人心果原生质体分离初探

以人心果幼嫩叶片组织为材料,研究了酶液组合、酶解时间、酶液中甘露醇含量、pH值、温度等因素对其原生质体分离的影响,结果表明:以3%纤维素酶R-10+0.4%果胶酶Y-23为混合酶液,0.6 mol.L-1甘露醇为渗透压稳定剂,pH 5.6的酶液组合,在28℃的黑暗条件下振荡,酶解时间2 h,分离出的原生质体产量最佳,可达到12.4×106个.g-1。     

转基因741杨原生质体游离与纯化研究

以转双抗虫基因741杨无菌苗叶片为材料,对叶片原生质体游离、纯化方法及影响因素等进行了分析研究.结果表明,上部叶片产量和活力均高于其他叶位,在实验的浓度范围之内,Macerozyme R-10(离析酶)、Cellulase Onozuka R-10(纤维素酶)、Driselase (Sigma)(崩溃酶)对原生质体的产量和活力无显著影响.适宜转双抗虫基因741杨叶片原生质体游离与纯化的条件为无菌苗上部叶片为材料,0.7 mol/L甘露醇的CPW盐溶液预质壁分离1～1.5 h CPW+0.5％ Macerozyme R-10+0.25％ CellulaseOnozuka R-10+0.025％ Driselase (Sigma)+ 0.5 mol/L甘露醇(pH 5.7),酶解温度27℃,酶解时间10 h,用“过滤-离心-漂浮法”纯化原生质体.     

油桐叶肉细胞原生质体分离及瞬时转化体系的建立

【目的】探索油桐叶肉细胞原生质体分离的最适条件,建立油桐原生质体的遗传转化体系,使在油桐体内研究自身基因的功能成为可能。【方法】以油桐成熟叶片和组培苗幼叶为材料,通过酶解法成功分离得到油桐叶肉细胞的原生质体并确定最适分离条件。在此基础上,以获得的原生质体为受体系统,建立PEG介导的油桐原生质体基因转化方法。【结果】原生质体分离结果表明,酶解时间对原生质体产量和活性的影响最大,其次是纤维素酶浓度,而离析酶浓度和甘露醇浓度对原生质体产量和活性的影响较小。以成熟叶片为材料分离原生质体的最适条件为纤维素酶浓度1.5%、离析酶浓度1%、甘露醇浓度0.6 mol·L-1、酶解时间12 h,以组培苗幼叶为材料分离原生质体的最适条件为纤维素酶浓度2%、离析酶浓度1%、甘露醇浓度0.7 mol·L-1、酶解时间6 h。为了建立油桐原生质体的瞬时转化体系,通过PEG介导法将拟南芥MGT6基因导入到油桐原生质体中,结果发现MGT6蛋白定位于原生质体质膜,与之前报道的研究结果一致,这表明本研究建立的油桐原生质体转化方法可成功将外源基因导入油桐原生质体并使其表达。【结论】建立油桐成熟叶片和组培苗幼叶叶肉细胞原生质体的高效分离方法,综合考虑取材的便利性和对后续原生质体培养的影响,建议以组培苗幼叶为材料分离原生质体,分离条件为纤维素酶浓度2%、离析酶浓度1%、甘露醇浓度0.7 mol·L-1、酶解时间6 h。在分离得到油桐叶肉细胞原生质体的基础上,本研究建立的PEG介导的原生质体遗传转化方法能以油桐叶肉细胞原生质体为受体,高效地将外源基因导入其中并使外源基因表达。本研究结果不仅可促进油桐基础研究的发展,在通过细胞融合和基因工程手段进行油桐种质创新方面也具有重要意义。     

不同酶解条件对金边瑞香幼叶原生质体分离的影响

以室内培养的金边瑞香浅黄绿色、质地幼嫩的叶片为材料,探讨了影响其原生质分离的因素。结果表明:对原生质分离效果影响最大的是纤维素酶浓度和酶解时间;采用纤维素酶质量分数为0.2%、甘露醇质量浓度为0.6 mol.L-1、酶解时间为10 h时原生质分离效果最好,原生质体的产量为2.2×105个.g-1。     

根际加温对冬季月季切花生产的影响

以月季不同品种的一年生嫁接苗为试材,探讨了根际加温对冬季月季切花生产的影响.结果表明:根际加温显著提高了日光温室切花月季侧芽的萌发率,增加了更新枝的数量,使冬季的切花产量和品质明显提高;不同月季品种的切花产量和品质对根际温度的反应各不相同,Samantha和GoldenEmblem在根际温度为25℃时产量最高,切花产量分别比对照增加104.3%和94.4%,Blami和Tineke在根际温度为21℃时产量最高,分别比对照的切花产量增加46.2%和56.5%,Samantha、Blami和Tineke的切花长度分别在根际温度为18℃、21℃、25℃时最长,而根际温度对GoldenEmblem的切花长度没有显著影响;根际加温对月季叶片光合作用的影响不太大,不能解释根际加温可提高月季切花产量这一现象.     

