Variation in cold hardiness and carbohydrate concentration from dormancy induction to bud burst among provenances of three European oak species

Although cold hardiness is known to be a major determinant of tree species distribution, its dynamics and the factors that regulate it remain poorly understood. Variation in cold hardiness and carbohydrate concentration, from dormancy induction until bud burst, were investigated in populations of two deciduous (Quercus robur L. and Quercus pubescens Willd.) and one evergreen (Quercus ilex L.) European oak. Mean cold hardiness values in January were -56, -45 and -27 degrees C for Q. robur, Q. pubescens and Q. ilex, respectively. Soluble carbohydrate concentrations were closely related to instantaneous cold hardiness, estimated by the electrolyte leakage method, whereas total carbohydrate concentration was related to maximum cold hardiness. Both cold hardiness and carbohydrate concentration showed a close linear relationship with temperatures at the location of the sampled population. Our results show that temporal variation in both the inter- and intraspecific cold hardiness in European oaks can be related to variations in the concentrations of soluble carbohydrates and that these relationships appear to be driven by temperature.     

Effects of elevated CO(2) and temperature on cold hardiness and spring bud burst and growth in Douglas-fir (Pseudotsuga menziesii)

We examined effects of elevated CO(2) and temperature on cold hardiness and bud burst of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) seedlings. Two-year-old seedlings were grown for 2.5 years in semi-closed, sunlit chambers at either ambient or elevated (ambient + ~ 4 degrees C) air temperature in the presence of an ambient or elevated (ambient + ~ 200 ppm) CO(2) concentration. The elevated temperature treatment delayed needle cold hardening in the autumn and slowed dehardening in the spring. At maximum hardiness, trees in the elevated temperature treatment were less hardy by about 7 degrees C than trees in the ambient temperature treatment. In general, trees exposed to elevated CO(2) were slightly less hardy during hardening and dehardening than trees exposed to ambient CO(2). For trees in the elevated temperature treatments, date to 30% burst of branch terminal buds was advanced by about 6 and 15 days in the presence of elevated CO(2) and ambient CO(2), respectively. After bud burst started, however, the rate of increase in % bud burst was slower in the elevated temperature treatments than in the ambient temperature treatments. Time of bud burst was more synchronous and bud burst was completed within a shorter period in trees at ambient temperature (with and without elevated CO(2)) than in trees at elevated temperature. Exposure to elevated temperature reduced final % bud burst of both leader and branch terminal buds and reduced growth of the leader shoot. We conclude that climatic warming will influence the physiological processes of dormancy and cold hardiness development in Douglas-fir growing in the relatively mild temperate region of western Oregon, reducing bud burst and shoot growth.     

Chemical and physiological responses of four Turkish red pine (Pinus brutia Ten.) provenances to cold temperature treatments

Determining the adaptability to abiotic conditions and potential establishment success of tree species needs to be conducted before attempting to use a species in large-scale afforestation programs. In this study, the chemical and physiological performance of four Turkish red pine (Pinus brutia Ten.) provenances was investigated after exposure to artificial cold temperature treatments to determine their adaptability to cold environment for potential use in afforestation programs. Seeds were sown and raised for 24, 28, and 32 weeks and exposed to decreasing temperatures in an artificial freezer. Relative electrolyte leakage, chlorophyll fluorescence, and carbohydrate concentrations were measured to determine the variability between provenances. Results showed that diameter and height growth did not vary with origin for each of the three growth stages measured. Root electrolyte leakage values differed between provenances, confirming that cold stress was effectively causing physiological damages when plants were exposed to temperature at ?15 °C and below. The variability observed in the relationship between provenances and cold hardiness responses can be attributed to tree-to-tree variability within provenances and microsites conditions. There was generally no significant difference in chlorophyll fluorescence between provenances, also attributed to low genetic variation between provenances. Carbohydrate concentrations were also very variable and varied significantly among growth stages and provenances. High-altitude provenances had higher soluble carbohydrates concentrations in several cases, suggesting a relationship between altitude, soluble sugars, and cold hardiness. However, these trends were not consistent; therefore, we suggest that such hypotheses be confirmed through more comprehensive further studies.     

