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Table of Content
    Volume 38 Issue 7
    01 July 2014

    View of an evergreen broad-leaf forest in Tiantong National Forest Park (29°52′ N, 121°39′ E), Zhejiang Province, China. Zhang et al. and Shi et al. tested the effects of individual density and microtopography on Corner’s rules across woody plants in this region (Pages 655–674 of this issue) (Photographed by YANG Qing-Song).

      
    Research Articles
    Testing of Corner’s rules across woody plants in Tiantong region, Zhejiang Province: effects of individual density
    ZHANG Jian-Hong, SHI Qing-Ru, XU Ming-Shan, ZHAO Yan-Tao, ZHONG Qiang, ZHANG Fu-Jie, and YAN En-Rong
    Chin J Plan Ecolo. 2014, 38 (7):  655-664.  doi:10.3724/SP.J.1258.2014.00061
    Abstract ( 732 )   PDF (352KB) ( 1291 )   Save
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    Aims Corner’s rules reflect the architectural strategies of plants with respect to deployment of twig size and leaf size, as well as of the number of twigs and leaves. The objective of this study was to examine how Corner’s rules would vary among plants with different individual densities.
    Methods The study site is located in the Tiantong National Forest Park (29.87° N, 121.65° E), Zhejiang Province. We measured twig cross-sectional area (twig size), total leaf area (leaf size per twig), and the number of twigs at a given twig size (branching intensity) in woody plants across 25 plots differing in stem density to examine the effects of individual competition on Corner’s rules. The standardized major axis (SMA) analysis was conducted to determine the quantitative relationships of twig size with leaf size and branching intensity.
    Important findings Significant, positive allometric relationships between cross-sectional area and total leaf area were found in individual plants across all communities. There was no significant difference among communities of different density intervals in the slope of the linear regression between cross-sectional area and total leaf area of individual plants, and the common slope of the regressions was significantly greater than 1 (p < 0.001). The intercept was significantly greater for plants in communities with higher density than in those with lower density (p < 0.001), indicating that plants in a high density community support greater total leaf area than in a low density community for a given twig size. In contrast, a significant, negative allometric scaling relationship was found between branching intensity and cross-sectional area in individual plants across different communities. Also, no significant difference was found among plants in communities of different density intervals in the slope of the regression between branching intensity and cross-sectional area, and the common slope of the regressions was significantly less than –1 (p < 0.001). The intercept for the regression relationship between twig area and branching intensity was the same among plants in communities of different density intervals (p > 0.05), suggesting that plants in a high density community do not deploy more twigs per twig size than in a low density community. In summary, this study demonstrated that plants responded to changes in individual density by maintaining an invariant regression slope for the twig size-leaf size relationship and the twig size-branching intensity relationship, and that the Corner’s rules were not affected by individual density of the communities in the Tiantong region. However, changes in the intercept of the regression between twig size and leaf size indicate that deployment strategies between twig and leaf sizes could be adjusted with increasing individual plant competition, thus structuring species coexistence through niche differentiation.

