Disparities in tree mortality among plant functional types(PFTs)in a temperate forest:Insights into size-dependent and PFT-specific patterns

Tree mortality significantly influences forest structure and function,yet our understanding of its dynamic patterns among a range of tree sizes and among different plant functional types(PFTs)remains incomplete.This study analysed size-dependent tree mortality in a temperate forest,encompassing 46 tree species and 32,565 individuals across different PFTs(i.e.,evergreen conifer vs.deciduous broadleaf species,shade-tolerant vs.shade-intolerant species).By employing all-subset regression procedures and logistic generalized linear mixed-effects models,we identified distinct mortality patterns influenced by biotic and abiotic factors.Our results showed a stable mortality patte rn in eve rgreen conifer species,contrasted by a declining pattern in deciduous broadleaf and shadetolerant,as well as shade-intolerant species,across size classes.The contribution to tree mortality of evergreen conifer species shifted from abiotic to biotic factors with increasing size,while the mortality of deciduous broadleaf species was mainly influenced by biotic factors,such as initial diameter at breast height(DBH)and conspecific negative density.For shade-tolerant species,the mortality of small individuals was mainly determined by initial DBH and conspecific negative density dependence,whereas the mortality of large individuals was subjected to the combined effect of biotic(competition from neighbours)and abiotic factors(i.e.,convexity and pH).As for shade-intolerant species,competition from neighbours was found to be the main driver of tree mortality throughout their growth stages.Thus,these insights enhance our understanding of forest dynamics by revealing the size-dependent and PFT-specific tree mortality patterns,which may inform strategies for maintaining forest diversity and resilience in temperate forest ecosystems.

Identification and Analysis of Mature Plant Type Mutants of M_1 Generation Foxtail Millet Changnong35 Treated with EMS Mutagenesis

[Objective] The aim was to identify the mutants of millet Changnong35 induced by different concentrations of EMS, so as to construct a millet mutant library. [Method] Foxtail millet cultivar Changnong35 which is widely used in agricultural production, was treated with 0.8% and 1.0% EMS; and then seven traits of mutants were investigated analyzed, to classify the mutants into different groups. [Result] 282 mutants in the M1 generation related to plant type were obtained, of which, 100 mutant plants treated with 0.8% EMS can be divided into 10 groups; 182 mutant plants obtained by using 1.0% EMS can be divided into 17 groups. The analysis results of the mature plant type traits of the M1 Generation showed that, plant height, diameter of stem under spike, diameter of the first internode under spike and internode number of the mutants treated with 1.0% EMS were significantly different from those of control, while those of mutants treated with 0.8% EMS did not show significant difference from those of control. [Conclusion] The inducing with 1.0% EMS was more conducive to obtain a large number and different types of mutants from Changnong35.

The unimodal latitudinal pattern of K,Ca and Mg concentration and its potential drivers in forest foliage in eastern China

Potassium(K),calcium(Ca),and magnesium(Mg)are essential elements with important physiological functions in plants.Previous studies showed that leaf K,Ca,and Mg concentrations generally increase with increasing latitudes.However,recent meta-analyses suggested the possibility of a unimodal pattern in the concentrations of these elements along latitudinal gradients.The authenticity of this unimodal latitudinal pattern,however,requires validation through large-scale field experimental data,and exploration of the underlying mechanisms if the pattern is confirmed.Here,we collected leaves of common species of woody plants from 19 montane forests in the north-south transect of eastern China,including 322 species from 160 genera,67 families;and then determined leaf K,Ca,and Mg concentrations to explore their latitudinal patterns and driving mechanisms.Our results support unimodal latitudinal patterns for all three elements in woody plants across eastern China,with peak values at latitude 36.5±1.0°N.The shift of plant-functional-type compositions from evergreen broadleaves to deciduous broadleaves and to conifers along this latitudinal span was the key factor contributing to these patterns.Climatic factors,mainly temperature,and to a lesser extent solar radiation and precipitation,were the main environmental drivers.These factors,by altering the composition of plant communities and regulating plant physiological activities,influence the latitudinal patterns of plant nutrient concentrations.Our findings also suggest that high leaf K,Ca,and Mg concentrations may represent an adaptive strategy for plants to withstand water stress,which might be used to predict plant nutrient responses to climate changes at large scales,and broaden the understanding of biogeochemical cycling of K,Ca,and Mg.