植物抗寒性的生理生态学机制研究进展

综述植物在冷驯化过程中发生的一系列生理生化变化.环境对植物抗寒性的影响主要与光诱导、温湿度以及气候的变化有关.植物表面形成冰层会引起植物的无氧呼吸,导致植物受害;光抑制诱导活性氧的产生,从而导致植物光合系统的退化,抗寒能力下降,而短日照诱导植物休眠,有利于植物抗寒.光敏色素则被认为是启动冷驯化的光受体;植物通过冷驯化增加碳水化合物的积累及病原体相关蛋白的合成,以增强对低温病原体的抵抗能力;气候的变化使植物遭受了更大的冷伤害风险.微管最初遇冷时部分的解体可以有效诱导植物抗寒性;抗氧化酶活性增强,植物体内糖、脯氨酸、多胺等内含物含量上升.植物休眠状态中的生理变化(种子的休眠、芽的休眠)与ABA敏感性的差异有关.对植物抗寒性分子机制的研究表明:COR基因的表达对于植物抗寒性和冷驯化是十分关键的;与气候梯度有关的基因梯度的分布说明寒冷地区的树种更为抗寒;多表型性状的数量性状分析,为重要的农艺性状标记辅助选择(MAS)提供基础.对植物抗寒过程中的信号转导进行研究发现,Ca2 是低温下参与调节冷驯化应答机制中信号转导途径的重要的第二信使.未来植物抗寒领域的研究热点为信号转导和基因调节,低温抗性的遗传学和遗传应用及代谢组学,气候变化对于植物抗寒的影响等方面.     

低温对园林植物体内渗透物质与丙二醛含量的影响

随着地球温室效应的增加，世界各地极端天气不断出现，极端低温是重要的一种表现形式，而极端低温会对园林植物造成极大的伤害。园林植物为抵御低温的伤害，其体内会发生一系列的生理生化变化，其中，渗透物质含量的变化可以反映园林植物抗寒性的强弱，而丙二醛含量直接反应树体受低温伤害的程度。作者列举了大量的试验研究结果，详细分析了低温影响下园林植物体内可溶性蛋白，可溶性糖，游离脯氨酸含量的变化规律，同时，分析了园林植物体内丙二醛含量的变化情况，为合理判断园林树木抗寒性强弱、园林植物引种以及养护提供理论支持。     

Relationships among cold hardiness, root growth potential and bud dormancy in three conifers

Greenhouse-cultured, container-grown ponderosa pine (Pinus ponderosa var. scopulorum Engelm.), interior Douglas-fir (Pseudotsuga menziesii var. glauca (Beissn.) Franco) and Engelmann spruce (Picea engelmannii (Parry) Engelm.) were cold acclimated and deacclimated in growth chambers over 19 weeks. Stem cold hardiness, total new root length at 14 days and days to bud break were measured weekly. Relationships among cold hardiness, root growth potential (RGP) and bud dormancy suggest that cold hardiness, which can be measured quickly, could provide a useful basis for estimating the two other parameters. During cold acclimation, there was a lag period in which stem cold hardiness remained at -15 degrees C and RGP was at a minimum, in all three species. Douglas-fir and Engelmann spruce buds remained fully dormant during this lag period. Ponderosa pine buds had no chilling requirement for the loss of dormancy, and reached quiescence during the lag period. Immediately following the lag period, as stem cold hardiness progressed to -22 degrees C, RGP increased to a high plateau in all three species, and Douglas-fir and Engelmann spruce buds approached quiescence. Cold deacclimation and bud development began immediately on exposure to warm, long days, but RGP remained high until stem cold hardiness returned to approximately -15 degrees C. At bud break, cold hardiness and RGP were at the minimum.     

Walnut (Juglans spp.) ecophysiology in response to environmental stresses and potential acclimation to climate change

? Context

Walnuts (Juglans spp.) are ecologically and commercially important trees, yet synthesis of past and current research findings on walnut ecophysiology is lacking, especially in terms of potential acclimation to climate change.

? Aims

This study aims to (1) investigate walnut ecophysiology by comparing its attributes to associated deciduous angiosperms, (2) address potential acclimation of walnut to climate change, and (3) identify areas for prioritization in future research.