    Testing of corner’s rules across woody plants in Tiantong region, Zhejiang Province: effects of micro-topography
    SHI Qing-Ru, XU Ming-Shan, ZHAO Yan-Tao, ZHOU Liu-Li, ZHANG Qing-Qing, MA Wen-Ji, ZHAO Qi, and YAN En-Rong
    Chin J Plan Ecolo. 2014, 38 (7):  665-674.  doi:10.3724/SP.J.1258.2014.00062
    Abstract ( 640 )   PDF (344KB) ( 1077 )   Save
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    Aims The size and quantity relationships between twigs and leaves can be used to describe the hydraulic properties of plants in response to environmental stresses. The objective of this study was to examine how twig-leaf relationship would vary with changes in micro-habitat conditions.
    Methods The study site is located in the Tiantong National Forest Park (29.87° N, 121.65° E), Zhejiang Province. We measured twig cross-sectional area (twig size), sub-twig cross-sectional area (sub-twig size), individual leaf area, total leaf area (leaf size per twig), the number of twigs at a given twig size (twig intensity), and the number of leaves at a given twig size (leafing intensity) across individual woody plants on 10 plots in each of the convex and concave habitats within an evergreen broad-leaved forest. The standardized major axis (SMA) analysis was conducted to determine the scaling relationships between twig size and leaf size, between sub-twig size and twig intensity, and between leaf size and leafing intensity.
    Important findings Significant, positive allometric relationships between twig cross-sectional area and total leaf area were found in plants in both types of micro-habitats (p < 0.001). There was no significant difference between the two micro-habitats in the slope of the regression between twig cross-sectional area and total leaf area, and the common slope of the regressions was significantly greater than 1 (p < 0.001). The intercept was significantly greater in plants of the concave habitat than in plants of the convex habitat (p < 0.001), indicating that plants in a concave habitat support greater total leaf area at a given twig size than in a convex habitat. Significant, negative allometric scaling relationships were found between twig size and twig intensity in plants in both micro-habitats. There was also no significant difference between the two habitats in the slope of the regression between twig size and twig intensity, and the common slope of the regressions was significantly less than –1 (p < 0.001). The similar intercept in the regression relationship of twig area and twig intensity between the two habitats suggests that plants deploy similar amount of sub-twigs per twig size in both types of habitat. In addition, significant, negative allometric scaling relationships between leaf size and leafing intensity were found to be consistently conserved across micro-habitat types, with the common slope being smaller than –1. A higher value of y-intercept in the scaling relationships of leaf area vs. leafing intensity for plants in the concave habitat indicates that at a given leaf area, more leaves were supported by plants in a concave habitat than in a convex habitat. Overall, plants in a concave habitat tend to deploy more large leaves per twig size than those in a convex habitat. This study demonstrated that both the Corner’s rules and the leaf size-number trade-offs could be generalized to apply at the small local spatial scales. The magnitude and quantitative adjustment of twig-leaf deployment manifests a selection preference of hydraulic properties of plants in coping with changes in water availability between concave and convex habitats.

    Impact of land use change during 1989–2009 on eco-capacity in Dongjiang watershed
    PENG Zi, GU Cheng-Yan, LIU Zhi-Yong, LIN Wen, and ZHOU Ping
    Chin J Plan Ecolo. 2014, 38 (7):  675-686.  doi:10.3724/SP.J.1258.2014.00063
    Abstract ( 542 )   PDF (515KB) ( 802 )   Save
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    Aims For sustainable watershed development planning, this study explores how ecological carrying capacity varies with changes in land use type and population.
    Methods Based on interpretation and analysis of five Landsat TM remote sensing images for 1989, 1994, 1999, 2004, and 2009, respectively, we examined the spatio-temporal patterns of land use change in the upper, middle, and lower reaches of Dongjiang watershed, using the total rate of change and single and integrated degree of land use dynamics as indicators. We calculated the total and per capita eco-capacity for the watershed in different years based on the population data, equivalence factors, and yield factors, in addition to the data of land use and land cover change, and further analyzed the factors determining the direction of changes in the eco-capacity.
    Important findings The results showed that: (1) there were apparent changes in the area for various land use types between 1989 and 2009. Despite the urban development, the coverage of forest vegetation increased, indicating lack of trade-off between urbanization and vegetation coverage. However, there were different patterns of change in land use among the upper, middle, and lower reaches. The land use type mainly varied from garden fields to forests in the upper and middle reaches of the watershed, while in the lower reach a change from arable land to build-up area dominated. (2) With the population growth along the Dongjiang watershed over the past two decades, although the per capita eco-capacity indicated a downward trend, its rate of decline lagged behind the population growth rate, and the total eco-capacity still showed a trend of increase, implying an optimization of land use types during the 20-year period. With respect to the temporal patterns, in the decade (1994–2004) after the end of the “10-year greening of Guangdong Province”, per capita eco-capacity tended to be relatively stable under the pressure of population growth, while it declined quickly in the periods of 1989–1994 and 2004–2009. The former period was probably associated with the development of reform and opening up policy, and the latter seemed to have less possibility on spatial optimization of land use types. The total eco-capacity showed different trends among the three regions; the upper and middle reaches exhibited an unstable trend (i.e., from decreasing to increasing), while the lower reach indicated a pattern of increasing–decreasing–stable trend. In conclusion, the increasing population demand for urbanization did not lead to deterioration of the forest resources in the watershed. To some extent, we could thus achieve the coordinated development in both aspects. In spite of increasing demand on ecological resources with population growth, we could establish a better strategy in land use to improve ecological services, and to reduce the downward trend in the per capita eco-capacity.

