Morphological and physiological responses of two coffee progenies to soil water availability

Drought is a major environmental constraint affecting growth and production of coffee. The effects of water supply on growth, biomass allocation, water relations, and gas exchange in two coffee progenies representing drought-tolerant (Siriema) and drought-sensitive (Catucaí) genotypes were compared. They were grown in 12-L pots until 4-months old, when they were submitted to two watering treatments for 60 d: plants receiving either 100% transpired water (control plants) or a fraction (about 40%) of the amount of water transpired by control plants (drought-stressed plants). Under control conditions, Siriema grew faster than Catucaí. Regardless of the watering regimes and progenies, relative growth rate (RGR) was positively correlated both with net assimilation rate (NAR) and long-term water-use efficiency (WUE), but not with differences in biomass allocation. Both progenies responded to drought stress through (i) similar decreases in both RGR and NAR with marginal, if any, changes in allocation; (ii) decreases in leaf water potential, which occurred to a greater extent in Catucaí than in Siriema, even though they have showed similar abilities to adjust osmotically and elastically; (iii) similar reductions in net photosynthesis due mainly to nonstomatal factors; and (iv) decreases in transpiration rate coupled with increased long-term WUE. However, the lower transpiration rate and the higher long-term WUE as found in Siriema relative to Catucaí under control conditions persisted under drought conditions. Overall, the major differences between these progenies were largely associated with differences in plant water use, which was likely related to the improved water status of Siriema. The possible implications of selecting coffee genotypes for high WUE are discussed.     

拟单性木兰不同季节断根和剪枝后蒸腾和光合特性的变化

在2005年春季、夏季和秋季,对10a生拟单性木兰(Parakmeriaomeiensis)进行断根和剪枝处理,模拟移栽,用LICOR-6400测定了植株叶片的蒸腾速率、光合速率等生理指标,探讨这些生理指标对不同季节移栽成活率的影响。结果表明,春季处理后叶片能迅速关闭部分气孔,蒸腾速率和光合速率都减小,两者最低时约为对照的60%,生理机能的减弱有利于维持地上、地下部分的平衡,因而最有利于植株成活。夏季处理后叶片气孔导度显著增加,光合速率和蒸腾速率也随之增大,最高时约为对照的2倍左右,此时,若主要依靠剪枝来降低水分消耗,很难保证水分代谢平衡,移栽成活率低。秋季处理后植株叶片气孔导度高于对照,光合速率和蒸腾速率也增加,但增加幅度相对夏季较小,前期最高约增加40%,此时移栽可以通过适当的剪枝和增加土壤水分含量等措施提高成活率。可见,与水分相关的生理机能的调节机制,决定了移栽后的成活水平,即处理后能迅速调节自身生理机能、减少水分消耗的植株,成活率就高,反之就低。     

银杏的蒸腾特性及其对遮荫的响应

在夏季晴天土壤供水充足的条件下,生长在庐山山地上的银杏（ＧｉｎｋｇｏｂｉｌｏｂａＬ．）,其向阳叶片蒸腾速率的日变化属午后高峰型,日平均蒸腾速率约为１．８６ｍｍｏｌＨ２Ｏ·ｍ－２·ｓ－１,最大蒸腾速率约为３．８ｍｍｏｌＨ２Ｏ·ｍ－２·ｓ－１;其水分利用率日平均约为２．９ｍｍｏｌＣＯ２·ｍｏｌ－１Ｈ２Ｏ,最高可达８．６ｍｍｏｌＣＯ２·ｍｏｌ－１Ｈ２Ｏ。银杏叶片的蒸腾速率、气孔阻力和水分利用率等对遮荫的响应在一天的不同时间各不相同,表明了银杏的生长对当地变化的光照条件是适应的。气温、光合有效辐射和气孔阻力等因素对银杏蒸腾速率的影响显著。     

Seasonal patterns of gas exchange,water relations and growth of it Roupala montana,an evergreen savanna species

Roupala montana is an evergreen species widespread in the seasonal savannas of the central plains of Brazil. I examined the degree of coupling of photosynthetic gas-exchange characteristics, water relations and growth responses of R. montana with regard to seasonal changes in soil water availability. Despite a rainless period of over three months soil water potential at 60 cm depth reached values of only about -1.0 MPa, while pre-dawn leaf water potential (^l) reached about -0.4 MPa by the end of the three-month drought. Thus, R. montana had access to deep soil water in the dry period, but pre-dawn ^l did not reach the high wet season values of -0.2 MPa. Most of the shoot growth was concluded in the onset of the rainy season. Although some individual branches might have shown some extension thereafter, most of them remained inactive during the rest of the rainy season and the subsequent dry season. New leaf production was also restricted to the first part of the wet period. R. montana remained evergreen in the dry season, but there was a 27% decrease in the number of leaves and herbivory removed about 16% of the leaf area still present in the plant. CO₂-exchange rates of these leaves reached only ca. 55% of the maximum rainy season values of 14 µmol m^-2 s^-1. Thus, the estimated potential daily carbon gain was about 34% of the maximum by the end of the dry period. These values will be even lower, if we considered the decrease in photosynthetic rates that occurred around midday. These reductions in photosynthetic rates as a result of partial stomatal closure were measured both in the wet and dry season and they were related to increases in the evaporative demand of the atmosphere. In conclusion, the combined effect of herbivory, leaf loss and reductions in photosynthetic rates limited plant productivity in the dry season.     