? Results

There is considerable uncertainty regarding the magnitude of potential effects of climate change on walnut. Some studies tend to indicate walnut could be negatively impacted by climate change, while others do not. Walnut may be at a disadvantage due to its susceptibility to drought and frost injury in current growing regions given the projected increases in temperature and extreme climatic events. Other regions that are currently considered cold for walnut growth may see increased establishment and growth depending upon the rate of temperature increase and the frequency and severity of extreme climatic events.

? Conclusion

Research investigating a combination of environmental factors, such as temperature, carbon dioxide, ozone, water, and nitrogen is needed to (1) better project climate change effects on walnut and (2) develop management strategies for walnut acclimation and adaptation to climate change.     

三种槭树三年生幼苗抗寒性研究

温度影响着植物的自然地理分布,其中极端低温会给辽东的城市园林绿化建设以及绿化树幼苗培育带来诸多不利,致使许多观赏性绿化树种栽植和培育过程中,因遭受低温胁迫超过其低温耐受极限造成树木整株死亡。近年对于彩叶树抗寒性研究比较多,但对于苗圃播种苗、移床苗抗寒性的讨论和研究不是很多。以秋季红叶观赏性为主要特点的元宝枫、色木槭、拧筋槭3年生幼苗作为研究对象,通过低温处理,然后测定其相对电导率,并用logistic方程回归求其半致死温度,研究3种槭树幼苗的抗寒性,为辽东山区苗圃地培育绿化用彩叶树幼苗提供依据。     

The ecological and functional correlates of nocturnal transpiration

Contrary to the conventional theory of optimal stomatal control, there is substantial transpiration at night in many tree species, but the functional significance of this phenomenon remains uncertain. To investigate the possible roles of nocturnal transpiration, we compared and contrasted the correlations of both nocturnal and diurnal sap flow with a range of traits in 21 temperate deciduous tree species. These traits included soil water affinity, shade tolerance, cold hardiness, nitrogen concentration of tissues, minimum transpiration rate of excised leaves, growth rate, photosynthetic capacity, stomatal length and density, and the water potential and relative water content of leaves at the wilting point. Nocturnal sap flow was higher in species with higher leaf nitrogen concentrations, higher rates of extension growth and lower shade tolerances. Diurnal sap flow was higher in species with higher leaf nitrogen concentrations and photosynthetic capacities on a leaf area basis. Because leaf metabolism and dark respiration, in particular, are strongly related to leaf nitrogen concentration, our findings suggest that nocturnal transpiration functions to sustain carbohydrate export and other processes driven by dark respiration, and that this function is most important in fast- growing shade-intolerant tree species.     

苗木生理与质量研究进展

综述了矿质营养、碳水化合物含量、水分状况、生长调节物质含量、耐寒能力等苗木生理状况与质量的关系。对根生长势、电阻抗等10种苗木质量生理指标的测定方法作了简要介绍。     

我国邓恩桉抗寒性研究进展

邓恩桉具有生长快、材性好、耐寒的特点，成为我国桉树北移种植的优良树种。本文概述了国内有关邓恩桉抗寒性的研究动态，讨论了邓恩桉抗寒性与细胞膜系统、保护酶系统等方面的相关性，参考其他植物抗寒性研究方法与思路，对邓恩桉抗寒性的进一步研究提出了一些设想。     

几个新选育优良枣品种（系）的抗寒性评价

以4个新选育的枣品种（系）的发育枝为试材（以冬枣Ziziphus jujuba Mill．CV．Dongzao为对照）,采用电导法并配以Logistic方程和干物质含量法,估测了抗寒性。研究结果表明：不同品种抗寒性不同,涞水铃枣抗寒性高于毛卜彦铃枣;月光枣抗寒性高于辣椒枣和冬枣。随树龄的增加,当年生发育枝的抗寒性增加,随枝龄的增大,抗寒性增强。本研究就干物质含量法和电导法在评价枣树抗寒性中的应用进行了讨论。     

