Physiological, morphological and anatomical leaf traits variation across leaf development in 'Corylus avellana'

<p indent=0mm>As light interception and leaf water shedding may require different leaf traits, trade-offs may exist between the leaves’ abilities in light interception and leaf water shedding. Moreover, such trade-offs may vary with the vertical canopy position as leaf traits vary with tree height. We studied the variations in leaf traits at different canopy positions to study how canopy positions would affect the trade-off between the traits related to light interception and leaf water shedding in subtropical broad-leaved trees. We used the standardized major axis regression method to analyze the relationships among leaf morphological traits (leaf thickness and leaf length/width ratio), configuration traits (leaf angle and leaf drip tip length), and physiological traits (photosynthesis-light saturation point and photosynthesis-light compensation point) between sun and shade leaves. The results are as follows: (i) There was no significant difference in the leaf thickness and leaf length/width ratio at different canopy positions (<italic>P</italic>>0.05). The leaf angle (34.92°±1.15°), light saturation point ((954.89±27.86) µmol/(m²·s)), and light compensation point ((29.45±1.02) µmol/(m²·s)) at the upper canopy were significantly higher than those at the lower canopy (leaf angle: 16.66°±0.50°, light saturation point: (520.74±15.47) µmol/(m²·s), and light compensation point: (12.54±0.38) µmol/(m²·s); <italic>P<</italic>0.05). However, the leaf drip tip length was significantly shorter at the upper canopy position ((4.26±0.15) mm) than at the lower canopy position ((7.18±0.22) mm; <italic>P</italic><0.05). (ii) There were significant correlations among leaf angle, leaf drip tip length, light saturation point, and light compensation point at different canopy positions (<italic>P</italic><0.05), but the leaf drip tip length and leaf length/width ratio were only weakly correlated at the upper canopy leaves (<italic>P</italic><0.05). (iii) Common slope (<italic>P</italic>>0.05) and isometric scaling existed among the leaf angle, light saturation point, and light compensation point at different canopy positions, but there was no common constant (<italic>P</italic><0.05). These results indicated that the canopy position does not alter the trade-off strategy between light interception and leaf water shedding. The leaf drip tip length and inclination were mainly affected by the light saturation point and light compensation point.

Understanding the genetic architecture of leaf morphological and physiological traits will help plant breeders develop high biomass poplar genotypes. Quantitative trait locus (QTL) studies combining next-generation sequencing techniques can advance our understanding of the genetic basis of complex traits. In this study, we measured 13 leaf morphological and physiological traits and identified quantitative trait loci (QTLs) in a Populus deltoides ‘Danhong’ × P. simonii ‘Tongliao1’ F1 population (500 progenies) using a high-density genetic map constructed by whole genome re-sequencing. This linkage map consisted of 5796 single nucleotide polymorphism (SNP) markers assigned to 19 linkage groups (LGs), spanning 2683.80 centimorgans (cM) of genetic length, with an average marker density of 0.46 cM. We identified 109 QTLs on 18 LGs for leaf morphological traits and 55 QTLs on 14 LGs for leaf physiological traits. One-hundred eight putative candidate genes were identified within the candidate genomic region. Co-expression network and gene ontology enrichment analyses suggested that these candidate genes were involved in the photosynthetic process. The differential expression patterns of the CYCLIN (Potri.015G112200) and RED CHLOROPHYLL REDUCTASE (Potri.007G043600) genes between two parents indicated their potential roles in leaf morphological and physiological traits. These findings decipher the genetic architecture of leaf morphological and physiological traits in the P. deltoides ‘Danhong’ × P. simonii ‘Tongliao1’ pedigree and provide candidate genes for future poplar genetic improvement.