杉木叶片原生质体分离及RNA提取体系的建立

【目的】以杉木组培苗幼嫩叶片为材料,分析不同因素对杉木原生质体分离的影响,建立杉木叶片原生质体分离体系,以期为杉木基因功能验证提供有效的技术平台;比较不同RNA提取方法,筛选获得杉木原生质体总RNA提取的有效方法,为今后利用杉木原生质体开展分子生物学研究提供技术支持,也可为其他林木原生质体的总RNA提取研究提供参考。【方法】选取杉木组培苗最上端未分轮的幼嫩叶片为材料,通过分析5种不同酶组合、真空处理时间(0、5、10、15、20 min)、渗透压(0.3、0.4、0.5、0.6 mol·L-1甘露醇)、BSA浓度(0.1%、0.2%、0.3%、0.4%)及酶解时间(1、2、3、4、5 h)5个条件,进行杉木叶片原生质体的分离。采用改良Trizol法、改良Trizol+10μg糖原法、CTAB-Li Cl法、CTAB-Li Cl+10μg糖原法、改良CTAB-异丙醇法、改良CTAB-异丙醇+10μg糖原法、天根RNA提取试剂盒法共7种方法提取杉木原生质体RNA,通过杉木内参基因和2个特异基因进行RNA质量验证,比较不同方法的提取效果。【结果】在1.5%纤维素酶R-10、1%离析酶R-10、0.2%果胶酶Y-23、0.5 mol·L-1甘露醇以及0.3%BSA的混合酶液中,真空处理10 min,酶解2 h,可分离出高活力的纯净杉木原生质体,其产量可达到7.27×106个·g-1,活力可达到94%。7种方法皆能提取出杉木叶片原生质体的总RNA,但不同方法间存在明显差异,其中改良Trizol法、改良Trizol+10μg糖原法、改良CTAB-Li Cl法、改良CTAB-Li Cl+10μg糖原法提取的RNA有不同程度的降解现象,其余方法所提取的RNA完整性较好,且OD260/280和OD260/230值均在1.8~2.0范围内;在RNA得率方面,改良CTAB-异丙醇+10μg糖原法可高效提取杉木原生质体RNA,106个细胞RNA产量平均可达到6.89μg,分别是改良CTAB-异丙醇法和天根RNA提取试剂盒法的1.73倍和1.58倍;综合考虑,改良CTAB-异丙醇+10μg糖原法提取杉木原生质体RNA的效果最好。【结论】以杉木组培苗幼嫩叶片为材料,分离条件为纤维素酶R-10浓度1.5%、离析酶R-10浓度1%、果胶酶Y-23浓度0.2%、甘露醇浓度0.5 mol·L-1、BSA浓度0.3%,真空处理10 min,酶解2 h,可大量获得高质量的杉木原生质体;利用改良CTAB-异丙醇+10μg糖原法,可高效提取杉木原生质体RNA,106个细胞RNA产量平均可达到6.89μg。研究结果为杉木重要性状关键基因的功能研究及其在育种中的应用提供了重要基础。     

不同光质处理对枫香幼苗叶色的影响

[目的]从生理生化角度揭示不同光质处理对枫香家系叶色变化的影响,为探索枫香叶色对光质的响应机理提供参考。[方法]以2个枫香家系的1年生幼苗为试验材料,测定其在不同光质处理下叶片叶绿素、类胡萝卜素、花青素、可溶性糖、类黄酮和苯丙氨酸解氨酶的含量并分析其相关性。[结果]结果表明:试验后2个枫香家系叶色较处理前有一定程度的变化。红光处理组枫香幼苗叶片叶绿素含量显著高于其它处理组,而蓝光处理组叶片叶绿素含量则显著低于其它处理组。蓝光处理后,2个枫香家系叶片花青素含量较对照有显著提高,而红光处理则减少了叶片花青素含量。同时蓝光处理能显著提高枫香幼苗叶片类胡萝卜素、可溶性糖和类黄酮含量以及苯丙氨酸解氨酶活力,红光处理效果较对照无显著差异。方差分析表明,不同光质处理对枫香幼苗叶片叶绿素含量影响显著,而对花青素量和类胡萝卜素含量影响不显著。[结论]2个枫香家系叶色在光质处理下有相同的变化趋势,红光处理可以促进枫香幼苗叶片叶绿素合成;蓝光处理可以促进枫香幼苗叶片积累更多的花青素。     