四川核桃栽培适宜性区划研究

采用主成分分析法,确定了影响四川核桃生长发育的主导气候因子为,年均温、≥10℃积温、年极端低温、年日照时数、年降水量、1月平均气温和7月平均气温.通过对气候因子和土壤因子的适宜性综合分析,结合四川核桃主产区气候条件和生物学特性,得出全省核桃主要适宜的生态指标为,海拔400～2 800 m、土壤pH值5.5～8.5、土层厚度≥60 cm、≥10℃积温3 000 ～6 500℃,年平均气温9～18℃、年极端低温≥- 15℃、年降水量400～1 200 mm、年日照时数≥1 300h、1月平均气温≥-1℃、7月平均气温≤28℃.由此将四川划分为四川盆地北缘、东北缘核桃中心栽培区,川西高山峡谷核桃中心栽培区,川西南山地泡核桃中心栽培区,四川盆地中部核桃、泡核桃一般栽培区4个栽培区,对各区域核桃适宜性进行了评价,为四川核桃产业发展提供了科学依据.     

Assessment of seedling storability of Quercus robur and Pinus sylvestris

Pedunculate oak (Quercus robur L.) and Scots pine (Pinus sylvestris L.) seedlings were lifted on several occasions during autumn 1997 to determine the relationships between storability and frost hardiness. On each lifting date their physiological status was determined by assessment of shoot and root electrolyte leakage and frost hardiness, assessed as freeze-induced electrolyte leakage. Additional seedlings were simultaneously cold-stored for field planting and assessment of preplanting root growth potential in April 1998. First year field performance was determined the following winter. Storability and cold acclimation patterns differed between the two species. Both were negatively affected by early lifting, but oak was less sensitive with respect to survival, and pine attained tolerance to cold storage more rapidly and earlier with respect to growth increment. The correlations between shoot frost hardiness and performance suggest that freeze-induced shoot electrolyte leakage (SEL_diff?20) below a threshold of 5% is a good storability predictor for Scots pine in Denmark. A completely reliable criterion for pedunculate oak could not be established.     

持续低温对彩叶树木枝条内渗透物质影响的研究

试验研究了4种彩叶树木在-20℃低温持续胁迫下离体枝条内渗透物质含量变化规律,为揭示离体枝条生理特性和判断树木抗寒性提供理论依据。试验以处于深休眠的紫叶矮樱,美国红栌,鸡爪槭,元宝枫为试材,离体枝条在保水条件下,使用冰箱提供-20℃低温胁迫,3次重复。结果表明:4种彩叶树木枝条内可溶性糖含量呈现出升高的变化,升高幅度分别达到93.56%,162.45%,114.95%,57.19%;美国红栌枝条内可溶性蛋白表现为先升高后降低的变化,其余3个树种表现出一直升高的变化,试验末期含量显著高于第3天;紫叶矮樱和鸡爪槭试验期间游离脯氨酸含量无显著差异,美国红栌和元宝枫第15天含量显著高于第3天。综合分析认为,彩叶树木离体枝条在-20℃低温胁迫下仍然具有一定的生理活性,紫叶矮樱抗寒性略高于其他3个树种。     

秭林一号核桃良种选育

为选择适合宜昌地区发展的核桃早实品种,本研究组自1992～2004年,从全国各地引进早实核桃良种进行筛选,经过对参试品种生长量测定、物候期观察、坚果品质测定及抗病性、抗寒性调查,确认云新一号为宜昌地区表现最好的早实品种,2012年湖北省林木品种审定委员会将该品种认定为良种并命名为“秭林一号”核桃.     

Autumn frost hardiness in Norway spruce plus tree progeny and trees of the local and transferred provenances in central Sweden

