华北落叶松和白杆幼苗脯氨酸及淀粉含量对水分和光照变化的响应

以2年生华北落叶松和白杆幼苗为研究对象，通过人工控制条件下的幼苗栽培试验，测定不同光照、水分条件下脯氨酸含量、淀粉含量的变化，综合比较分析了华北落叶松和白析苗期生长对光照和水分变化的生理响应。研究结果表明：随着土壤水分的减少，华北落叶松和白不工幼苗脯氨酸含量增高，淀粉含量下降，且华北落叶松的变化都高于白杆，华北落叶松幼苗比白析幼苗对土壤水分胁迫的响应能力更强；随着光照的增强，也有相同的表现。光照和水分条件的变化对华北落叶松和白析幼苗脯氨酸和淀粉含量的影响具有叠加作用，2个树种对水分胁迫和强光照的响应机制一致，但树种间响应强度不同，华北落叶松的响应能力更强，华北落叶松具有比白术千更大的抗干旱胁迫的生理基础。     

干旱对2种沙棘生长和生理特性的影响

以采自四川省红原县的中国沙棘、西藏沙棘幼苗为试材,采用盆栽试验法,对不同土壤水分(对照,即100%田间持水量;中度干旱,即50%田间持水量;极度干旱,即30%田间持水量)条件下中国沙棘和西藏沙棘幼苗生长速率、根超微结构以及不同器官中的碳水化合物含量进行测定。结果表明:在不同水分处理下,中国沙棘生长速率明显高于西藏沙棘;但与对照相比,水分胁迫对中国沙棘的抑制效应更显著。与对照相比,水分胁迫均显著影响了2种沙棘幼苗不同器官中的碳水化合物的积累和分配。极度干旱胁迫下,中国沙棘有更多的根部淀粉、根可溶性总糖、根蔗糖和根果糖含量,表现出较强的根渗透调节能力;而水分胁迫对西藏沙棘地上茎和叶碳水化合物的影响比地下部分更显著。中度水分胁迫时,2种沙棘的根系超微结构未有明显变化;而极度水分胁迫时,2种沙棘均显示根细胞超微结构的损伤。表明中度水分胁迫下,中国沙棘和西藏沙棘表现出较好的适应能力,而极度水分胁迫不同程度地影响了2种沙棘幼苗的生长和碳代谢能力。     

干热河谷乡土树种清香木幼苗生长对不同水分梯度的响应

根据土壤的田间持水量设置不同的土壤水分含量梯度,通过对不同梯度下清香木幼苗的株高、叶片性状、生物量以及幼苗生长状态的观测和分析,旨在探讨清香木幼苗在水分缺失及过量的情况下对水分的利用情况及清香木幼苗在不同水分条件下生长的性状,了解幼苗对水分过多或过少胁迫的响应,以期在云南干热河谷地区的植被恢复、清香木的培育种植中能提供一定的理论指导和技术参考。研究结果表明,清香木幼苗期需水量较多,在田间持水量充足的条件下,幼苗生长较好,在相对田间持水量较小的条件下,幼苗虽然较正常水分条件下生长减慢,但仍能生长。研究结果表明,清香木幼苗对极端干旱的耐受性要高于对极端降水,同时随植株的生长,清香木对水分需求的敏感度降低。研究还表明,在不构成胁迫的环境中,幼苗的地上部分生物量的增加明显高于地下部分的生物量的增加,而在水分过多或过少胁迫下幼苗的地下部分生物量的增加会高于地上部分,而且在胁迫强度和胁迫时间的推移下,表现的更为明显,此种适应对策可以帮助幼苗吸收更多的水分和养分,以及减少蒸腾等损耗,从而适应逆境。     

光照、水分、基质对江南油杉种子萌发的影响

为了揭示江南油杉(Keteleeria fortunei var.cyclolepis)种子萌发对环境的适应性,设置光照、水分、基质等环境条件对江南油杉种子萌发进行胁迫研究。结果表明:光照对江南油杉种子萌发无显著性影响,种子萌发率为81.67%~83.33%,对幼苗生长具有一定影响;在持续黑暗胁迫条件下江南油杉幼苗均为黄化苗;间歇性光照对江南油杉种子萌发和幼苗生长均无显著影响。江南油杉种子在10%水分条件下不能萌发;在25%~30%水分条件下萌发效果最好,萌发率为75.00%左右;当基质中水分小于25%时江南油杉种子不能萌发或萌发效果不好,幼苗生长较差;当基质中水分大于30%时种子萌发和幼苗生长受到抑制。江南油杉种子在滤纸基质条件下萌发效果最好,种子萌发率为83.33%;在细沙基质条件下幼苗生长最好,胚芽长22.42 mm,胚根长53.08 mm。     