Comparative Analysis on Rice Plant Type of Two Super Hybrids and Shanyou63

The characteristics of plant type and physiological indices for photosynthesis were analyzed using two super hybrid rices, Liangyoupeijiu and LiangyouE32 as materials, and an indica hybrid, Shan-you63 as a control. Based on the present analysis and various theories and breeding practices on rice plant type, a model of plant ideotype for super hybrid rice (indica) in the lower reaches of Yangtze River Valley was proposed. This was: a length of 35 - 40 cm for top leaf with a width of 2 cm, and that of 50 - 55 cm and 55-60 cm, respectively, for the second and third leaves from top, meanwhile, having a leaf angle of 5°, 10°and 15° respectively, and a curvature of 1 - 1. 5 cm-1for the leaf face at heading stage; the uppermost three leaves keeping their activities for as long as 70 d, which could lead a LAI of 3 at full ripeness; loose plant type with thin (SLW=2.5-3 g cm-2, dry weight) and curve-slant leaves during early growing stage, and compact plant type by thick (SLW=4 - 5 g cm-2) and erect leaves during the middle and late growing stages; with a coefficient of light extinction of 0. 3 - 0. 4, which allowed for an optimal LAI high of 8-10 during the middle growth period; plant height of 110-120 cm, with 2 - 4 cm basal internode and a long uppermost internode occupying 45% of total stem length; 25 - 28 cm panicle with 8-10 spikelets per centimeter showing bend-type in ripening; a rich chlorophyll which led to a high net photosynthetic rate, and tolerance to light shading and photooxidation which is of benefit to increasing the adaptability to varying light conditions.

Source-sink Characteristics and the Translocation of Assi- milates in New Plant Type and Intersubspecific Hybrid Rice

Both new plant type (NPT) and intersubspecific hybrid rice (IHR) had large sink size (total number of spikelets per m2), however, poor grain filling limited their potential in the grain yield. Compared to the three-line indica hybrid of Shanyou 63 (CK), NPT and IHR showed higher photosynthetic potential, higher dry matter accumulation and higher ratio of dry weight to spikelets (total dry wt./total number of spikelets) from heading to harvest. But both exhibited a low export percentage and transfer ratio of assimilates, low partitioning of 14C to grains from labeled flag leaves, low harvest indices and low physiological activities (IAA content and activities of ATPase and starch synthase) of grains at early grain-filling stage. The physiological activities of grains at early filling stage were significantly correlated with the export percentage and transfer ratio of assimilates, ripened-grain percentage and grain plumpness (r = 0.85 - 0.95). The source-sink ratio (dry matter wt./spikelet and nonstructural carbohydrate/spikelet) at heading was positively correlated with physiological activities of grains (r = 0. 84 - 0. 97 ). It is suggested that low physiological activities of grains at early filling stage is attributed to low source-sink ratio at heading, and the low sink activity weakens the ability to remobilize assimilates into grains, and leads to poor grain filling in NPT and IHR.

Genetical and Physiological Basis of Plant Type Model of Erect and Large Panicle Japonica Super Rice in Northern China

The historical changes in rice yields across China were explored. The physiological mechanisms and genetic basis of the erect and large panicle super-high-yield plant type model for breeding japonica super rice were analyzed mainly on the panicle type, number of large vascular bundles （LVB） in the panicle neck, and the panicle type index （PTI）. In the production point of view, we suggested that, for the breeding of super-high-yield japonica rice, the erect panicle types with more LVB numbers in the panicle neck and superior upper grains in the secondary branches would be the key factors. The information has potential significance in the rice breeding and productivity not only in China but also throughout the rice production areas of the world.