不同生物有机肥对红枣生长性状及品质影响研究

为探究施肥对红枣产量、品质、生长期性状的影响并筛选比较理想的施肥方案,开展了4种商品生物有机肥、1种农家肥的施肥试验。结果表明:处理2(生物肥0.420kg+20kg羊粪株~(-1))对红枣生长期新梢粗、百叶质量、叶绿素含量的提高效果优于其他处理,分别比对照提高了24.63%、28.70%、4.10%;每种方案均能显著增加红枣单株产量和单果质量,其中单果质量以处理1(生物肥20kg株~(-1))、处理2效果较显著,分别比对照增加了26.46%和14.08%;单株产量以处理4[微生物菌肥0.075kg(1∶300配比)+20kg羊粪株~(-1)]、处理1和处理2影响最显著,分别比对照增加了157.95%、128.16%和124.08%;对红枣品质的影响以处理3(生物肥20kg株~(-1))效果最好,其中维生素C达666.55mg(100g)~(-1)。因此,施用生物有机肥对提高红枣生长期性状和产量以及改善红枣品质均有影响。     

模拟酸雨对台湾桤木叶片K~+,Ca~(2+),Mg~(2+)渗出量的影响

通过喷淋试验,研究不同pH模拟酸雨对台湾桤木叶片K+,Ca2+,Mg2+渗出量的影响。结果表明:经过一定时间的酸雨胁迫,台湾桤木苗木叶片K+,Ca2+,Mg2+渗出量随着pH值的减少而增加,呈现负相关效应。处理I-V的叶片K+渗出量分别比对照(CK)升高34%,25.5%,17.4%,16.7%,11.4%;处理I-V的叶片Ca2+渗出量分别比对照(CK)升高36%,25%,18%,5%,3%;处理I-V的叶片Mg2+渗出量分别比对照(CK)升高58.3%,41.6%,37.5%,29.2%,22.1%。并且随着酸雨胁迫时间的延续,叶片K+渗出量和Mg2+渗出量的变化趋势均大致为先升高后下降,而Ca2+渗出量则不断降低。     

黄土高原丘陵沟壑区梨园垄沟覆地布效应的研究

以18年生‘酥梨’为试材,探究垄沟地布覆盖对黄土高原丘陵沟壑区旱地梨园不同土层土壤含水量、土壤水分相对盈余指数、枝条导水率、光合特性参数、树体营养生长以及果实产量和品质的影响。结果表明,垄沟地布覆盖可有效提高土壤含水量,各土层土壤水分相对盈余指数均为正数,同时,显著增加了梨树枝条叶比导水率、叶片相对含水量和叶绿素含量;梨树叶片净光合速率(P_n)、气孔导度(G_s)、蒸腾速率(T_r)和水分利用效率(WUE)均显著上升。与对照相比,垄沟地布覆盖可显著促进梨树新梢生长、叶面积增大和叶干质量增加。经垄沟地布覆盖处理后果实VC含量、横径及单株产量均显著提高,分别较对照提高了35%、3.7%和21.6%,可溶性固形物则明显降低,而可滴定酸、固酸比和果实硬度无显著差异。因此,在旱作区可利用垄沟覆地布良好的蓄水保墒能力,改善树体营养生长,最终达到增加果实产量和提高果实品质的效果。     

人心果乳汁的流变学特性

通过测定浓度、pH值、温度、剪切力变化等对人心果乳汁溶液粘度的影响及与黄原胶的协效性,对人心果乳汁溶液的流变学特性进行了研究.结果表明:随着浓度的升高,人心果乳汁粘度逐渐上升;酸在一定程度上能降低溶液粘度;温度和剪切力均能改变溶液的粘度;人心果乳汁与黄原胶溶液有一定的协效性,但其协效性较低.     