Reforestation with provenances from locations remote from the planting site (transferred provenances) or the progeny of trees of local provenances selected for superior form and vigor (plus trees) offer alternative means to increase yield over that obtained by the use of seed from unselected trees of the local provenance. Under Swedish conditions, Norway spruce (Picea abies (L.) Karst.) of certain transferred provenances generally has an advantage in productivity relative to the local provenance comparable to that of progeny of plus trees. The aim of this study was to explore the extent to which productivity gains achieved by provenance transfer or the use of plus tree progeny are associated with reductions in autumn frost hardiness, relative to that of trees of the local provenance. In a field trial with 19-year-old trees in central Sweden, bud hardiness was tested on four occasions during the autumn of 2002. Trees of the local provenance were compared with trees of a south Swedish provenance originating 3 degrees of latitude to the south, a Belarusian provenance and the progeny of plus trees of local origin. The Belarusian provenance was the least hardy and the local provenance the most hardy, with plus tree progeny and the south Swedish provenance being intermediate in hardiness. Both the Belarusian provenance and the plus tree progeny were significantly taller than trees of the other populations. Within provenances, tree height was negatively correlated with autumn frost hardiness. Among the plus tree progeny, however, no such correlation between tree height and autumn frost hardiness was found. It is concluded that although the gain in productivity achieved by provenance transfer from Belarus was comparable to that achieved by using the progeny of plus trees of the local provenance, the use of trees of the Belarus provenance involved an increased risk of autumn frost damage because of later hardening.     

Cold hardiness and transplant response of Juglans nigra seedlings subjected to alternative storage regimes

? Effects of overwinter storage regimes on seedling cold hardiness and physiological vigor are relatively unexplored, particularly for temperate deciduous forest tree species.

? We evaluated influence of storage duration (0, 66, 119, or 175 d) on electrolyte leakage of stem and root collar tissues following exposure to a series of freeze-test temperatures in black walnut (Juglans nigra L.) seedlings sampled from cold (3 °C) or freezer (?2 °C) storage. Seedlings were subsequently transplanted into a controlled growth chamber environment for two months.

? Regardless of storage temperature, mean LT₅₀ was lowest for seedlings stored for 66 d (≤ ?34 °C) and increased dramatically after 119 d (≥ ?13 °C).

? Root collar tissue had lower LT₅₀ than stem tissue after 119 d for cold-stored seedlings, reflecting importance of evaluative tissue type. Days to bud break shortened with increasing storage duration up to 119 d and stabilized thereafter for both storage regimes. Root growth potential was maximized after 119 d of storage, and subsequently declined for cold-stored seedlings. Height growth increased following storage, regardless of duration.

? To promote stress resistance and transplant growth response, we recommend that black walnut seedlings from this genetic source be outplanted after approximately 66–119 d of storage.

     

Comparison of three cold hardiness tests for conifer seedlings

Greenhouse-cultured, container-grown ponderosa pine (Pinus ponderosa var. scopulorum Engelm.), interior Douglas-fir (Pseudotsuga menziesii var. glauca (Beissn.) Franco), and Engelmann spruce (Picea engelmannii (Parry) Engelm.) were cold acclimated and deacclimated in growth chambers over 19 weeks. Cold hardiness was measured weekly by a whole-plant freeze test and by two quick tissue tests: freeze-induced electrolyte leakage of needles, and differential thermal analysis of buds. The whole-plant freeze test provided results in 7 days, and indicated differences in cold hardiness among stems, buds, and needles. Although the whole-plant freeze test could accurately measure cold hardiness, it was not precise, and it required destructive sampling. Results from freeze-induced electrolyte leakage and differential thermal analysis were available in 2 days and 1 hour, respectively. The freeze-induced electrolyte leakage test was a precise, sensitive and objective predictor of changes or differences in tissue cold hardiness. To determine actual cold hardiness, results could be calibrated to the response of the same tissue in the whole-plant freeze test. The speed and objectivity of differential thermal analysis made this test useful for rapid, general assessment of cold hardiness status, but calibration was difficult, and precision varied.     

常绿树种在越冬过程中光合速率的变化及其对低水势的反应

树木叶片的耐旱力因树种不同而异,也因树体的生长时期、在树冠上的部位和环境条件的不同,不断地变化。在自然生境和生长状况下,耐旱力的可靠指标怎样才能取得,目前尚未见到快速有效的测定方法。我们试图根据在模拟干旱(低水势的甘露醇溶液)条件下,叶片光合放氧受抑制程度的判定、耐旱潜力的比较及其变化规律,常绿树种在越冬过程中耐寒力与渗透调节能力的变化密切相关性,来弄清叶片耐寒力与耐旱力的变化是否也是同步的。