Plant Type and Its Effects on Canopy Structure at Heading Stage in Various Ecological Areas for a Two-line Hybrid Rice Combination,Liangyoupeijiu

A two-line hybrid rice combination, Liangyoupeijiu, was used to estimate several factors of plant type, and environmental models for these factors at the heading stage were established using the data of eight ecological experimental sites in 2006 and 2007. According to climatic data from 1951 to 2005, the differences in those factors and their effects on plant canopy were analyzed for four rice cropping areas in China, including South China, the middle-lower reaches of the Yangtze River, Sichuan Basin, and river valley in Yunnan, China. The thickness of leaf layer （the distance from pulvinus of the third leaf from the top to the tip of flag leaf） and distribution of leaf area could be used as candidate indices for the plant type of a rice canopy.

Analysis and Simulation of Plant Type on Canopy Structure and Radiation Transmission in Rice

Three typical hybrid rice cultivars, together with three artificially modified plant types by the application of N fertilizer during the elongation of the two uppermost leaves were used to analyze how the plant type affected the layered leaf area and radiation transmission. Plant type factors, layered leaf area and radiation distribution were measured at the full heading, 10 d and 25 d after full heading stages, respectively. A model for calculating the layered leaf area from plant type factors was established and validated to determine the effects of plant type factors on the layered leaf area for the three hybrids. Furthermore, the relationship between layered leaf area and radiation transmission was established by using the radiation transmission model. The effects of the plant type factors on the radiation transmission for the three hybrids were evaluated by using this model. Finally, a method was established to describe the canopy structure, such as the layered leaf area index and the radiation distribution in the rice canopy.

Inheritance of Several Plant Type Characters in Truss Tomato

Plant type characters of truss tomato were studied for exploring the inheritance of leaf angle, and providing a theoretical basis for breeding truss tomato cultivars in compact plant type. Participant truss tomato inbred lines were involved in the cross and backcross for multi-generations, and the mixed major genes plus polygene inheritance model was employed to analyze the inheritance model of leaf angle, plant width, and leaf drooping value. The inheritance of leaf angle and plant width was controlled by one pair of additive major genes plus additive-dominant polygene （D-2）. The additive effect of the major genes controlling leaf angle was 6.51, the additive effect of the polygene was 15.01, the potential ratio was 0.914, and the dominant degree was 0; the heritability of the major genes was 45.61% in B1 generation, 37.29% in B2 generation, and 47.71% in F2 generation. The additive effect of the major genes controlling plant width was 3.08, while the additive effect and dominant effect of the polygene were 3.58 and -1.59, respectively, with the potential ratio of -0.44 and 0 dominant degree; the heritability of the major genes was 23.30% in B1 generation, 20.73% in B2 generation, and 36.11% in F2 generation; leaf-drooping-value trait was controlled by one pair of negative complete dominant major genes plus additive-dominant polygene （D-4）. The additive effect of the major genes was 8.18, the dominant effect was -8.18, the additive effect in the polygene was 3.12, the dominant effect was 19.07, the potential ratio was 6.09, and the dominant degree was -1; the heritability of the polygene was 69.15% in B1 generation, 68.5% in B2 generation, and 49.57% in F2 generation. The improvement on leaf angle and plant width of 173×101 should be focused on the major genes and the selection should be made in early generations, while the improvement on leaf-drooping-value of 173×01 should be made in late generations.

Classification of plant functional types based on the nutrition traits： a case study on alpine meadow community in the Zoigê Plateau