    Life table and survival analysis of Loranthus tanakae population in Mount Ziwuling
    ZHANG Liang, WANG Xiao-An, LIU Peng, WANG Xian, DENG Mei-Jiao, and ZHU Yun-Yun
    Chin J Plan Ecolo. 2014, 38 (7):  687-693.  doi:10.3724/SP.J.1258.2014.00064
    Abstract ( 503 )   PDF (277KB) ( 1120 )   Save
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    Aims Loranthus tanakae is a parasitic plant found on Quercus liaotungensis, which is a dominant and constructive tree species in forests of Mount Ziwuling. Our objective was to determine the ecological characteristics of L. tanakae in this region.
    Methods In the paper, based on investigations on the age structure of a L. tanakae population, a static life table was constructed, curves of survival, mortality, disappearance rate, and survival function were established, and the dynamics of the L. tanakae population were analyzed.
    Important findings The survival curve of the L. tanakae population studied is characterized as the type Deevey II, with relatively stable mortality. The pattern of the disappearance rate curve is similar to that of the morality curve; they both have two peaks: one occurring at the 5th age and the other at the 10th age. A fluctuation occurred in the risk rate curve at the 6th age. The survival curve showed a declining trend while the cumulative morality rate curve displayed an uptrend, and the L. tanakae reached the senescence after the 8th age. According to the age composition of the survival curve, the L. tanakae population studied remained stable in the early and middle stages, but declined in the late stage.

    Characteristics of seedling survival in habitats of hill and gully slopes in hill-gully Loess Plateau region of northern Shaanxi
    SU Yuan, JIAO Ju-Ying, and WANG Zhi-Jie
    Chin J Plan Ecolo. 2014, 38 (7):  694-709.  doi:10.3724/SP.J.1258.2014.00065
    Abstract ( 587 )   PDF (1011KB) ( 888 )   Save
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    Aims Seedling is the fundament of vegetation restoration succession and plays a very important role in ecosystems. The objective of this paper was to explore the characteristics of seedling survival in habitats of hill and gully slopes in a hill-gully Loess Plateau region.
    Methods Fifteen permanent plots in Zhifanggou and Songjiagou watershed in Ansai County were established for sentinel dynamic monitoring, and one-way ANOVA and hierarchical cluster analysis were used to analyze seedling density and survival rate in different habitats.
    Important findings There were significant differences in the characteristics of seedling survival among different habitats, with smaller seedling density and higher survival rates observed on the sunny slopes and larger seedling density but lower survival rate found on the shady slopes. In competition for survival, Artemisia gmelinii, Potentilla tanacetifolia, and Heteropappus altaicus etc. took advantage of quality and were characterized by a higher seedling survival rate, while Artemisia scoparia, Ixeris chinensis, Siphonostegia chinensis etc. adopted a strategy of “quantity” and characterized by a higher seedling density. The same species in different habitats had different survival curves, and the same survival curves in different habitats applied to different species. The seedlings of Artemisia gmelinii, Potentilla tanacetifolia, Stipa bungeana, Heteropappus altaicus, and Lespedeza davurica etc. had a strong survival capability in the rainy season and were easy to overwinter successfully, whereas the seedling survival capability in Artemisia scoparia, Dracocephalum moldavica, and Artemisia hedinii etc. was strong prior to the rainy season but weak in winter. The characteristics of seedling survival in different micro-environments also differed. A change in micro-environment affected seedling growth, survival, and overwintering to some extent. Thus, a proper tending for seedlings according to the survival characteristics of species is conducive to the seedling establishment and vegetation succession in the hill-gully Loess Plateau region.