PDF HTML阅读 XML下载 导出引用 引用提醒 木荷种源间光合作用参数分析 DOI: 10.5846/stxb201103080281 作者: 作者单位: 江西省林业科学院 作者简介: 通讯作者: 中图分类号: 基金项目: 江西省科技厅农业攻关项目(200110101003);江西省财政林业重大专项资助(200651010301) An analysis of photosynthetic parameters among Schima superba provenances Author: Affiliation: Jiangxi Academy o f Forestry Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:基于直角双曲线修正模型估算3个不同纬度的木荷种源(开平、太平和永丰种源)光补偿点、饱和点、最大净光合速率等参数,以便为评价不同木荷种源对环境的适应能力和优良种源选择等提供科学依据。结果表明:在3个不同纬度种源中,开平种源具有最高的净光合速率、最大净光合速率和较高的表观量子效率,且其生长速率最快;太平种源光饱和点最高,但其净光合速率、表观量子效率和最大净光合速率最低,其生长速率也最低;永丰种源具有较高的净光合速率、最大净光合速率和表观量子效率,其生长速率略高于太平种源。3个不同纬度木荷种源中,南部开平种源对当地环境具有较强的适应能力和生长潜力,具有较高的推广应用价值。 Abstract:Schima superba, a subtropical evergreen broad-leaved tree species, plays an important role in biological fireproofing and timber production in China. Previous studies focused mainly on the cultivation technique, fire forest belt construction and physiological ecology characteristic of S. superba. Photosynthetic parameters can be used to reflect tree growth characters. Most studies about photosynthesis of the S. superba focused on daily variation, relationship between photosynthesis and environment factors, photosynthesis rate and parameters of light response curve. Exponential function, rectangular hyperbola model, parabolic function and non-rectangular hyperbola model have been widely used to estimate parameters of light response curve. However, the maximum photosynthesis rates estimated by these models with data of light response curve were much larger than the measured values, and the light saturation points based on these models were much smaller. Moreover, these models can not model the phenomena that the photosynthesis rate decreased with increase of light intensity when light intensity was beyond light saturation points. The errors in photosynthesis rates and parameters estimation by these models of light response curve should be paid attention to. Especially, the errors caused by these models of light response curve will be amplified when the parameters of light response curve are used to the big scale models.. Fortunately, Modified rectangular hyperbola model overcomes these faults, and can model plant photosynthesis data in different light environments. It is very important for forestation to select good S. superba provenances according to provenance variation rules because S. superba has a wide natural distribution, and rich species variations. For S. superba, however, most parameters of light response curve were only estimated by exponential function, rectangular hyperbola model, parabolic function and non-rectangular hyperbola model which had much faults, and there was no available information about assessing different S. superba provenances based on the photosynthetic parameters such as maximum net photosynthetic rate, light compensation point and light saturation point. Therefore, we carried out a experiments to measure daily photosynthesis variation and light response curve of different S. superb provenances. The three provenances of S. superb were Kaiping in Guangdong province, Taiping in Anhui province and Yongfeng in Jiangxi province, respectively. The variables were measured using Li-6400 (LI-COR, Inc, Lincoln, NE, USA) from 9:00 to 16:00 on 10 to 13 October, 2010. Each measurement had three to five three replications. Based on modified rectangular hyperbola model, we calculated maximum net photosynthetic rate, light compensation point and light saturation point of S. superb from three provenances with three different latitudes. The results showed that the three provenances of S. superb had significant differences in photosynthetic parameters and tree growth (P < 0.05). Dark respiration rate, apparent quantum yield and maximum photosynthesis rate decreased in the following order: Kaiping > Yongfeng > Taiping. In addition, Kaiping provenance had higher light saturation than other provenances. However, no significant difference in the light compensation point was detected among different provenances. Additionally, tree growth rate in Kaiping provenance was significantly higher than Taiping and Yongfeng provenances. These results suggested that Kaiping provenance had the highest adaptability and growth potential in local region. Therefore, it had the highest application value. 参考文献 相似文献 引证文献