The ecological concept of Plant Functional Types（PFTs）, which refers to the assemblage of plants with certain functional traits, has been introduced for the study of plant responses to the environment change and human disturbance. Taking the alpine meadow community in the Zoigê Plateau as a study case, this paper classified PFTs in terms of plant nutrition traits. The sequential results are as follows.（1） The main herbages in the Zoigê Plateau included 16 species in 5 families. Among the five families, Cyperaceae vegetation accounted for 81.37%of herbage area in total, while the remaining 4families occupied less than 20%. As for the species,Kobresia setchwanensis Hand.-Maizz. was dominant,accounting for 48.74% of the total area; while the remaining 51.26% was comprised of Polygonum viviparum L., Anaphalis fiavescens Hand.-Mazz.,Stipa aliena Keng and other species.（2） By using the Principal Component Analysis（PCA）, the assessment of herbages nutrition was carried out based on the comprehensive multi-index evaluation model.Polygonum viviparum L. had the highest nutritional value score（1.43）, and Stipa aliena Keng had the lowest（-1.40）. Nutritional value of herbage species had a significantly positive correlation with altitude（P＆lt;0.01） in the Zoigê Plateau.（3） Based on the nutritional values, herbages in the Zoigê Plateau could be grouped into 3 nutrition PFTs（high, medium and low） by using the Natural Breaks（Jenks） method.

Relationship Between Plant Type and Grain Quality of Japonica Hybrid Rice in Northern China

Plant type and grain quality are two major aspects in rice breeding. Using canonical correlation analysis and canonical redundancy analysis, the relationship between plant type traits and rice grain quality traits was studied with 100 crosses derived from 10 sterile lines × 10 restorer lines. There was a complex relationship between parts of the traits of the two aspects. The angle of the 2nd leaf from the top and single panicle weight played important roles in plant type system and amylose content and grain length in grain quality system. The angle of the 2nd leaf from the top, plant height and single panicle weight had a great effect on grain quality traits, and amylose content, brown rice rate and translucency were easily influenced by plant type traits. Selection index model indicated that japonica hybrid rice in Northern China with good quality was characterized by broad flag leaf and 2nd leaf from the top, narrow and short 3rd leaf from the top, low plant height, short culm, long and more panicles and low single panicle weight.

Effects of Plant Community Type on Soil Methane Flux in Semiarid Loess Hilly Region,Central Gansu Province,China

Methane(CH_(4))is an important greenhouse gas second only to CO_(2)in terms of its greenhouse effect.Vegetation plays an important role in controlling soil CH_(4)fluxes,but the spatial variability of soil CH_(4)fluxes during vegetation restoration in Loess Hilly Region(LHR)is not fully understood.The effects of different plant community types[Medicago sativa grassland(MS);Xanthoceras sorbifolium forestland(XS);Caragana korshinskii bushland(CK);Hippophae rhamnoides shrubland(HR);and Stipa bungeana grassland(SB)]on soil CH_(4)flux in LHR were studied via the static chamber technique.The results showed that the five plant community types were sinks of soil CH_(4)in LHR,the plant community type significantly affected the soil CH_(4)flux,and the average CH_(4)uptake from high to low was in SB,HR,CK,MS,and XS.During the whole study period,the soil CH_(4)flux showed similar interannual variation.The maximum absorption of soil CH_(4)appeared in the growing season,while the minimum appeared in winter.Soil CH_(4)uptake was positively correlated with soil temperature and soil moisture.Soil temperature and moisture are important controlling factors for the temporal variability of soil CH_(4)flux.In LHR,the Stipa bungeana grassland is the more suitable plant community type for reducing soil CH_(4)emissions.In the process of vegetation restoration in LHR,the soil CH_(4)absorption potential of different plant community types should be considered,ecological benefits should be taken into account,and vegetation more suitable for mitigating the greenhouse effect should be selected.

Characterization of Growth and Light Utilization for Rice Genotypes with Different Tiller Angles

Tiller angle is very important for plant architecture and canopy structure in rice （Oryza sativa L.）. Physiological and ecological characteristics of three rice genotypes with different tiller angle habits were compared in the paper. DI508, a genotype with changing tiller angle during the growth, has semi-erect tillers at early tillering stage, similar to genotype M09, and had erect tillers at late stage, similar to genotype 9308. In terms of dry biomass per plant, DI508 was consistently higher than those of M09 and 9308 throughout the growth. It was also a distinct difference of leaf area per plant that DI508 was larger than two others. From booting stage, DI508 and 9308 maintained higher photosynthetic ability of the topmost three leaves, while M09 showed rapid decline in photosynthesis during grain filling. It may be concluded that the genotype DI508 with dynamic tiller angle habit has a comprehensive advantage of fast growth and high weed competition at early stage and slow decline in photosynthesis at late stage.