不同时期毛乌素沙区主要植物种光合作用和蒸腾作用的变化

 采用LI—6000便携式光合分析系统对毛乌素沙区主要植物种油蒿、中间锦鸡儿、旱柳进行了不同时期光合作用,蒸腾作用日进程的测定,并同步测定有效光辐射、空气相对湿度、叶温、气温、胞间CO2浓度、气孔阻力、叶片水势及土壤水势等因子;结果表明：不同时期、不同植物种其光合、蒸腾特征各异;植物的光合、蒸腾与环境因子和植物内部因子之间有密切关系,其中有效光辐射是影响光合作用、蒸腾作用诸因子中的主导因子,而气孔阻力变化则在调节光合和蒸腾中起着重要作用;不同植物种间气孔对环境条件变化的响应程度不同,以中间锦鸡儿最为灵敏;3种植物的水分利用效率表明,中间锦鸡儿的水分利用效率较油蒿、旱柳为高。     

田间不同条件下玉米叶片的气孔阻力及与光合、蒸腾作用的关系

以玉米17个自交系和10个杂交种为试材,在田间条件下研究了不同光强、不同叶位、不同生育期、不同源库比例和株间差异状态下的气孔阻力及其与光合(PH)、蒸腾(TR)和叶片水分利用效率(WUE)的关系,结果表明,不同自交系之间RS具有显著的差异,相差最大可达2.3倍以上;光照条件变弱、穗叶位差增加、生育期推延和源/库比例改变等均可引起RS值的增加;在各种情况下导致RS变化的同时也引起TR和PH产生相应的变化,RS与TR、PH表现出显著或极显著的负相关,且相关系数r_RS-TR>r_RS-PH;RS与WUE的相关关系在不同的条件下表现出不稳定性.     

模拟酸雨对柚木幼苗生长、光合与水分利用的影响

模拟pH6.5(对照)、4.5和2.5三个酸雨梯度,研究其对1a生组培柚木(TectonagrandisL.f.)幼苗生长、光合与水分利用的影响。结果表明,尽管不同处理间的各项生理指标差异不明显,但模拟酸雨对柚木形态构件参数造成较严重的影响。pH4.5和pH2.5处理组柚木基径(D)和树高(H)增长明显下降,使得D2H下降更加显著;不同处理下柚木叶片净光合速率(Pn)和蒸腾速率(E)日变化趋于一致,气孔导度(gs)日变化与对应的叶片净光合速率日变化十分相似,同时,对照与两个处理的Pn与gs之间都表现正相关(p<0.01),且在pH4.5处理表现更为显著,但是对照和两个处理的E与gs的线性关系不显著;pH4.5和2.5处理的水分利用效率(WUE)日变化趋于一致;对照胞间CO2浓度与大气CO2浓度比(Ci/Ca)均值最低,表明对照柚木对CO2利用最有效。     

鹤山人工马占相思林水分生态研究

 通过对马占相思叶片的蒸腾速率、气孔导度及其相应环境因子的测定,探讨鹤山丘陵人工马占相思林的水分生理生态特征。结果表明：蒸腾速率和气孔导度具有明显的日变化,两者的变化趋势相似,在夏季的日变化曲线呈双峰型,冬季呈单峰型;夏季的蒸腾速率最高,在冬季最低,仅占夏季的27.6％;马占相思林的蒸腾耗水量在旱季和雨季有明显的差异,旱季的蒸腾耗水量占雨季的25.5％,年蒸腾量为1625.1mm,占同期降水量的78.3％;马占相思林的蒸腾量接近热带雨林。     

Evaluation of physiological traits for improving drought tolerance in faba bean (<Emphasis Type="Italic">Vicia faba</Emphasis> L.)