PDF HTML阅读 XML下载 导出引用 引用提醒 千岛湖次生林优势种植物光合生理生态特性 DOI: 10.5846/stxb201306041323 作者: 作者单位: 台州学院生态研究所,台州学院生态研究所,台州学院生态研究所;上海师范大学生命与环境科学学院,台州学院生态研究所;上海师范大学生命与环境科学学院 作者简介: 通讯作者: 中图分类号: 基金项目: 浙江省自然科学基金项目(Y507660); 台州学院培育基金资助项目(2013PY21) Photo-ecological characteristics of the dominant plant species in the secondary forest surrounding Qiandao Lake, Zhejiang, China Author: Affiliation: Institute of Ecology,Taizhou University,Institute of Ecology,Taizhou University,Institute of Ecology,Taizhou University;China;College of Life and Environmental Sciences,Shanghai Normal University;China,Institute of Ecology,Taizhou University;China;College of Life and Environmental Sciences,Shanghai Normal University;China Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:对千岛湖次生林优势种马尾松(Pinus massoniana)、苦槠(Castanopsis sclerophylla)、石栎(Lithocarpus glaber)、青冈(Cyclobalanopsis glauca)在不同季节的光合作用日变化、光响应、CO2响应以及相对叶绿素含量进行了分析,以期了解群落演替的内在机制。结果表明:(1)马尾松的净光合速率(Rn)日变化在4个季节均呈"单峰"曲线;苦槠在8月呈"双峰"曲线,其他3个月份均呈"单峰"曲线;石栎和青冈在5月、8月和11月的Rn日变化均为"双峰"曲线,有明显的光合"午休"现象,2月为"单峰"曲线。(2)马尾松和苦槠的Rn日积累值为8月最高,石栎和青冈为11月最高,且均与其他3个月均差异显著。4种优势种在4个季节的Rn日积累值的平均值大小为马尾松 > 苦槠 > 青冈 > 石栎,差异显著。(3)4个季节中,光饱和点(LSP)、光补偿点(LCP)、最大净光合速率(Amax)、暗呼吸速率(Rd)、最大羧化速率(Vcmax)、最大电子传递速率(Jmax)均以马尾松最高,表观量子效率(AQY)为马尾松最低。青冈在4个季节中具有最低的LSP、Rd和最高的AQY。苦槠和石栎的光合特性介于马尾松和青冈之间。(4)相对叶绿素含量以青冈最高,马尾松最低。总之,马尾松属强阳性树种,苦槠为阳性树种,石栎具有一定的耐荫性,青冈的耐荫性较强。 Abstract:The main factors that influence community succession in an evergreen broadleaf forest are differences in the ecological adaptability and eco-physiological traits of the various dominant plant species. Studies of the eco-physiological traits of these dominant species allow researchers to better understand the physiological demands and ecological traits of dominant species in their forest habitat and these studies also help researchers to recognize and understand the intrinsic mechanisms involved in forest regeneration and the mechanisms driving ecological succession in an evergreen broadleaf forest at the individual species level. In this study, we used a portable photosynthesis system to determine various physiological parameters associated with plant growth. We investigated the seasonal dynamics of the diurnal variations of photosynthesis, the responses to both light and CO2, and the relative chlorophyll content of the dominant plant species in the secondary forest surrounding Qiandao Lake, Zhejiang, China. The species included Pinus massoniana, Castanopsis sclerophylla, Lithocarpus glaber and Cyclobalanopsis glauca. The results showed the following. (1) Diurnal variations of the net photosynthesis rate (Rn) of P. massoniana exhibited a monomodal curve in all four seasons, while the variations in Rn for C. sclerophylla were bimodal in August but had a single curve in the other three time seasons investigated. Diurnal variations of Rn of L. glaber and C. glauca exhibited a typical bimodal curve with obvious "midday depression" in May, August and November but had a monomodal curve in February. (2) The diurnal integral values of Rn of P. massoniana and C. sclerophylla were significantly higher in August than those in the other three seasons, while those of L. glaber and C. glauca were significantly higher in November than those in the other three time periods investigated. The average value of the diurnal integral value of Rn in the four dominant species differed significantly in all four seasons and was ranked in the order of: P. massoniana > C. sclerophylla > L. glaber > C. glauca; (3) Compared with the other three dominant species, for P. massoniana, the light saturation point (LSP), light compensation point, maximum net photosynthetic rate, dark respiration rate (Rd), maximum rate of carboxylation and maximum rate of electron transport were highest in all four seasons, while the apparent quantum yield (AQY) was the lowest. The LSP and Rd of C. glauca were the lowest, while the AQY of C. glauca was the highest in the four seasons. Photosynthetic characteristics of C. sclerophylla and L. glaber were moderate among the four species. (4) In all four seasons, the relative chlorophyll content of C. glauca was the highest among the four dominant species, while that of P. massoniana was the lowest. All these results indicate that P. massoniana and C. sclerophylla are shade intolerant species and moderately shade intolerant species, respectively, while L. glaber and C. glauca are strongly shade tolerant species, although C. glauca is more strongly shade tolerant when compared with L. glaber. Based on these findings, we concluded that P. massoniana and C. sclerophylla will withdraw from the community during the succession. L. glaber and C. glauca will become the dominant species in the secondary forest surrounding Qiandao Lake as these forests mature. 参考文献 相似文献 引证文献