    Estimating canopy photosynthetic parameters in maize field based on multi-spectral remote sensing
    ZHANG Feng and ZHOU Guang-Sheng
    Chin J Plan Ecolo. 2014, 38 (7):  710-719.  doi:10.3724/SP.J.1258.2014.00066
    Abstract ( 466 )   PDF (701KB) ( 1219 )   Save
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    Aims Determination of canopy photosynthetic parameters is key to accurate simulation of ecosystem function by using remote sensing methods. Currently, remote estimation of vegetation canopy structure characteristics has been widely adopted. However, directly estimating photosynthetic variables (photosynthetic capacity and efficiency) at canopy scale based on field spectrometry combined with CO2 flux measurements is rare.
    Methods In this study, we remotely estimated solar radiation use efficiency (εN, net ecosystem CO2 exchange/absorbed photosynthetically active radiation (NEECO2/APAR); εG, gross primary productivity/absorbed photosynthetically active radiation (GPP/APAR); α, apparent quantum efficiency) and photosynthetic capacity (Pmax) based on in situ measurements of spectral reflectance and ecosystem CO2 fluxes, along with observational data on micrometeorological factors during the entire growing season for a maize canopy in Northeast China.
    Important findings Results showed that the seasonal variations in Pmax and α exhibited a single peak; whereas the values of εN and εG were higher at the start of vegetative stage and then rapidly decreased with the development of maize until displaying a single peak at the intermediate and late stages of the growing season, coinciding with the occurrence of peak values in Pmax. A comparison was made on the predictive performance based on normalized difference vegetation index (NDVI), ratio vegetation index (RVI), wide dynamic range vegetation index (WDRVI), 2-band enhanced vegetation index (EVI2), and chlorophyll index (CI) in estimating four canopy photosynthetic parameters with any combination of two separate wavelengths at the range of 400–1 300 nm, which showed that EVI2 was most closely and linearly related to photosynthetic capacity and efficiency. This study demonstrates that multi-spectral remote sensing information is sensitive to the variations in canopy photosynthetic parameters in maize field and can be used to quantitatively monitor seasonal dynamics of canopy photosynthesis, and to accurately assess crop productivity and ecosystem CO2 exchange capacity.

    Mechanisms of photoinhibition induced by high light in Hosta grown outdoors
    LI Zhi-Zhen, LIU Dong-Huan, ZHAO Shi-Wei, JIANG Chuang-Dao, and SHI Lei
    Chin J Plan Ecolo. 2014, 38 (7):  720-728.  doi:10.3724/SP.J.1258.2014.00067
    Abstract ( 675 )   PDF (470KB) ( 1302 )   Save
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    Aims It has long been recognized that photoinhibition of photosynthesis is induced by high light. However, our recent studies are not consistent with this traditional view. Therefore, the objective of this study is to explore the induction of photoinhibition and its mechanisms under full sunlight outdoors.
    Methods Changes of leaf morphology, gas exchange, and chlorophyll a fluorescence were measured to investigate the induction and mechanisms of photoinhibition under high light in Hosta, which is a typical shade-tolerant plant.
    Important findings Hosta plants grown under full sunlight (HT) and low light (LT) developed sun- and shade-type leaf morphological characteristics, respectively. Under a full sunlight, Hosta plants had lower photosynthetic rate and chlorophyll content than under the LT; whereas, there were only slight difference in the maximum quantum yield of photosystem II (Fv/Fm) between the two treatments, suggesting that Hosta plants could grow normally under full sunlight without severe photoinhibition. After transition from the low to a high light (LHT), the photosynthetic rate and maximum quantum yield of photosystem II decreased sharply, reflecting that the LHT treatment led to irreversibly inactivation of photosystem II. Additionally, the shape of chlorophyll a fluorescence transients also changed significantly; the relative fluorescence yield of the K and J steps were reduced by 24.3% and 34.2%, respectively, indicating that the acceptor side of photosystem II was damaged more severely than the donor side. Consequently, we postulate that photoinhibition in Hosta leaves is mainly induced by the sudden enhancement of light intensity outdoors. Hosta can acclimate to high irradiance through leaf development outdoors. Our finding is of great significance in understanding the acclimation of plants to high light and cultivation of shade-tolerant plants in field.