Among grain legumes, faba bean is becoming increasingly popular in European agriculture due to recent economic and environmental interests. Faba bean can be a highly productive crop, but it is sensitive to drought stress and yields can vary considerably from season to season. Understanding the physiological basis of drought tolerance would indicate traits that can be used as indirect selection criteria for the development of cultivars adapted to drought conditions. To assess genotypic variation in physiological traits associated with drought tolerance in faba bean and to determine relationships among these attributes, two pot experiments were established in a growth chamber using genetic materials that had previously been screened for drought response in the field. Nine inbred lines of diverse genetic backgrounds were tested under adequate water supply and limited water conditions. The genotypes showed substantial variation in shoot dry matter, water use, stomatal conductance, leaf temperature, transpiration efficiency, carbon isotope discrimination (Δ¹³C), relative water content (RWC) and osmotic potential, determined at pre-flowering vegetative stage. Moisture deficits decreased water usage and consequently shoot dry matter production. RWC, osmotic potential, stomatal conductance and Δ¹³C were lower, whereas leaf temperature and transpiration efficiency were higher in stressed plants, probably due to restricted transpirational cooling induced by stomatal closure. Furthermore, differences in stomatal conductance, leaf temperature, Δ¹³C and transpiration efficiency characterized genotypes that were physiologically more adapted to water deficit conditions. Correlation analysis also showed relatively strong relationships among these variables under well watered conditions. The drought tolerant genotypes, ILB-938/2 and Melodie showed lower stomatal conductance associated with warmer leaves, whereas higher stomatal conductance and cooler leaves were observed in sensitive lines (332/2/91/015/1 and Aurora/1). The lower value of Δ¹³C coupled with higher transpiration efficiency in ILB-938/2, relative to sensitive lines (Aurora/1 and Condor/3), is indeed a desirable characteristic for water-limited environments. Finally, the results showed that stomatal conductance, leaf temperature and Δ¹³C are promising physiological indicators for drought tolerance in faba bean. These variables could be measured in pot-grown plants at adequate water supply and may serve as indirect selection criteria to pre-screen genotypes.     

淹水时水翁幼苗光合特性与不定根的关系(简报)

淹水引起水翁幼苗净光合速率、气孔导度和蒸腾速率发生变化。淹水５ｄ后,水翁幼苗净光合速率、气孔导度和蒸腾速率慢慢下降。但从淹水第３５天开始,部分水翁幼苗在淹水的茎部产生不定根,有不定根的水翁幼苗的净光合速率、气孔导度和蒸腾速率逐渐提高,到第８０天后维持在较高水平。有不定根的水翁幼苗的净光合速率、气孔导度和蒸腾速率的日进程呈双峰型,回归分析表明,净光合速率与气孔导度呈正相关（ｒ＝０．６９,Ｐ〈０．０５     

木本植物气孔对不同污染类型的反应

植物气孔扩散阻力与环境中颗粒物的污染有密切关系,由此得出的生理指标可用以指示大气中飘尘污染的程度,并筛选对污染物抗性大和消耗水分少的植物种。测定结果表明：不同污染类型区的植物气孔扩散阻力的大小顺序因地区而不同,在天津为冶炼厂(重工业污染区)>水上公园(游览区)>劝业场(商业集中区)>化工厂外(化工污染区) >盘山(清洁区);而在北京是卧佛寺一樱桃沟(游览区)>东单(交通频繁区)>首钢(重工业污染区)。之所以产生上述差异的原因除了京津两市的工业污染外,还与某些人为活动有关,如重工业污染区飘尘污染严重,植物气孔扩散阻力增大,但首钢经常用水冲洗叶子,其阻力值反小;公园和商业交通区是游人熙攘地点,极易引起地面扬尘,其气孔阻力反映了相似的结果。 研究结果还阐明：随着飘尘的增加,植物气孔扩散阻力增大,蒸腾率速相应的变小。     

茶树蒸腾特性的研究

茶树蒸腾速率和气孔导度因品种、叶位不同而异．抗旱性强的品种具有低的气孔导度;鱼叶的蒸腾速率和气孔导度接近或高于真叶．茶树叶片蒸腾速率夏、秋季最高,春季次之,冬季最低．在晴天,茶树蒸腾速率和气孔导度的日变化呈单峰型,以中午前后最高;其日变化与光量子通量密度、叶温、蒸汽压亏缺等因子显著相关;光量子通量密度对蒸腾速率和气孔导度影响较明显．     