Response of foliar functional traits to experimental N and P addition among overstory and understory species in a tropical secondary forest

Trait syndromes underlying stand-level differences in growth and acclimation in 10 silver birch (Betula pendula Roth) genotypes

Abstract: The hybrid Azadirachta indica × Melia azedarach is a new plant variety that was obtained through somatic hybridization. The plant could grow normally in regions with an average annual temperature of 15 °C, and it had a higher concentration of active insecticidal substance in its seeds. Therefore, the hybrid will likely become a valuable new tree species in subtropical and warm temperate regions. However, the photosynthetic physiological characteristics of A. indica × M. azedarach remain unknown. The photosynthetic gas exchange of the hybrid at three different ages (one year old (AM1), three years old (AM3), and five years old (AM5)) were measured. The specific leaf mass per area (LMA), leaf N, leaf P, and leaf N/P of each tree sample were measured, and the photosynthetic N and P use efficiencies (PNUE and PPUE, respectively) were also calculated. The maximum leaf net photosynthetic rate Pa (based on area), Pm (based on mass), light saturation point (LSP), light compensation point (LCP), stomatal conductance (gs), and transpiration rate (Tr) of A. indica × M. azedarach decreased with increasing tree age, whereas the instantaneous water use efficiency (WUE) increased with age. The photosynthetic capacity showed no significant differences between AM3 and AM5 but was significantly higher in AM3 and AM5 when compared with AM1.The Pa, Pm, apparent quantum yield (AQY), LSP, gs, and Tr of A. indica × M. azedarach were significantly lower than that of the parental M. azedarach, whereas the dark respiration rate (Rd) and WUE were significantly higher than that of M. azedarach. A reduction in the maximal photosynthetic rate of A. indica × M. azedarach that was observed with increased age was primarily related to the increased LMA and the decline in leaf nitrogen (N) and leaf phosphorus (P) concentrations. Additionally, the decline in stomatal conductance (gs) was also an important factor leading to age-dependent reductions in the photosynthetic rate. These findings suggest that the tree’s age has a significant impact on A. indica × M. azedarach gas exchange during juvenile stages, and the photosynthetic capacity of the hybrid was significantly lower than that of the parental M. azedarach.

Aims Our objective was to investigate the effects of different light intensities on leaf morphology, photosynthetic capacity, heat dissipation and antioxidant enzyme activities in seedlings of Alnus formosana and A. cremastogyne from a hilly region near Lingyan Mountain in northwestern Sichuan Province in China. We also discuss photosynthetic acclimation and photoprotection strategies in seedlings of the two species Methods Three light regimes of 100%, 56.2% and 12.5% of natural light were simulated to match forest openings, forest gaps and forest canopies, respectively. After more than three months, we measured the parameters of gas exchange, including maximum net photosynthetic rate (Pmax), light saturation point (LSP), light compensation point (LCP), net photosynthetic rate (P n ), stomatal conductance (G s ), transpiration rate (T r ), intercellular CO 2 concentration (C i ), fluorescent non-photochemical quenching (NPQ), maximum efficiency of PSII photochemistry (F v /F m ) and light use efficiency (LUE), using a LI-6400 in seedling leaves. We also determined pigment contents per unit leaf area, lamina mass per unit area (LMA) and activity of antioxidant enzymes (superoxide dismutase, catalase and ascorbate peroxidase). Important findings LMA, carotenoid content (Cars), ratio of carotenoid to total chlorophyll (Car/Chl) and activities of superoxide dismutase, catalase and ascorbate peroxidase in leaves increased with the increase of light intensities. P max , LSP, LCP and NPQ tended to increase, while the chlorophyll content (Chl) and LUE decreased. However, the C i decreased with the increase of P n , G s and stomatal limitation value (L s ). We speculated that non-stomatal limitation was the main factor that inhibited P n . Seedlings of the two alder species could acclimate to different light regimes in this study through changing of physiological and morphological traits. Under all lightregimes, diurnal photoinhibition of photosynthesis, as judged by F v /F m , was significantly more severe in A. cremastogyne than in A. formosana. The acclimation capacity to high light regime was stronger in A. formosana than in A. cremastogyne. With the increase of light intensities, P max and antioxidant enzyme activities increased significantly, but not NPQ in A. formosana. The opposite trends occurred in A. cremastogyne. At the same light intensity, thermal dissipation was much lower, but P max was much higher in A. formosana than in A. cremastogyne. These results indicated that A. formosana seedlings might adapt resistance to photoinhibition through improving the use of solar energy by higher P max and antioxidant enzyme system, while A. cremastogyne seedling avoided photoinhibition mainly through converting excess light energy to heat energy in the form of non-radiative dissipation through the antenna system.