Genetic Analysis on Plant Type of Northern Japonica Hybrid Rice

This study was designed to analyze the genetic relationship of the morphological traits of the northern japonica hybrid rice. The genetic relationship of the morphological traits of the 100 cultivars combined by the 10 sterile lines and the 10 restore lines was studied by using the principle component analysis and the SAS and QGA. The results showed that compared with the female parent, most of the morphological traits related closely to their father. The additive genetic effect and the dominant genetic effect appeared significantly, and the former was more significant than the latter. Genetic correlation analysis indicated that high plants or high plants with more leaves were in favor of improving the number and the weight of the spike and producing the hybrid vigor. The important factors influencing the plant type of the northern japonica hybrid rice were the plant height （PH）, the angle of the flag leaf （FLA）, flag leaf length （FLL）, and the weight of the shoots and leaves （SLW）, respectively. The morphological traits system of the northern japonica hybrid rice was very complex, and the restore line should be given more importance compared with the sterile line, and PH, FLA, FLL, and SLW should be considered first in the plant type breeding.

Effect of Plant Type on Grain Yield of Maize Hybrid Grown in Different Densities

The grain yield variation among 18 maize crosses with the upright, medium and patulous plant type in the close, middle and thin densities was studied in Heilongjiang province. The upright crosses with leaf orientation value more than 45 and leaf length-width ratio more than 7.5 showed adaptation to close planting. The higher leaf orientation value and leaf length-width ratio of upright crosses would play their parts to yield independently only in the close density in the test (95200 plants/ha). In the thin and middle density treatments the upright crosses yield no more than medium and patulous ones.

Plant type effect overweighs seasonal variation in n-alkanoic acid biomarker on regional Loess Plateau of China

The effect of plant type on n-alkane biomarker has been widely studied,but the influence of plant type on n-alkanoic acids(n-FAs)has received less attention.Understanding the effect of the distribution of n-FAs and their hydrogen isotope composition(δ^(2)H_(FA))is critical for interpreting sedimentaryδ^(2)H_(FA)values as proxies of hydroclimate and/or vegetation changes.In this study,we systematically investigated the distribution ofn-FAs andδ^(2)H_(FA)values across seasons on the Chinese Loess Plateau(CLP).Our results showed that there were no significant seasonal differences in n-FAs distribution andδ^(2)H_(FA)values,but there were significant differences inδ^(2)H_(FA)values across plant types.Theδ^(2)H_(FA)values ranged from-185‰to-125‰in dicots(-161‰±28‰),and from-215‰to-170‰in monocots(-196‰±22‰)on the CLP.Isotope fractionation betweenδ^(2)H_(FA)values and precipitationδ^(2)H(ε_(FA-P))was also^(2)H-enriched in dicots relative to monocots.At the regional scale of the CLP,δ^(2)H_(FA)values were not correlated withδ^(2)H values of precipitation.However,δ^(2)H_(FA)values from the CLP were similar to expectations from a global comparison,both in terms of their mean values and high variability among plants growing in sites with similarδ^(2)H values of precipitation.As some of this variability inεFA-Pis due to the effect of plant type,a careful assessment of the likely sources of waxes in terrestrial sediments is critical when usingδ^(2)H_(FA)values for paleohydroclimate reconstruction.

