）和总体原初渗透压（ψｚ０）判断， ４种果树抗旱性的顺序是：杏、桃＞苹果＞葡萄。干旱下测定的 ３种参量所反映的结果与上述一致。４种果树正常灌水处理弹性大小的顺序是：苹果＞杏＞葡萄＞桃，最大体积弹性模量（Ｅｖ０）分别是：３８．７、４４．９、５１．７、５５．６ＭＰａ。干旱条件下使苹果、杏弹性变差，葡萄、桃弹性增大。Ｅｖ０分别是：７１．７６、９０．６７、５４．０８和４０．４８ＭＰａ，说明ＣＫ弹性好坏不能反映对长期干旱的适应性。弹性系数与膨压（ψｐ）成显著直线正相关，说明弹性越好（Ｅｖ０越小），维持ψｐ能力越强，有利于气孔开张、维持光合。Ｅｖ０小者（苹果、杏）， Ｅｖ０随ＲＷＣ降低而缓慢降低，细胞伸缩范围大。 水分协迫下，苹果、各具有明显的渗透调节作用，苹果ψｗｐ和ψｚ０分别比ＣＫ下降０．５和０．４ＭＰａ，杏分别下降 ０． ６１和 ０． ５９ＭＰａ，葡萄只具有微弱的渗透调节能力，ψｗｐ和ψｚ０分别下降 ０． １６和 ０． １３ＭＰａ，桃无渗透调节能力。多一位处理使     

土壤干旱胁迫下苹果叶片膨压维持对光合速率及生长的影响

以新红星和红富士苹果叶片为试材,利用P－V分析技术研究了在水分胁迫条件下叶片细胞的膨压维持方式以及细胞膨压维持对苹果叶片的光合速率、叶面积及干物质积累（叶片干重）等生理特性的效应。结果表明,两品种叶片在不同水分胁迫条件下细胞膨压维持能力不同,中度水分胁迫下膨压维持是以渗透调节和弹性调节并存,具有膨压维持能力,严重水分胁迫下渗透调节和弹性调节均消失,膨压维持能力丧失。细胞膨压的维持能够减少叶片叶绿素的破坏,维持干旱条件下（中度水分胁迫）的光合作用较正常进行,叶片正常生长及干物质积累。     

Yield and Osmotic Adjustment Capacity of Barley Under Terminal Water-Stress Conditions

This paper reports the influence of the osmotic adjustment capacity and turgor potential (TP) on tolerance to drought in 12 cultivated genotypes, six breeding lines and six cultivars of barley (Hordeum vulgare L.) under terminal water‐stress conditions. When the crops reached the flag leaf stage, half of the experimental plots in which they were grown were submitted to water stress treatment and the remainder maintained under optimal irrigation conditions. Differences were seen in the osmotic adjustment, relative water content (RWC) and water potential (WP) of the different genotypes. Two of the breeding lines showed the greatest osmotic adjustment capacities, maintaining their TPs better than the other genotypes studied. A positive, significant correlation was found between yield and osmotic adjustment capacity, RWC and WP under water‐stress conditions. Osmotic adjustment capacity and TP were linearly related, indicating that as water stress increases osmotic adjustment favours the maintenance of higher TPs. Significant correlations were found between osmotic adjustment capacity and grain filling rate and grain yield. Under conditions of terminal water stress, yield was negatively correlated with the number of days to ear emergence; no correlation was found between osmotic adjustment capacity and earliness. Early ear emergence, a good osmotic adjustment capacity and high RWC values all contributed to yield increases under terminal water‐stress conditions.     

DHN黑色素与玉米大斑病菌附着胞膨压形成的关系

 【目的】探讨玉米大斑病菌胞内DHN黑色素在附着胞膨压产生过程中的作用,明确玉米大斑病菌的侵入机理。【方法】通过诱导玉米大斑病菌附着胞产生,确定附着胞形成的最佳条件,利用溶质排斥技术及incipient-cytorrhysis技术对玉米大斑病菌野生型菌株01-23和黑色素缺失突变体△St3hnr附着胞细胞壁孔径大小和膨压进行测定。【结果】野生型菌株01-23细胞壁孔径范围是2.1—2.7 nm,膨压在5.4 MPa左右;黑色素缺失突变体△St3hnr细胞壁孔径范围是2.7—3.3 nm,膨压在4.1 MPa左右;缺乏黑色素的附着胞不能形成高膨压,丧失了穿透能力。【结论】黑色素层对溶质分子外渗的阻挡作用导致了附着胞高膨压的产生,膨压产生的机械穿透力在玉米大斑病菌穿透基质平面的过程中发挥了重要作用。     

Epicuticular wax content and morphology as related to ethylene and storage performance of ‘Navelate’ orange fruit

The effect of ethylene (2 μL L⁻¹) on total and soft epicuticular wax content and wax morphology has been investigated in mature ‘Navelate’ (Citrus sinensis, L. Osbeck) oranges held under non-stressful environmental conditions (22 °C and constant high relative humidity (90–95% RH)). In addition, the objective of the study was to understand whether the ethylene-induced changes in epicuticular wax might participate in the beneficial effect of ethylene reducing non-chilling peel pitting, by modifying peel water, osmotic or turgor potential, or disease incidence caused by Penicillium digitatum (Pers.:Fr.) Sacc. Ethylene increased total and soft epicuticular wax content in ‘Navelate’ fruit and induced structural changes in surface wax that might be related to the formation of new waxes. Changes in epicuticular wax morphology, but not in its content, might be involved in the protective role of ethylene reducing non-chilling peel pitting, although the beneficial effect of the hormone is not related to water stress. Cell water and turgor potentials in freshly harvested fruit and fruit stored in air under non-stressful conditions suggest that water stress is not a limiting factor leading to the development of this physiological disorder. In addition, the results indicated that formation of new waxes in fruit treated with ethylene may partially cover stomata, cracks or areas lacking wax occurring in stored fruit and is likely to improve physical barriers to P. digitatum penetration.     

Osmoregulative capacity in birdseed millet under conditions of water stress. I. Variation in Setaria italica and Panicum miliaceum

Experiments involving 14 accessions of Panicum miliaceum L. (Proso millet) and 11 accessions of Setaria italicaL. (Foxtail millet) have demonstrated variability in the degree of osmoregulative capacity among these accessions. Birdseed millet is generally claimed to be sensitive to drought stress, apparently because of a shallow root system. Accessions with high osmoregulative capacity demonstrate at least some drought tolerance. Osmoregulative capacity was measured on flag leaves of headed millet plants in pots undergoing water stress in a controlled environment chamber. Osmoregulative capacity was determined from the relationship between osmotic potential and leaf water potential; and the logarithmic relationship between osmotic potential and relative water content. The group of accessions of S. italica showed an overall level of osmoregulative capacity which was greater than that observed for the group of P. miliaceum accessions. Four accessions of S. italica(108042, 108463, 108541 and 108564) and one accession of P. miliaceum (108104)demonstrated high osmoregulative capacity. Differences of 1.05 MPa or more between observed and estimated osmotic potential were found at relative water contents of80 % among these accessions. The extent of osmoregulative capacity was associated with osmotic potential at full turgor and the rate of decline in osmotic potential as leaf water potential declined. This revised version was published online in August 2006 with corrections to the Cover Date.