Effective irrigation can maintain the vigorous photosynthetic metabolism of leaves and lay a physiological foundation for their material production. Dry matter accumulation and leaf response to light and carbon dioxide of maize under irrigation quotas of 50 mm (Q0), 90 mm (Q1), 170 mm (Q2) and 250 mm (Q3) were studied. The results showed that the dry matter accumulation were significantly increased in Q2 and Q3 treatment compared with CK at R3, R4 and R6 stages. With the increase of light intensity, the photosynthesis-light response curves of Q2 and Q3 treatments were increased the most. The apparent quantum efficiency, maximum net photosynthetic rate, light saturation point and dark respiration rate of Q2 and Q3 treatments were significantly higher than those of Q0 and Q1 treatments at V12, R1 and R3 stages. The light compensation point was apparently lower than that of Q0 and Q1 treatments. The maize photosynthesis-CO2 response curves of Q2 and Q3 treatments demonstrated the largest increase with the increase of CO2 concentration. The CO2 saturation point, maximum net photosynthetic rate and carboxylation efficiency of Q2 and Q3 treatments were significantly higher than those of Q0 and Q1 treatments. The CO2 compensation point was obviously lower than that of Q0 and Q1 treatments. The study provides an effective irrigation and management method for maize in semi-arid area of west Jilin Province, China. When the irrigation quota reached 170 mm, the dry matter accumulation of maize and the response of maize leaves to light and CO2 were both better. 170 mm could be used as the reference value of maize irrigation quota in western Jilin Province.