    Photosynthetic characteristics in different peanut cultivars under conditions of drought and re-watering at seedling stage
    LI Guang-Hui, WAN Yong-Shan, LIU Feng-Zhen, and ZHANG Kun
    Chin J Plan Ecolo. 2014, 38 (7):  729-739.  doi:10.3724/SP.J.1258.2014.00068
    Abstract ( 682 )   PDF (461KB) ( 1128 )   Save
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    Aims In China, peanut (Arachis hypogaea) is mainly cultivated in the semi-arid and rain-fed areas, and drought is the most prominent environmental stress to its growth. However, studies on the physiological responses of different peanut cultivars to drought and re-watering are lacking. Our objectives were to investigate the relationship between photosynthetic characteristics and drought tolerance, and to explore the ability to recover from drought damage in different peanut cultivars.
    Methods A pot experiment was conducted with artificial water stress treatment, and the photosynthetic characteristics were determined in twelve peanut cultivars under the conditions of drought stress and re-watering at the seedling stage. The drought tolerance was assessed by drought resistance coefficient of biomass in seedling. The recovery capacity was assessed by compensatory growth of plant.
    Important findings Five cultivars, including ‘Shanhua 11’, ‘Rugaoxiyangsheng’, ‘A596’, ‘Shanhua 9’, and ‘Nongda 818’, showed over-compensatory growth after re-watering, and their capacity of compensatory growth had significant positive correlation with drought tolerance (p < 0.01). The net photosynthetic rate (Pn), stomatal conductance (Gs), intercellular CO2 concentration (Ci), maximum photochemical efficiency (Fv/Fm), PSII actual quantum yield (ΦPSII), and photochemical quenching coefficient (qP) all decreased over the course of drought stress, and then increased following re-watering, with the amplitude of changes being smaller in the more drought tolerant cultivars. Seven days of drought did not result in significant differences in the photosynthetic characteristics among majority of the peanut cultivars tested (p > 0.05). After 14 days of drought, the values of photosynthetic variables differed significantly among the peanut cultivars with different drought tolerance (p < 0.05). The values of Pn, Gs, ΦPSII, Fv/Fm, and qP in the cultivars ‘Shanhua 11’, ‘Rugaoxiyangsheng’, ‘A596’, and ‘Shanhua 9’ fully recovered five days after re-watering, while those in the cultivars ‘79266’, ‘ICG6848’, ‘Baisha 1016’, and ‘Hua 17’ did not fully recover even after 10 days of re-watering; the values of those photosynthetic variables were significantly greater (p < 0.05) in the more drought tolerant cultivars following re-watering. Correlation analysis showed that the drought tolerance was significantly and positively correlated with Pn, ΦPSII, Fv/Fm, and qP after 14 days of drought stress and after five days of re-watering, respectively (p < 0.01). Therefore, under drought stress at 40% of relative water content (RWC) for 14 days and after five days of re-watering at the seedling stage, the Pn, ΦPSII, Fv/Fm, and qP could be used for identifying the level of damage and recovery capacity of peanut cultivars. The cultivar ‘Shanhua 11’ can be used as a reference for drought adaptability identification in peanut.