水分胁迫对不同种源柄扁桃幼苗生长特性的影响

将收集到的4个种源柄扁桃种子进行低温沙藏,在播种育苗基础上,开展水分胁迫试验和生长特征观测,结果表明:水分胁迫对柄扁桃幼苗的高生长和生物量均存在一定的抑制作用,同个种源内根冠比随水分胁迫的加剧呈增加趋势,而种源间的差异不明显,GYBBT的生长量和生物量在不同水分处理下均要高于其他种源,且其根冠比也较大,表明其适应干旱能力较强。     

山桃叶片光合生理参数对土壤水分的响应特征

为探明山桃幼苗叶片光合生理特性对土壤干旱胁迫的响应规律,明确干旱胁迫下山桃幼苗的光合作用特性,以期为山桃幼苗的水分栽植管理提供理论依据。本研究以3 a生山桃幼苗为研究对象,模拟设置土壤相对含水量(RWC)为90.49%～30.28%共5个水分梯度,采用便携式光合仪Li-6400,测定分析不同土壤水分条件下山桃叶片的光合光响应曲线,筛选适宜的光合光响应模型,探讨山桃叶片净光合速率(P_n)、光合光响应参数、蒸腾速率(T_r)和水分利用效率(WUE)对土壤水分的响应规律。土壤水分可显著影响山桃幼苗叶片的光合作用和蒸腾作用,直角双曲线修正模型可较好模拟不同土壤水分条件下山桃叶片光合光响应曲线。山桃叶片表观量子效率、最大净光合速率、光饱和点、光补偿点和暗呼吸速率随土壤水分的降低均呈现先升高后降低的趋势,在RWC为59.68%～74.26%时光照生态幅较宽,利用弱光能力较强。随土壤水分的降低,山桃叶片P_n和T_r呈现先升高后降低的变化趋势,分别在RWC为74.26%和59.68%下达最高值,而WUE表现为先降低后升...     

不同干旱胁迫对榆树幼苗根叶形态的影响

以科尔沁沙地1年生榆树幼苗为材料,采用盆栽控水方法,设置适宜条件、轻度、中度和重度干旱胁迫等4个水分处理梯度,研究干旱胁迫对榆树幼苗含水量、水分利用效率以及叶片面积、比叶面积和比根长的影响。结果表明:随着干旱胁迫程度增加,幼苗叶片含水量逐渐降低,茎含水量先升高后降低,根系含水量在轻度和中度胁迫下大于适宜条件;叶片面积在适宜条件和轻度胁迫下显著增加,在中度胁迫下下降;比根长和水分利用效率随着干旱胁迫程度增加而增加;重度干旱胁迫下幼苗无法存活。在科尔沁沙地,栽植榆树幼苗保证存活生长的最低土壤含水量为7.15%。     

干旱胁迫对杨树幼苗生长的影响

干旱是主要的环境胁迫因子之一,严重影响植物的分布与生长发育。通过选用辽宁阜新章古台沙地1年生杨树幼苗为材料,采用盆栽控水方法研究了不同土壤水分处理对幼苗生长状况、生物量分配、叶面积、组织器官含水量及水分利用效率等指标的影响。结果表明:干旱胁迫抑制了杨树幼苗株高和基径的生长,降低了叶片和茎生物量的积累,然而却增加了根系生物量,杨树将更多的碳水化合物分配到地下部分,导致其单位质量的根系更长,有利于其吸收水资源;同时轻度胁迫下,杨树幼苗增加了茎和根系的含水量,提高了水分利用效率;在科尔沁沙地,栽植杨树幼苗保证生长存活的最低土壤含水量为10.72%。     

优良白杨新品种BL193对水分胁迫的反应

用盆栽法设置３个土壤相对含水量，研究ＢＬ１９３苗木生长和生理指标对土壤水分胁迫的反应。结果表明，在水分胁迫条件下，苗木生长受到严重抑制，蒸腾速率和气孔阻力日变幅减小，净光合速率降低；随着水分胁迫的加剧，渗透调节能力得到一定程度提高；为维持苗木正常生长，土壤含水量应不低于田间持水量的６０％。     