PDF HTML阅读 XML下载 导出引用 引用提醒 模拟增温条件下接种AMF对夏蜡梅幼苗生长与光合生理特性的影响 DOI: 10.5846/stxb201501220177 作者: 作者单位: 台州学院生态研究所,台州学院生态研究所,台州学院生态研究所 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金（31400423）；浙江省自然科学基金（LQ14C030001）；台州学院生态学浙江省重点学科开放课题（EKD2013-07） Effects of AMF inoculation on growth and photosynthetic physiological characteristics of Sinocalycanthus chinensis under conditions of simulated warming Author: Affiliation: Taizhou University,, Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:全球变暖已对植物尤其是珍稀濒危植物产生重要影响。AMF对植物应对气候变化具有重要意义，但是在濒危植物应对气候变暖过程中发挥的作用并不清楚。以濒危植物夏蜡梅（Sinocalycanthus chinensis）一年生幼苗为对象，研究人工模拟增温条件下接种AMF对其生长、形态建成、光合生理、抗氧化酶活性和膜脂过氧化程度、营养物质积累和叶绿素相对含量的影响。实验共4个处理：模拟增温条件下添加AMF（AMF+SW）、添加AMF（AMF）、模拟增温（SW）和对照（CK）。结果表明：（1）接种AMF对幼苗株高、叶宽长比、总根长、根平均直径、根尖总数、比根长和比根表面积有显著影响。（2）AMF+SW条件下幼苗光合日进程呈现出明显"双峰"曲线，AMF显著提高叶片日均净光合速率（Pn）；光合有效辐射大于50 μmol m-2 s-1时，AMF+SW和AMF处理的Pn、最大净光合速率Pnmax和呼吸速率Rd显著高于CK；胞间CO2浓度大于100 μmol CO2/mol时，AMF+SW与AMF处理的Pn、AMF+SW处理的初始羧化效率（α）及AMF处理的光合能力（Amax）显著高于CK，而AMF+SW和AMF处理的CO2补偿点均低于CK。（3）AMF处理的叶可溶性糖显著高于其它处理，AMF+SW和AMF处理的叶可溶性蛋白显著高于CK。因此，AMF能显著促进夏蜡梅幼苗的形态建成和光合作用；在模拟增温条件下，接种AMF对夏蜡梅光合生理具有显著影响。 Abstract:The global climate warming is affecting ecosystems, especially endangered plant species whose distribution is mostly restricted to few areas. Arbuscular mycorrhizal fungi (AMF) form symbiotic associations with many plant species, supplying mineral nutrients to their host plants. Sinocalycanthus chinensis is a national second-class protected plant species, distributed in only a few areas in Zhejiang and Anhui provinces in China. Preliminary investigation has revealed higher infection rate of natural populations of S. chinensis by AMF. The role of AMF in S. chinensis under global warming has remained unknown. To reveal the effects of AMF on S. chinensis under the conditions of global climate warming, the pot experiment was conducted with one-year-old S. chinensis seedlings inoculated with AMF (inoculation of rhizosphere soil at a rate of 5%, v/v; soil without AMF was used as control) and temperature increase was simulated by an electric radiant infrared heater (+ 2℃ measured around the leaves; normal temperature was used as control). Growth rate, morphogenesis, photosynthetic physiological characteristics, antioxidant activities, membrane lipid peroxide level, nutrient content of S. chinensis seedlings were compared under four treatments: AMF, simulated warming (SW), both AMF inoculation and simulated warming (AMF + SW), and control (CK). The results showed that: (1) AMF inoculation had a significant positive effect on plant height and average root diameter, and a negative effect on the width-to-length ratio of mature leaves, total root length, total number of root tips, special root length (root length/root biomass), and special root surface area (root surface area/root biomass). Double-factor variance analysis showed that the average root diameter and total number of root tips was significantly correlated with AMF and SW. This showed that symbiotic association between AMF and S. chinensis may modify the nutrient absorption strategy of S. chinensis through modification in root morphology. (2) The diurnal change in net photosynthetic rate (Pn) of leaves in S. chinensis seedlings under AMF + SW treatment had a typical bimodal curve that was determinately regulated by stomatal conductance. AMF affected significantly the daily mean Pn. After fitting the photosynthesis light response using modified models of rectangular hyperbola, we found that Pn in plants with AMF + SW and AMF treatments were distinctly higher than that of CK when light intensity was more than 50 μmol m-2 s-1. The double-factor variance analysis showed that AMF significantly affected the daily mean Pn, maximum net photosynthetic rate, light saturation point (LSP), and dark respiration rate, whereas SW had a significant effect on LSP. Fitting of the CO2 response by using modified models of rectangular hyperbola revealed that Pn in plants under AMF + SW and AMF treatments was significantly higher than that in the CK with increasing the concentration of CO2. Initial carboxylation efficiency under AMF + SW treatment and photosynthetic capacity under AMF treatment were significantly higher than that of the CK. The CO2 compensation point after the treatment by AMF + SW or AMF was significantly lower than that of the CK. (3) The content of soluble sugars in leaves after the treatment with AMF was significantly higher than that in other treatments. The content of soluble proteins in leaves of plants treated with AMF + SW or AMF was distinctly higher than that of the CK. The double-factor variance analysis showed that SW and AMF + SW interaction had significant effect on the content of soluble sugars in leaves, and both AMF and SW had significant effect on the content of soluble proteins in leaves. The results provided the theoretical foundation for conservation and artificial cultivation of S. chinensis under conditions of global climate change. 参考文献 相似文献 引证文献