    Effects of low light stress on rubisco activity and the ultrastructure of chloroplast in functional leaves of peanut
    WU Zheng-Feng, SUN Xue-Wu, WANG Cai-Bin, ZHENG Ya-Ping, WAN Shu-Bo, LIU Jun-Hua, ZHENG Yong-Mei, WU Ju-Xiang, FENG Hao, and YU Tian-Yi
    Chin J Plan Ecolo. 2014, 38 (7):  740-748.  doi:10.3724/SP.J.1258.2014.00069
    Abstract ( 731 )   PDF (1055KB) ( 1207 )   Save
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    Aims In recent years, intercropping system has become one of the major practice of peanut (Arachis hypogaea) cultivation in northern China because of the high land and energy utilization efficiency, to some extent compensating for the production loss caused by decreasing area of cultivation land. Intercropped peanut plants often have a lower pod yield compared with monoculture due to constraint on light availability. This study was conducted to explore the shade-tolerance mechanism in two peanut cultivars, ‘Huayu 22’ and ‘Baisha 1016’, that grew in an intercropping system, by studying chloroplast ultrastructure and rubisco activity under different levels of shading.
    Methods A field experiment was conducted with three levels of light treatments, including full natural light (CK), 50% natural light indensity (NLI), and 15% NLI. The ‘Huayu 22’ was used as a shade-tolerant cultivar and the ‘Baisha 1016’ as a shade-susceptible cultivar based on previous studies. Experimental plants of both cultivars were shaded for 40 days from emergency in 2006. Rubisco activity, the number and shapes of chloroplasts and starch grains, and number of grana and granum lamella were investigated in functional leaves of plants in all treatments.
    Important findings The functional leaves of peanut plants in the 50% and 15% NLI treatments had a lower rubisco activity than those in the CK treatment. In the ‘Baisha 1016’, the reduction in rubisco activity was 40.1% in the 50% NLI treatment and 59.4% in the 15% NLI treatment, respectively, compared to the CK treatment; whereas no significant differences were found among treatments in the ‘Huayu 22’ in the rubisco activity. Compared with the CK, the number of chloroplasts remained unchanged, the number of grana and lamella in grana increased, and the individual chloroplast was longer and in perfect development in the functional leaves of plants of the ‘Huayu 22’ grown in the 50% NLI treatment. In contrast, the number of chloroplasts, grana and starch grains of the ‘Huayu 22’ plants decreased significantly, the chloroplast membrane and grana lamella were damaged, the number of granum lamella increased, and the individual chloroplast became longer in the 15% NLI treatment. The number and ultrastructure of chloroplasts in the ‘Baisha 1016’ plants followed similar patterns of changes as those of the ‘Huayu 22’ in the 50% NLI treatment. For plants of the ‘Baisha 1016’ in the 15% NLI treatment, their chloroplasts became more roundly shaped, with decreasing number of grana lamella and increasing number of starch grains, compared with the CK. There were a greater decrease in the grana number and more damage in the grana lamella in plants of the ‘Baisha 1016’ than those of the ‘Huayu 22’. In conclusion, the shade tolerance of the ‘Huayu 22’ resulted from lack of changes in rubisco activity and less damage in the ultrastructure of chloroplasts when under low light stress compared with the ‘Baisha 1016’.

    The role of chitosan in polyphenols accumulation and induction of defense enzymes in Pinus koraiensis seedlings
    LIU Ran, WANG Zhen-Yu, LI Ting-Ting, WANG Fang, and AN Jing
    Chin J Plan Ecolo. 2014, 38 (7):  749-756.  doi:10.3724/SP.J.1258.2014.00070
    Abstract ( 419 )   PDF (439KB) ( 687 )   Save
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    Aims This study aimed to explore the physiological mechanisms of polyphenols synthesis promoted by chitosan elicitor in Pinus koraiensis.
    Methods Pinus koraiensis seedlings were cultured for eight days under different chitosan concentrations in the DCR media and the accumulations of polyphenols and proanthocyanidins were measured, in order to determine the chitosan concentration for optimal polyphenols accumulation. The changes in polyphenols accumulation, activities of defense enzymes, and activities of key enzymes for polyphenol synthesis were then studied in P. koraiensis seedlings under the optimal chitosan concentration.
    Important findings Results showed that chitosan at the concentration ranging from 50 to 200 mg·L–1 effectively increased the accumulation of polyphenols and proanthocyanidins in P. koraiensis seedlings. The effect of induction by chitosan reached the peak at 100 mg·L–1. The polyphenols accumulation in P. koraiensis seedlings treated with chitosan reached (9.91 ± 0.68) mg·g–1 in fresh mass, which was 1.64 times the content in the control. The accumulation of proanthocyanidins reached (2.52 ± 0.11) mg·g–1 in fresh mass, which was 1.53 times the accumulation in the control. Activities of defense-related enzymes (superoxide dismutase, peroxidase, and catalase) and polyphenol biosynthesis-related enzymes (phenylalanine ammonia-lyse, and cinnamate-4-hydroxylase) in P. koraiensis seedlings were increased significantly by chitosan elicitor at the concentration of 100 mg·L–1. Chitosan could significantly activate defensive response and the phenylpropanoid pathway in P. koraiensis, thus promoting the synthesis and accumulation of polyphenols and enhancing the resistance of P. koraiensis seedlings.