Ecophysiological responses of a young blue gum (Eucalyptus globulus) plantation to weed control

Early weed control may improve the growth of forest plantations by influencing soil water and nutrient availability. To understand eucalypt growth responses to weed control, we examined the temporal responses of leaf gas-exchange, leaf nitrogen concentration (N) and water status of 7-month-old Eucalyptus globulus L. trees in a paired-plot field trial. In addition, we monitored the growth, leaf N and water status of the competing vegetation in the weed treatment. By the end of the 11-month experiment, complete weed control (WF treatment) of largely woody competitors increased the basal diameter of E. globulus by 14%. As indicated by pre-dawn water potentials of >?-?0.05 MPa, interspecies competition for water resources was minimal at this site. In contrast, competition for N appeared to be the major factor limiting growth. Estimations of total plot leaf N (g m(-2) ground) showed that competing vegetation accounted for up to 70% of the total leaf N at the start of the trial. This value fell to 15% by the end of the trial. Despite increased leaf N(area) in WF trees 5 months after imposition of weed control, the photosynthetic capacity (A(1500)) of E. globulus was unaffected by treatment suggesting that the growth gains from weed control were largely unrelated to changes in leaf-level photosynthesis. Increased nutrient availability brought about by weed control enabled trees to increase investment into leaf-area production. Estimates of whole-tree carbon budget based on direct measurements of dark respiration and A(1500) allowed us to clearly demonstrate the importance of leaf area driving greater productivity following early weed control in a nutrient-limited site.     

外源一氧化氮对鹅毛竹离体叶片衰老的影响

以花后鹅毛竹为试验材料,10～50 mg·L-1硝普钠(SNP)为NO供体,研究外源NO对鹅毛竹离体叶片衰老的影响.结果显示:SNP预处理可不同程度地缓解鹅毛竹离体叶片衰老过程中蛋白质和叶绿素含量的下降,以30mg·L-1SNP处理效果最佳;与对照相比,离体处理5天后,叶片超氧化物歧化酶(SOD)、过氧化物酶(POD)活性分别下降26.2%,35.6%,PSⅡ最大荧光(Fm)、最大光化学效率(Fv/Fm)、潜在活性(Fv,Fo)分别降低42.1%,38.2%,77.0%,而暗适应下最小荧光(Fo)则升高89.5%;经30 mg·L-1 SNP预处理后,上述生理指标的变化均受到显著抑制.适当浓度的NO预处理能够有效延缓花后鹅毛竹离体叶片的衰老进程.     

广西人心果开花习性研究

对广西人心果开花习性、花粉萌发和传粉方式进行研究,结果表明;人心果1年可开多次花,不同的年份开花期有所变动,花期长。由结果母枝的顶芽形成混合花芽抽生结果枝,两性花,腋生,雌雄同熬,雌蕊和雄蕊在花瓣未展开前已成熟。花在白天开放,结果枝下部的花先开放,再由下到上逐渐开放。花粉在人工培养条件下,其萌发率低,柱头未分泌粘液前和花开放后期花粉萌发率为0．0％,成熟期的花粉萌发率可达5．2％,花刚开放时花粉萌发率最高达10．1％。人心果的传粉方式有2种,一是昆虫传粉,发现花蓟马是主要的传粉媒介;二是靠风的机械作用振落花粉而授粉。花量大,每结果枝平均着花为8朵,但平均落花率高达82．7％。     

Modeling the effect of physiological responses to green pruning on net biomass production of Eucalyptus nitens

Green pruning of Eucalyptus nitens (Deane and Maiden) Maiden increases instantaneous rates of light-saturated CO(2) assimilation (A), and changes patterns of total leaf area and foliage distribution. We investigated the importance of such changes on the rate of recovery of growth following pruning. A simple process-based model was developed to estimate daily net biomass production (G(d)) of three-year-old plantation-grown trees over a 20-month period. The trees had been pruned by removal of 0, 50 or 70% of the length of green crown, equivalent to removal of 0, 55 or 88% of leaf area, respectively, when the plantation verged on canopy closure. Total G(d) was reduced by only 20% immediately following the 50%-pruning treatment, as a result of both the high leaf dark respiration and low A in the portion of the crown removed compared to the top of the crown. Pruning at the time of canopy closure preempted a natural and rapid decline in G(d) of the lower crown. Although leaf area index (L) was approximately 6.0 at the time of pruning, high light interception (95%) occurred with an L of 4.0. The 50%-pruning treatment reduced L to 3.5, but the physiological responses to pruning were sufficient to compensate fully for the reduction in intercepted radiation within 110 days of pruning. The 70%-pruning treatment reduced L to 1.9, and reduced G(d) by 77%, reflecting the removal of branches with high A in the mid and upper crown. Physiological responses to the 70%-pruning treatment were insufficient to increase G(d) to the value of unpruned trees during the study. Model sensitivity analysis showed that increases in A following pruning increased G(d) by 20 and 25% in the 50- and 70%-pruned trees, respectively, 20 months after pruning. Changes in leaf area/foliage distribution had a greater effect on G(d) of 50%-pruned trees (47% increase) than did changes in A. However, the reduction in photosynthetic potential associated with the 70%-pruning treatment resulted in only small changes in leaf area/foliage distribution, which consequently had little effect on G(d). The effects of physiological processes occurring within the crown and in response to green pruning on G(d) are discussed with respect to pruning of plantations.     