To get better insight into the photosynthetic mechanism of plant adaptation to strong light in intercropped maize, a field trial was carried out in 2014-2015 to investigate the effects of maize/peanut intercropping row ratio and phosphate fertilizer on diurnal variation in light intensity of maize canopy, SPAD value, and the curves of photosynthetic response of net photosynthetic rate (Pn) to photon flux density (PFD) and to CO2 of functional leaves. The field trial comprised 2 rows maize intercropped with 2 rows peanut (2:2, R1), 2 rows maize intercropped with 4 rows peanut (2:4, R2) and 2 rows maize intercropped with 8 rows peanut (2:8, R3). Results showed that the light intensity of intercropped maize canopy was R3>R2>R1. From pre-tasselling to filling stage, the SPAD value, apparent quantum efficiency (AQY), light compensation point (LCP), light saturation point (LSP), maximum net photosynthetic rate, carboxylation efficiency (CE), maximum electron transfer rate (Jmax), triose phosphate utilization (TPU), stomatal conductance (gs), transpiration rate (Tr) and Pn in ear leaves of intercropped maize were R3>R2>R1, but the intercellular CO2 concentration (Ci) was R1>R2>R3. At dough stage, the AQY, LSPn, gs, CE, Jmax and TPU in ear lea-ves of intercropped maize in R3 intercropping system were lower than those in R2 intercropping system. The photosynthetic indices, such as AQY, LSPn, CE, Vc max, Jmax and TPU were increased by phosphate fertilizer application. These results suggested that the key mechanisms that enhanced strong light utilization ability of intercropped maize were attributed to gradual improvement in gs, AQY, CE, Vc max, Jmax and TPU of ear leaves with increasing light intensity, however, beyond a certain light intensity, intercropped maize leaves were prone to premature senescence. Nonetheless, phosphate fertilizer could improve light utilization and delay leaf senescence in intercropped maize.

Rectangle hyperbola model (RH), nonrectangle hyperbola model (NRH), exponential model (EM), modified rectangle hyperbola model (MRH), and modified exponential model (MEM) were applied respectively for modeling the photosynthesis-light response curves (PLC) based on four types of curves (photosynthesis-light response curve of inhibition, PLCi, photosynthesis-light response curve of saturation, PLCs, photosynthesis-light response curve of unsaturation, PLCu andphotosynthesis-light response curve in weak light, PLCw) in canopy of 15 years old planted Larix olgensis tree in the Maoershan Forest Farm, Heilongjiang Province. The major photosynthetic physiological indexes including maximum net photosynthetic rate (Pn max), dark respiration rate (Rd), light compensation point (LCP), light saturation point at saturated light intensity (LSP) and apparent quantum yield (AQY) were calculated. All the five candidate models were comprehensively compared by the model goodness-of-fit and the precision estimations of photosynthetic physiological indexes in the four types of curves. The results showed that MEM model was only suitable for fitting the PLCi. MRH model showed the best goodness-of-fit for PLCi and PLCs(Ra2was 0.9986 and 0.9978, respectively). Meanwhile, NRH model expressed the best fitting result in PLCu and PLCw (Ra2 was 0.9996 and 0.9963, respectively). MRH had the lowest mean absolute value of relative error (MAPE) when evaluating Pn max in different types of curves (0.1%<MAPE<0.7%), but its precision estimation for LCP was relatively worse (2.5%<MAPE<9.4%). NRH model exhibited more accurate estimation for LCP of PLCs and PLCu, as well as Rd of PLCu(MAPE was 1.8%, 0.1%, and 3.9%, respectively). RH model represented better prediction effect for LCP of PLCi and Rd of PLCs(MAPE was 1.0% and 2.7%, respectively). EM was more sui-table for estimating LCP of PLCw(MAPE was 0.2%). Comprehensive analysis showed that MRH model not only proved well model goodness-of-fit and accurate estimation of photosynthetic physiological indexes, but also showed the highest stability when fitting different types of curves. As a result, MRH model was finally selected as the optimal canopy photosynthesis-light response model of planted L. olgensis tree.

SummaryPhylogenetic conservatism of tolerance to freezing temperatures has been cited to explain the tendency of plant lineages to grow in similar climates. However, there is little information about whether or not freezing resistance is conserved across phylogenies, and whether conservatism of physiological traits could explain conservatism of realized climatic niches. Here, we compared the phylogenetical lability of realized climatic niche, foliar freezing resistance and four morphological leaf traits that are generally considered to be adaptations to frost resistance in the Chilean species ofMyrceugenia, which grows in a wide range of habitats.We estimated the predicted niche occupancy profiles with respect to minimum temperature (minT) of all species. We measured foliar freezing resistance (using chlorophyll fluorescence), leaf size, leaf mass per area (LMA), stomatal and trichome densities of 10 individuals per species. Finally, we estimated phylogenetic signal, and we performed independent contrast analyses among all variables.We found that both foliar freezing resistance and minT were subject to a significant phylogenetic signal, but the former had a stronger signal. We also detected a significant, but weak correlation between them (r = 0.49,Pone tail = 0.04). Morphological traits evolved independent of any phylogenetic effect.Synthesis. Our results show that freezing resistance evolved in association with temperature niche, but with some delay that could result from phylogenetic inertia. Our results also show that morphological leaf traits are more labile than realized climatic niche and frost tolerance and that the formers probably evolved in association with microhabitat preferences.