    Effects of supplemental irrigation by measuring the moisture content at jointing and anthesis on fluorescence characteristics and water use efficiency in flag leaves of wheat
    GUO Zeng-Jiang, YU Zhen-Wen, SHI Yu, ZHAO Jun-Ye, and ZHANG Yong-Li
    Chin J Plan Ecolo. 2014, 38 (7):  757-766.  doi:10.3724/SP.J.1258.2014.00071
    Abstract ( 532 )   PDF (427KB) ( 1245 )   Save
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    Aims Our objective was to determine the effects of supplemental irrigation by measuring the moisture content at jointing and anthesis on fluorescence characteristics and water use efficiency in flag leaves of wheat (Triticum aestivum).
    Methods Four irrigation treatments were imposed, i.e. the average relative soil water content in the soil layer of 0–20 cm (D1), 0–40 cm (D2), 0–60 cm (D3), and 0–40 cm (D4) were raised to 65% (at jointing) and 70% (at anthesis), respectively, by supplemental irrigation, with zero-irrigation as a control treatment (D0) in 2011–2012 and 2012–2013.
    Important findings The soil water consumption in the D2 treatment was significantly higher than in other treatments in the 40–100 cm soil layer from jointing to anthesis and in the 40–140 cm soil layer from anthesis to maturity; the latter stage showed the highest soil water consumption during wheat growing. The flag leaves of wheat plants in the D2 treatment showed the highest water use efficiency, potential photosynthesis activity of PSII (Fv/Fo), electronic transpiration activity of PSII (Fm/Fo), relative electron transport rate (ETR) and photochemistry quenching index (qP) after anthesis, followed by the D3 treatment, with those in the D0 treatment having the lowest values. In both growing seasons, the grain yield was ranked in the order of D2 > D3 > D1 > D4 > D0 among the treatments; water use efficiency (WUE) in the D2 treatment was 20.19 kg·hm–2·mm–1 and 21.92 kg·hm–2·mm–1, respectively, higher than in the D0, D3, and D4 treatments. No significant difference was observed in any of the variables between the D1 and D2 treatments. Hence, the D2 treatment, with application of irrigation based on the soil moisture measurement in the 0–40 cm soil layer at jointing and anthesis, is the most optimal treatment for achieving high grain yield and high WUE.

    Effects of tillage and nitrogen addition rate on nitrogen metabolism, grain yield and protein content in wheat in lime concretion black soil region
    XIONG Shu-Ping, WANG Jing, WANG Xiao-Chun, DING Shi-Jie, and MA Xin-Ming
    Chin J Plan Ecolo. 2014, 38 (7):  767-775.  doi:10.3724/SP.J.1258.2014.00072
    Abstract ( 483 )   PDF (366KB) ( 972 )   Save
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    Aims The purpose of this study was to determine a suitable combination of tillage method and nitrogen rate to improve wheat (Triticum aestivum) yield and protein content in lime concretion black soil.
    Methods Under the field experimental conditions, three tillage methods (subsoiling and rotary tillage, rotary tillage, and conventional tillage) were used as the main treatments, and four nitrogen application rates (0, 120, 225 and 330 kg·hm–2) were used as sub-treatments. Nitrogen assimilation after jointing stage, grain yield, and protein content were determined in wheat plants to study the effects of different tillage methods and nitrogen application rate on these variables.
    Important findings Results showed that the glutamine synthetase (GS) activity, free amino acid content, and soluble protein content in wheat plants initially increased and then decreased during growth. The peaks of GS activity, free amino acid content, and soluble protein content occurred 10 days after flowering in the subsoiling treatment with 225 or 330 kg·hm–2 nitrogen application rate, and at the flowering stage for other treatment combinations. Compared with the conventional tillage and rotary tillage, the bulk density of 10 to 40 cm soil in the subsoiling treatment was significantly reduced, and the soil total porosity and root dry weight were significantly increased. Tillage method and nitrogen application rate had a significant impact on grain yield and protein content in wheat plants. Grain yield and protein content were highest in the subsoiling treatment. Regardless of the tillage method, the grain yield and protein content both increased with increasing nitrogen application rate. The grain yield in the subsoiling treatment was highest with nitrogen application rate at 330 kg·hm–2, whereas the outputs of conventional tillage and rotary tillage were peaked at nitrogen application rate of 225 kg·hm–2. The grain protein content was highest at nitrogen application rate of 225 kg·hm–2 under the three tillage methods. Thus, subsoiling with optimum nitrogen rate should be promoted in lime concretion black soil. Subsoiling increased grain yield and protein quality by improving soil conditions and the absorption of root systems for soil nitrogen.