黑暗和光照条件下低温胁迫对红花玉兰幼苗生理特性的影响

以25℃正常生长的苗木为对照,研究了在黑暗和光照条件下低温(5℃)胁迫对红花玉兰幼苗生理特性的影响,结果表明:低温胁迫下,质膜相对透性升高,可溶性糖及脯氨酸含量增加,且光照处理高于黑暗处理;可溶性蛋白含量下降,且光照处理的含量小于黑暗处理;SOD活性升高,且光照处理高于黑暗处理;光照处理POD活性升高较小,黑暗处理POD活性低于对照。可溶性糖含量、脯氨酸含量、SOD活性的提高可能是植株抗寒性机制的重要因子。     

Effects of elevated CO(2) on chloroplast components, gas exchange and growth of oak and cherry

Specific chloroplast proteins, gas exchange and dry matter production in oak (Quercus robur L.) seedlings and clonal cherry (Prunus avium L. x pseudocerasus Lind.) plants were measured during 19 months of growth in climate-controlled greenhouses at ambient (350 vpm) or elevated (700 vpm) CO(2). In both species, the elevated CO(2) treatment increased the PPFD saturated-rate of photosynthesis and dry matter production. After two months at elevated CO(2), Prunus plants showed significant increases in leaf (55%) and stem (61%) dry mass but not in root dry mass. However, this initial stimulation was not sustained: treatment differences in net assimilation rate (A) and plant dry mass were less after 10 months of growth than after 2 months of growth, suggesting acclimation of A to elevated CO(2) in Prunus. In contrast, after 10 months of growth at elevated CO(2), leaf dry mass of Quercus increased (130%) along with shoot (356%) and root (219%) dry mass, and A was also twice that of plants grown and measured at ambient CO(2). The amounts of Rubisco and the thylakoid-bound protein cytochrome f were higher in Quercus plants grown for 19 months in elevated CO(2) than in control plants, whereas in Prunus there was less Rubisco in plants grown for 19 months in elevated CO(2) than in control plants. Exposure to elevated CO(2) for 10 months resulted in increased mean leaf area in both species and increased abaxial stomatal density in Quercus. There was no change in leaf epidermal cell size in either species in response to the elevated CO(2) treatment. The lack of acclimation of photosynthesis in oak grown at elevated CO(2) is discussed in relation to the production and allocation of dry matter. We propose that differences in carbohydrate utilization underlie the differing long-term CO(2) responses of the two species.     

Growth response of Douglas-fir seedlings to nitrogen fertilization: importance of Rubisco activation state and respiration rates