Comparison among Growth, Photosynthesis and Yield in Nanjing 9108 and Its Parents during the Late Development Stage

A good quality, high yield, slow mature and middle season Japonica rice variety, Nanjing 9108 and its parents Guandong 194 and Wuxiangjing 14,were taken as the materials for the study. The growth and photosynthetic characteristics of the rice plants at the post-flowering stage were compared and the rice yield components were examined at harvest. The results showed that as compared with Wuxiangjing 14, the per plant yield of Nanjing 9108 was 7.70% higher, and much higher than that of Guandong194. The large total grain per plant and heavy grain weigh of Nanjing 9108 were the important structure basis for its yield. Further analysis o the growth indicators showed that Nanjing 9108 had a large leaf area of upper three green leaves area and a smaller leaf base angle in the third leaf from the bottom blades, which helped get a higher photosynthetic capacity in groups. On the14 thday after flowering, Nanjing 9108 had similar value of net photosynthetic rate（Pn） to that of Wuxianjing 14, but lower than that of Guandong 194. Viewing from the parameters obtained from light response of photosynthesis on the modified model of rectangular hyperbola, Pn of Nanjing 9108 was more aptated to be saturated by light intensity and sensitive to photoinhibition. On the whole, Nanjing 9108 with high yield mainly resulted from its good plant type, grain structure and higher photosynthetic capacity in groups. Further improving its photosynthetic capacity o single leaf in Nanjing 9108 would be an important way for its super high yield po tential in the future.

Practice and Thought on Developing Hybrid Rice for Super High Yield by Exploiting Inter-subspecific Heterosis

Since the breakthrough of grain yield owing to the development of dwarf rice and three-line system hybrid rice, rice breeding for high yield hardly had showed significant progress in the next successive two decades. It was considered that utilizing heterosis between subspecific varieties (Oryza sativa L.) would be an effective approach to increase yield further. During 1987-1993, an indica-japonica hybrid Yayou 2 yielded as high as 10.5 t/ha; however, it failed to be commercialized because of seed purity problem due to non-uniform emasculation by chemical agent in seed production, and sensitivity of seed setting in Ft plants to environmental conditions. In the past decade, two inter-subspeific hybrids, Liangyoupeijiu (Peiai 64S/9311, javanica/indica) and Liangyou E32 (Peiai 64S/E32, javanica/ laponica); both of them exhibited grain yield higher than 10.5 t/ha, and were widely judged as the pioneers of super hybrid rice. Liangyoupeijiu has been successfully popularized over 4 million hectare in wide climatic areas, while Liangyou E32 made a yield record and offered a model of plant ideotype for super hybrid rice. It was considered that in combination with plant ideotype, active physiological functions, and wide-range adaptability to ecological conditions, exploitation of indica-japonica heterosis would be the key approach for super hybrid rice breeding.

Relationship between plant canopy characteristics and photosynthetic productivity in diverse cultivars of cotton(Gossypium hirsutum L.)

Genotype and plant type affect photosynthetic production by changing the canopy structure in crops.To analyze the mechanism of action of heterosis and plant type on canopy structure in cotton(Gossypium hirsutum L.),we had selected two cotton hybrids(Shiza 2,Xinluzao 43) and two conventional varieties(Xinluzao 13,Xinluzao 33) with different plant types in this experiment.We studied canopy characteristics and their correlation with photosynthesis in populations of different genotypes and plant types during yield formation in Xinjiang,China.Canopy characteristics including leaf area index(LAI),mean foliage tilt angle(MTA),canopy openness(DIFN),and chlorophyll relative content(SPAD).The results showed that LAI and SPAD peak values were higher and their peak values arrived later,and the adjustment capacity of MTA during the flowering and boll-forming stages was stronger in Xinluzao 43,with the normal-leaf,pagoda plant type,than these values in other varieties.DIFN of Xinluzao 43 remained between0.09 and 0.12 during the flowering and boll-forming stages,but was lower than that in the other varieties during the boll-opening stage.Thus,these characteristics of Xinluzao 43 were helpful for optimizing the light environment and maximizing light interception,thereby increasing photosynthetic capability.The photosynthetic rate and photosynthetic area were thus affected by cotton genotype as changes in the adjustment range of MTA,increases in peak values of LAI and SPAD,and extension of the functional stage of leaves.Available photosynthetic area and canopy light environment were affected by cotton plant type as changes in MTA and DIFN.Heterosis expression and plant type development were coordinated during different growth stages,the key to optimizing the canopy structure and further increasing yield.