    Effects of atmospheric CO2 enrichment on phloem sap composition and root nitrogen accumulation in oilseed rape
    YANG Chun, TAN Tai-Long, YU Jia-Ling, LIAO Qiong, ZHANG Xiao-Long, ZHANG Zhen-Hua, SONG Hai-Xing, and GUAN Chun-Yun
    Chin J Plan Ecolo. 2014, 38 (7):  776-784.  doi:10.3724/SP.J.1258.2014.00073
    Abstract ( 371 )   PDF (375KB) ( 1019 )   Save
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    Aims The rising global atmospheric CO2 concentration has become an indisputable fact. It will like to impose significant impacts crops. Our objective was to study the effects of elevated CO2 concentration on soluble sugars and free amino acids in the phloem sap and nitrogen (N) accumulation in roots.
    Methods Two oilseed rape (Brassica napus) varieties, ‘814’ and ‘Xiangyou 15’, were chosen in this study, and the soluble sugars and free amino acids in the phloem sap and nitrogen accumulation in roots were measured under two CO2 concentrations (normal: 400 μmol·mol–1, elevated: (800 ± 20) μmol·mol–1) and two N application levels (without N application, normal N application).
    Important findings The result shows that: 1) Soluble sugars in the phloem of oilseed rape were increased in the elevated CO2 treatment. With N application, the soluble sugar content reached 0.29% in ‘814’ at the bolting stage, and reached 0.25% in ‘Xiangyou 15’ at the flowering stage; both genotypes had greater soluble sugar content under elevated CO2 concentration and under the normal CO2 treatment. 2) Free amino acids in the phloem of oilseed rape were reduced by elevated CO2 treatment with or without N application in ‘814’. In the treatment without N application, the free amino acids in the phloem of ‘Xiangyou 15’ were increased by 1.87%, 40.43%, 11.01%, and 224.90% under elevated CO2 at seedling stage, bolting stage, flowering stage, and silique stage, respectively; Whilst with normal N application, the percentage of increases was as high as 7.17%, 29.73%, 15.13%, and 5.38%, respectively. 3) Dry weight and N accumulation of roots were increased by elevated CO2 treatment. It is demonstrated that the soluble sugars and free amino acids in phloem are positively related to the dry weight and N accumulation of roots.

    Growth vigour and yield of transgenic RRM2 (RNA recognition motif 2) cotton and their effects on arthropod community in cotton field
    LUO Jun-Yu, LIU Chuan-Liang, ZHANG Shuai, WANG Chun-Yi, Lü Li-Min, LI Chun-Hua, LI Fu-Guang, and CUI Jin-Jie
    Chin J Plan Ecolo. 2014, 38 (7):  785-794.  doi:10.3724/SP.J.1258.2014.00074
    Abstract ( 486 )   PDF (307KB) ( 647 )   Save
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    Aims This experiment was carried out to assess the breeding value of the transgenic RRM2 (RNA recognition motif 2) cotton and to evaluate its environmental safety on cotton field.
    Methods The indices of structure and composition, community characteristics, biodiversity, species richness and the seasonal changes of the arthropod community in transgenic RRM2 cotton field and the parental conventional cotton field were studied systematically in 2012 and 2013, respectively. We also analyzed the climate data from June to September of the two years, and compared the cotton growth vigour and the yield parameters between the transgenic cotton and the non-transgenic cotton.
    Important findings The results showed that there were no significant differences in the indices of structure and composition, biodiversity, evenness, dominant concentration and the seasonal changes of insect communities and sub-communities between the transgenic cotton field and the non-transgenic cotton field within the same years. Comparing with in 2012, all the indices of arthropod communities and cotton growth vigour and cotton yield parameters in 2013 showed an overall downward trend in both the transgenic and the non-transgenic cotton fields. The dynamics of functional groups of dominant natural enemies lagged behind that of the dominant pests both in the transgenic cotton field and the non-transgenic cotton field, indicating a need to control the pests at the early stage of cotton growth.


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