High foliar nitrogen concentration ([N]) is associated with high rates of photosynthesis and thus high tree productivity; however, at excessive [N], tree productivity is reduced. Reports of excessive [N] in the Douglas-fir forests of the Oregon Coast Range prompted this investigation of growth and needle physiological responses to increasing foliar N concentrations in 1-year-old Douglas-fir seedlings. After 1 year of N fertilization, total seedling biomass increased with each successive increase in N fertilizer concentration, except in the highest N fertilization treatment. Of the many physiological responses that were analyzed, only photosynthetic capacity (i.e., Vcmax), respiration rates and leaf specific conductance (KL) differed significantly between N treatments. Photosynthetic capacity showed a curvilinear relationship with foliar [N], reaching an apparent maximum rate when needle N concentrations exceeded about 12 mg g(-1). In vitro measurements of ribulose-1,5-bisphosphate carboxylase (Rubisco) activity suggested that photosynthetic capacity was best related to activated, not total, Rubisco content. Rubisco activation state declined as foliar [N] increased, and based on its significant correlation (r2= 0.63) with foliar Mn:Mg ratios, it may be related to Mn inactivation of Rubisco. Respiration rates increased linearly as foliar N concentration increased (r2= 0.84). The value of K(L) also increased as foliar [N] increased, reaching a maximum when foliar [N] exceeded about 10 mg g(-1). Changes in K(L) were unrelated to changes in leaf area or sapwood area because leaf area to sapwood area ratios remained constant. Cumulative effects of the observed physiological responses to N fertilization were analyzed by modeling annual net CO2 assimilation (Anet) based on treatment specific values of Vcmax, dark respiration (Rdark) and KL. Estimates of Anet were highly correlated with measured total seedling biomass (r2= 0.992), suggesting that long-term, cumulative effects of maximum Rubisco carboxylation, Rdark and KL responses to N fertilization may limit seedling production when foliar N exceeds about 13 mg g(-1) or is reduced to less than about 11 mg g(-1).     

磷钾肥对芳樟生长及产油量的影响

[目的]研究芳樟在田间条件下对磷钾元素的响应,提高芳樟产油量同时降低经济成本,为芳樟林科学管理提供参考依据。[方法]以3年生的大田矮林叶用芳樟林为试验对象,设置了不施磷钾肥(CK)、施磷、施钾和磷钾配施4个处理,分析了磷钾对大田矮林叶用芳樟生长特性、叶片生理以及产量和出油率的影响。[结果]与CK相比,施钾显著增加了叶绿素a和叶绿素(a+b)含量,促进了芳樟的梢粗和分支生长,但对梢长、株高、冠幅生长有所抑制,增加了叶片宽度,显著降低叶长与叶宽比值,增强了叶片的过氧化物酶活性并降低丙二醛含量,显著减少了可溶性糖含量。磷肥对叶绿素b的合成效果最好,较CK也显著增加了叶绿素a和叶绿素(a+b)含量,但效果不及钾肥好,能促进芳樟梢长生长并增加梢分支数,但抑制了枝粗和叶片生长,增加了株高和冠幅,对过氧化物酶活性增强效果最显著,减少了丙二醛含量,增加了可溶性糖含量。磷钾配施显著增加了叶绿素a含量,促进了芳樟的梢长、梢粗及梢分支的生长,增加了叶片宽度和株高,但不利于叶长生长,对降低丙二醛的效果最佳,显著增加了过氧化物酶活性,降低了可溶性糖含量。磷钾配施较CK的芳樟枝叶产量和产油量分别增加23.9%和24.5%;施磷肥的较CK单株增产8.4%,产油量增加了5.9%。[结论]磷、钾肥均能促进芳樟叶片叶绿素的合成,增强对外界抗干扰的能力,但是对芳樟生长和枝叶发育的作用效果完全不同。仅施钾肥不利于芳樟生长和出油率的增加,因此,不推荐大田管理单施钾肥。施磷和磷钾配施均能提高枝叶生物量和产油量,(P150+K100)g·株~(-1)效果最佳。     

Effect of complete competition control and annual fertilization on stem growth and canopy relations for a chronosequence of loblolly pine plantations in the lower coastal plain of Georgia

Stem growth, developmental patterns and canopy relations were measured in a chronosequence of intensively managed loblolly pine stands. The study was located on two distinct sites in the lower coastal plain of Georgia, USA and contained a factorial arrangement of complete control of interspecific competition (W) and annual nitrogen fertilization (F). The W treatment increased growth rate for several years, while the F treatments led to sustained growth increases. The combination of the W and F treatments resulted in more than 180 Mg ha⁻¹ stem biomass production at age 15 which is more than double the production of control treatment. Stem biomass production is continuing to increase through age 15 as indicated by the current annual increment in stem biomass continuing to exceed the mean annual increment in stem biomass. The F treatment decreased wood quality by decreasing whole tree latewood specific gravity from 0.565 to 0.535 and by lengthening the transition from juvenile to mature wood from 4 to 5 years. Increased rates of stem growth in response to cultural treatments were largely mediated by increased leaf area, with strong functional relationships between leaf area index and current annual increment. However, growth efficiency (stem production per unit of leaf area) decreased with stand age. These results indicate that nutrient amendments are necessary for sustaining high rates of stand development on relatively nutrient poor lower coastal plain soils.