Aims Our objectives were to find the optimal models for different drought stresses by comparing four light response models of photosynthesis in leaves of Periploca sepium growing in sand formed from seashells, investigate the adaptability law of parameters of light response models to drought stresses, and define the adaptability of P. sepium to the shell sand moisture conditions. Methods We used three-year-old P. sepium grown in shell ridge island of China’s Yellow River Delta as experimental material, set up four moisture conditions simulating those in shell sand, measured light responses of photosynthesis in leaves of P. sepium under different drought stresses using CIRAS-2 portable photosynthesis system, and fitted and analyzed the light response curves by four models: rectangular hyperbola, non-rectangular hyper-bola, exponential and modified rectangular hyperbola. Important findings The sequence of fitting effect of the four light response models was in descending order: modified rectangular hyperbola model nonrectangular hyperbola model exponential model rectangular hy-perbola model. This result was related to the latter three models not having extreme values, not fitting the process of light response curve declining after light saturation point (LSP), and not directly and accurately solving maxi-mum net photosynthetic rate (Pnmax) and LSP. Among them, the non-rectangular hyperbola model best fit dark respiration rate (Rd), the rectangular hyperbola model best fit light compensation point (LCP) and modified rectangular hyperbola model best fit Pnmax and LSP. The adaptabilities of the four models to different drought stresses varied. The modified rectangular hyperbola model well fit the curves under all the drought stresses, the rectangular hyperbola model and exponential model suited mild drought stress and the non-rectangular hyperbola model suited severe drought stress. The light response parameters, including apparent quantum yield (AQY), Rd, LCP, Pnmax and LSP, responded to drought stresses differently. AQY, Rd and LCP first increased and then decreased with the aggravation of drought stress, while Pn, Pnmax and LSP decreased gradually. LSP decreased by 5.2%, 16.3% and 34.55% under light stress, moderate stress and severe stress, respectively, in comparison to the control (1556 μmol·m–2·s–1). Pnmax decreased by 17.8%, 39.0% and 59.0% compared to the control (22.58 μmol·m–2·s–1). Light use capability of P. sepium leaf was strongest and light ecological amplitude (1520 μmol·m–2·s–1) was wid-est under sufficient water condition; photo-saturation and photo-inhibition occurred significantly, light use capa-bility weakened, and photosynthetic capacity was inhibited seriously under severe stress.

<title>Abstract</title> Functional plant traits are essential indicators of biodiversity conservation and ecosystem management. Understanding the relationships among leaf traits allows for the estimation of difficult-to-measure traits from those that are easier to quantify and widely distributed. This approach enhances the ability to analyze trait variation, identify scaling relationships, and address constraints in estimating plant-atmosphere carbon exchange. However, research on the correlation between photosynthetic capacity and leaf traits remains limited. Therefore, this study aims to explore the differences and correlations between leaf traits and photosynthetic capacity parameters across different growth forms. In this study, the leaf traits in 21 dominant woody species from a subtropical evergreen broad-leaved forest in southwestern China were assessed. Key photosynthetic parameters, including the maximum net photosynthetic rate, apparent quantum yield, light compensation point, and light saturation point, were investigated. Additionally, leaf traits such as leaf tissue density, leaf dry matter content, specific leaf area (SLA), leaf area, chlorophyll content, carbon content per unit leaf area, nitrogen content per unit leaf area (Narea), and carbon-to-nitrogen ratio were analyzed. Overall, no significant variations in maximum photosynthetic rate or photosynthetic quantum efficiency were observed between tree and shrub species in this forest. Shrub species exhibited greater adaptability and compensatory capacity to light conditions during photosynthesis. Using multiple linear regression models, SLA was identified as the key structural trait and Narea as the primary chemical trait for predicting the photosynthetic capacity of woody plants in this region. Nevertheless, for different growth forms, selecting optimal parameters for classification modeling in abiotic predictive models of photosynthetic capacity is recommended to improve prediction accuracy for subtropical evergreen broad-leaved forest plants.