赤峰36号杨幼苗对水分协迫的生理响应

以赤峰36号杨1 a生幼苗为材料,采用渗透胁迫处理的方法,研究杨树幼苗生理指标对水分不同强度胁迫的响应,结果表明:在3种水分强度胁迫下,杨树幼苗各生理指响应不同,当PEG体积分数为10%时,苗木水势和POD活性较对照变化明显,但MDA含量和质膜相对透性变化不显著,说明该强度的水分协迫未对杨树幼苗造成生理伤害;当PEG质量分数为15%时,虽然MDA含量较对照变化不显著,但苗木水势、POD活性和质膜相对透性却发生了显著变化,尤以质膜相对透性变化明显,说明该强度的水分协迫已对细胞造成了伤害;当PEG质量分数达到20%时,4种生理指标较对照均出现显著变化,说明该强度的水分胁迫对幼苗造成了严重伤害。     

Phosphorus Enhanced Establishment,Growth, Nutrient Uptake,and Productivity of Dalbergia sissoo Seedlings Maintained at Varying Soil Water Stress Levels in an Indian Arid Zone

We assessed interactive effects of varying levels of applied phosphorus fertilizer and water stress on growth, productivity, and mineral accumulation in container-grown Dalbergia sissoo L. seedlings. Height, collar diameter, leaf size and area, root volume and total biomass were reduced, and dry matter allocation to root was increased with increasing levels of soil water stress. The reduction was >32% in growth, >50% in leaf, and >77% in biomass when seedlings were grown with <50% of soil field capacity. Phosphorus application at the level of 10 mg kg^?1 soil enhanced stems and leaf biomass and nutrient accumulation at all irrigation levels, and thus tolerance to drought. Phosphorus responses to growth and biomass production increased with irrigation levels. Thus, 20 mg P kg^?1 soil is beneficial at sufficient soil water availability and a lower dose (i.e., 10 mg P kg^?1) is recommended under high soil water stress conditions to benefit growth and productivity of D. sissoo.     

水分胁迫对早实核桃生长和结果的影响

水分胁迫对早实核桃生长和结果的影响谷瑞升，郗荣庭，刘万生（河北农业大学园艺系保定０７１００１）（辽宁经济林研究所大连１１６０３１）关键词早实核桃，水分胁迫，生长和结果核桃是重要的经济林树种，早实核桃品种具有很高的栽培价值。然而我国的核桃产区集中于干旱...     

水分胁迫对栓皮栎幼苗生理特性及生长的影响

通过盆栽实验，研究了在不同的水分条件下栓皮栎幼苗生理特性的变化和苗木生长量的变化。研究表明，在水分胁迫初期，随土壤含水量的降低，栓皮栎叶片的净光合速率、蒸腾速率下降，而水分利用效率提高。在水分胁迫末期，由于长期的干旱胁迫，水分条件最差的一组苗木已干枯死亡，土壤含水量从38．123％下降到20．323％时，净光合速率和蒸腾速率均下降，水分利用效率也下降。随着土壤含水量的降低，苗高、地径和生物量均有下降的趋势，其中生物量下降的幅度最大。     

Morphological and water-stress characteristics of three Douglas-fir stocktypes in relation to seedling performance under different soil moisture conditions

This one-time greenhouse study examined the phenology, morphology, frost hardiness and response to moisture stress of three Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) stocktypes from the same seed lot. The types were mini-plug^TM transplants (MPT), 1+1 bareroot transplants (1+1), and 2+0 bareroot seedlings (2+0). In late summer and fall before lifting, 2+0 seedling set bud before 1+1 seedlings, 1+1 seedlings before MPT seedlings. The 2+0 seedlings appeared slowest to acquire frost hardiness in fall and seemed to deharden most rapidly in spring. Although the 2+0 seedlings were taller than the MPT stocktype, MPT and 2+0 seedlings were relatively similar in other morphological respects, but 1+1 seedlings were much larger. All stocktypes were potted on January 20, 1989, placed in a greenhouse, and subjected to 39%, 18%, 16%, or 6% soil water content (% dry weight) until the end of the experiment in mid-July 1990. The largest decrease in pre-dawn xylem water potential occurred with 16% and 6% soil water content; pre-dawn xylem water potential averaged over the three stocktypes generally declined 219% from low to high soil moisture stress. The 1+1 seedlings used more water than the other two stocktypes, and at maximum soil moisture stress, plant moisture stress increased in the order: MPT <2+0<1+1. During the 6-month greenhouse experiment, the larger 1+1 stocktype showed the most absolute growth, but the smaller stocktypes grew more on a relative scale. Growth of the stocktypes appeared to be related to differences in morphology and water-use patterns as the seedlings competed for available water within each pot. The results show that MPT seedlings, a new stocktype, performed as well as the more traditionally used 2+0 and 1+1 seedlings and that stocktype selection is important in reforestation efforts.     