大田玉米、高粱、芝麻、豇豆叶片水势、蒸腾速率、气孔阻力对环境因素的反应

本文研究了田间生长的玉米、高梁、芝麻、豇豆在不同土壤供水条件下,叶水势、气孔阻力、蒸腾速率日变化及其与环境因素的关系。结果表明,四种作物气孔开闭与光强密切相关:夜间气孔关闭,rs高;白天气孔开放,rs低。ψ_(WL)、TR与环境因素(气温、RH、ψ_(WV)、光强等)密切相关,它们之间的相关系数(在0.05和0.01水平)显著。四种作物ψ_(WL)日节奏为“正弦曲线”状,13:00—15:00小时ψ_(WL)最低,黎明前最高。中午ψ_(WV)和土壤含水量愈低。ψ_(ML)愈低。四种作物TR在早晨逐斩增高,13:00—15:00小时最强;傍晚前又降低;夜间TR最低。干旱植株ψ_(WL)、TR低于灌水植株,而rs高于灌水植株。     

田间不同条件下玉米叶片的气孔阻力及与光合,蒸腾作用的关系

以玉米 1 7个自交系和 1 0个杂交种为试材 ,在田间条件下研究了不同光强、不同叶位、不同生育期、不同源库比例和株间差异状态下的气孔阻力及其与光合 (PH)、蒸腾(TR)和叶片水分利用效率 (WUE)的关系 ,结果表明 ,不同自交系之间RS具有显著的差异 ,相差最大可达 2 .3倍以上 ;光照条件变弱、穗叶位差增加、生育期推延和源 /库比例改变等均可引起RS值的增加 ;在各种情况下导致RS变化的同时也引起TR和PH产生相应的变化 ,RS与TR、PH表现出显著或极显著的负相关 ,且相关系数rRS TR>rRS PH;RS与WUE的相关关系在不同的条件下表现出不稳定性     

边界层阻力在叶片气体交换过程中的作用

作者对现有的气体交换法的叶室作了改进。从实验上检验了作者根据电学类比分析和模拟检验得到的结论：在已有的气体交换测定装置中,空气流速不变,叶片的边界层导度也固定不变,所得到的结论用于边界层导度变化的情形时,会造成比较大的误差。现加一障碍物使得流过叶片的风速减小,从而改变叶片的边界层导度。通过测量在不同边界层导度下同一叶片的光强曲线可以考察不同边界层导度下的气孔导度、光合速率、蒸腾速率以及它们之间的相互关系。实验结果与作者以前的电学类比分析和模拟得到的结论是基本一致的     

Pulvinus activity,leaf movement and leaf water-use efficiency of bush bean (<Emphasis Type=Italic>Phaseplus vulgaris</Emphasis> L.) in a hot environment

Pulvinus activity of Phaseolus species in response to environmental stimuli plays an essential role in heliotropic leaf movement. The aims of this study were to monitor the continuous daily pulvinus movement and pulvinus temperature, and to evaluate the effects of leaf movements, on a hot day, on instantaneous leaf water-use efficiency (WUE_i), leaf gas exchange, and leaf temperature. Potted plants of Phaseolus vulgaris L. var. Provider were grown in Chicot sandy loam soil under well-watered conditions in a greenhouse. When the second trifoliate leaf was completely extended, one plant was selected to measure pulvinus movement using a beta-ray gauging (BRG) meter with a point source of thallium-204 (²⁰⁴Tl). Leaf gas exchange measurements took place on similar leaflets of three plants at an air temperature interval of 33–42°C by a steady-state LI-6200 photosynthesis system. A copper-constantan thermocouple was used to monitor pulvinus temperature. Pulvinus bending followed the daily diurnal rhythm. Significant correlations were found between the leaf-incident angle and the stomatal conductance (R ² = 0.54; P < 0.01), and photosynthesis rate (R ² = 0.84; P < 0.01). With a reduction in leaf-incidence angle and increase in air temperature, WUE_i was reduced. During the measurements, leaf temperature remained below air temperature and was a significant function of air temperature (r = 0.92; P < 0.01). In conclusion, pulvinus bending followed both light intensity and air temperature and influenced leaf gas exchange.     

七子花苗期光合生理生态特性研究

对七子花苗期的光合生理生态特性进行了研究,结果表明：（1）净光合速度,蒸腾速率的日进程曲线呈“双峰”型,胞间CO2浓度的日进程基本与净光合速率相反,中午胞间CO2浓度增高表明净光合速率午间 要受非气孔限制因素的影响,暗呼吸速率日进程呈单峰曲线,中午阳高。气孔阻力的变化规律与蒸腾速率基本相反。光能利用效率以上午7：00为最高,中午最低,以后又逐渐上升。水分利用效率以7：00最高,10：00－16：00较低。（2）一天分时段光响应试验表明,饱和光强 表观量子产额上午最高,中午最低,下午有所上升。上午和下午光补 点比较接近,中午增高一倍多。不同时段遮光都使得蒸腾速率下降,以下进下降幅度最大,但使气孔阻力升高,下午增加幅度最大。（3）上午羧化效率最高,中午最低,下午稍有上升,而CO2补偿点中午最高。