Gas exchange during a soil drying cycle in seedlings of four black walnut (Juglans nigra L.) families

Photosynthetic and stomatal responses to a soil drying cycle were examined in half-sib seedlings of four walnut (Juglans nigra L.) families. Well-watered seedlings of an Iowa seed source had significantly higher rates of net photosynthesis than seedlings from New York or Michigan sources. This superior photosynthetic potential was associated with both greater stomatal conductance and mesophyll capacity for CO(2) fixation. In a drying soil, net photosynthesis and leaf conductance to water vapor of all families declined substantially, even under mild water stress. These responses were more strongly related to soil water status, as estimated by predawn leaf water potential, than to leaf water potential at the time of gas exchange measurement. There were no differences among families in the pattern of gas exchange response to developing water stress; however, families differed in capacity for recovery of gas exchange from water stress following rehydration. Sensitivity of photosynthesis of black walnut seedlings to water stress may be associated with poor growth and survival of this species in xeric habitats.     

Effects of soil moisture and light intensity on ecophysiological characteristics of Amorpha fruticosa seedlings

We investigated the combined effects of soil moisture and light intensity on the growth, development and ecophysiological characteristics of one-year old Amorpha fruticosa seedlings. Soil moisture and light intensity influenced the ecophysiological characteristics of Amorpha fruticosa seedlings. Soil moisture resulted in the decreases of growth rate, individual size, net photosynthetic rate, transpiration rate, leaf water loss rate (WLR), and biomass accumulation of plant parts, and led to increased leaf water saturation deficit (WSD). Under water stress, more photosynthetic products were allocated to root growth. With decreasing light intensity, net photosynthetic rate, transpiration rate, chla/b, water saturation deficit, water use efficiency, water loss rate and biomass accumulation declined, while Chla, Chlb, Chla+b and carotenoids (Car) increased and more photosynthetic products were allocated to stem and leaf growth. Maximum growth vigor, net photosynthetic rate and total biomass accumulation in Amorpha fruticosa seedlings was recorded at 75 80% soil water-holding capacity and 100% light density in greenhouse environments.     

Growth and water relations of seedlings of two subspecies of Eucalyptus globulus

Seedlings of Eucalyptus globulus Labill subsp. globulus grown in soil in pots in the greenhouse grew faster than seedlings of E. globulus subsp. bicostata, and responded better to added nutrients and water. However, water stress caused a greater reduction in the growth of shoots and roots, and in the root/shoot ratios of fertilized seedlings of subsp. globulus than in those of bicostata. More leaf surface wax was produced by seedlings grown in the presence of fertilizer and an adequate supply of water than by seedlings subjected to nutrient or water stress. Despite larger amounts of leaf surface wax, seedlings of subsp. bicostata had higher epidermal conductances than seedlings of subspecies globulus. However, epidermal conductances were reduced more by water stress and by fertilization in seedlings of subsp. bicostata than in subsp. globulus. Tissue osmotic potentials at full and zero turgor were reduced by water stress only in seedlings of subsp. bicostata and were increased by fertilizer only in seedlings of subsp. globulus. The results indicate that although seedlings of subsp. globulus have inherently higher growth rates, seedlings of subsp. bicostata are better adapted to drought.     

干旱胁迫对美国白蜡幼苗生理指标的影响

以美国白蜡2 a生实生苗为材料,采用盆栽方式进行干旱胁迫试验,测定苗木相对含水量、水分饱和亏、叶绿素含量及细胞质膜透性等生理指标,结果表明:从控水开始至12 d时,其叶片叶绿素含量从4.797 2 mg·g-1下降到3.693 2 mg·g-1,降低了23%;而相对电导率从39.11%上升到58.31%,上升了49.09%,相对电导率变化较大,但叶绿素含量相对稳定,膜系统未受到较严重损伤;胁迫12 d时叶片干鲜比仅比对照增加了9.73%,干旱致死临界点土壤含水量在5%以下,具有较强抗旱性。维持幼苗正常生长的临界土壤含水量为10%。     

干旱胁迫对红椿盆栽土壤含水率与植株伤害程度的影响

以2年生红椿盆栽幼苗为对象,开展干旱胁迫及复水试验,对各观测日的土壤含水率、叶片伤害指数及植株萎蔫度进行分析,结果表明:(1)各时间段受试盆栽土壤含水率及叶片伤害指数差异均呈极显著差异;(2)复水一定程度上改善了胁迫伤害;(3)土壤含水率与植株受伤害程度呈极显著的负相关关系。(4)要保证2年生红椿幼苗的正常生长,必须将土壤含水率保持在25%以上。