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.

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.

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.

Plant community and ecological analysis of woodland vegetation in Metema Area,Amhara National Regional State,Northwestern Ethiopia

We studied woodland vegetation in broad-leaved deciduous woodlands of Metema in northwestern Amhara regional state, Ethiopia to determine plant community types and species distribution patterns and their relationships with environmental variables, including altitude, pH, cation exchange capacity, electrical conductivity （EC）, and moisture. We used a selective approach with a systematic sampling design. A total of 74 quadrats, each 25m × 25m at intervals of 150-200 m were sampled along the established transect lines. For herbaceous vegetation and soil data collection, five subquadrats each lm x lm were established at the four corners and the center of each quadrat. Three community types were identified using TWINSPAN analysis. All three community types showed high diversity （Shannon-Weiner index）, the highest in community type II at 3.55. The highest similarity coefficient was 0.49 （49%） between community types II and III, reflecting 0.51 （51%） dissimilarity in their species richness. The canonical correspondence ordination diagram revealed that the distribution pattern of community type I was explained by moisture while that of community types III and II was explained by EC and altitude and moisture, respectively. Altitude was the most statistically significant environmental variable, followed by moisture and EC in determining the total variation in species composition and distribution patterns while pH and cation exchange capacity were non significant. In conclusion, we recommend that any intervention should take into account these three discrete community types and their environmental settings to make the intervention more successful.

Performance and Analysis of a Model for Describing Layered Leaf Area Index of Rice

Layered leaf area index （LAIk） is one of the major determinants for rice canopy. The objective of this study is to attain rice LAI k using morphological traits especially leaf traits that affected plant type. A theoretical model based on rice geometrical structure was established to describe LAI k of rice with leaf length （Li）, width （Wi）, angle （Ai）, and space （Si）, and plant pole height （H） at booting and heading stages. In correlation with traditional manual measurement, the model was performed by high R2-values （0.95-0.89, n=24） for four rice hybrids （Liangyoupeijiu, Liangyou E32, Liangyou Y06, and Shanyou 63） with various plant types and four densities （3 750, 2 812, 1 875, and 1 125 plants per 100 m2） of a particular hybrid （Liangyoupeijiu）. The analysis of leaf length, width, angle, and space on LAI k for two hybrids （Liangyoupeijiu and Shanyou 63） showed that leaves length and space exhibited greater effects on the change of rice LAI k . The radiation intensity showed a significantly negative exponential relation to the accumulation of LAI k , which agreed to the coefficient of light extinction （K）. Our results suggest that plant type regulates radiation distribution through changing LAI k . The present model would be helpful to acquire leaf distribution and judge canopy structure of rice field by computer system after a simple and less-invasive measurement of leaf length, width, angle （by photo）, and space at field with non-dilapidation of plants.

Quantitative analysis of the effect of the PAY1 gene on rice canopy structure during different reproductive stages

The leaf and stem types are core structural characteristics of the rice phenotype that determine the light interception ability of the canopy and directly affect crop yield.The PLANT ARCHITECTURE AND YIELD 1(PAY1)gene has been shown to alter the prostrate growth habit of wild rice and to inhibit the wild rice prostrate growth gene PROSTRATE GROWTH 1(PROG1).In this paper,the wild rice introgression line YIL55,which contains the PROG1 gene;its mutant,PAY1;and its parent,TQ,were used as test varieties to construct three-dimensional(3D)canopy structure models based on 3D digital assay technology.On this basis,quantitative analyses of the PAY1 gene and the plant leaf and stem types at the jointing,heading and filling stages were performed.Under the influence of the PAY1 gene,the plant stem and leaf angles from vertical decreased significantly;the plants were upright,with larger leaves;the culm angle changed from loose to compact;and the average tiller angle during the three key reproductive stages decreased from 44.9,28.5 and 21.3°to 17.6,8.4 and 10.5°,respectively.Moreover,the PAY1 mutant retained the PROG1 gene characteristic of exhibiting dynamic changes in the tiller angle throughout the growth period,and its culm angle changed from loose during the jointing stage to compact during the heading stage.The measurements of photosynthetically active radiation(PAR)in the canopy also showed that the mutant PAY1 allowed more PAR to reach the bottom of the canopy than the other varieties.The light-extinction coefficients for PAY1 at the jointing,heading and filling stages were 0.535,0.312 and 0.586,respectively,which were lower than those of the other two varieties.In this study,the influence of the PAY1 gene on rice canopy structural characteristics was quantitatively analyzed to provide effective canopy structure parameters for breeding the ideal plant type.

Trait-based representation of hydrological functional properties of plants in weather and ecosystem models

Land surface models and dynamic global vegetation models typically represent vegetation through coarse plant functional type groupings based on leaf form, phenology, and bioclimatic limits. Although these groupings were both feasible and functional for early model generations, in light of the pace at which our knowledge of functional ecology, ecosystem demographics, and vegetation-climate feedbacks has advanced and the ever growing demand for enhanced model performance, these groupings have become antiquated and are identified as a key source of model uncertainty. The newest wave of model development is centered on shifting the vegetation paradigm away from plant functional types(PFTs)and towards flexible trait-based representations. These models seek to improve errors in ecosystem fluxes that result from information loss due to over-aggregation of dissimilar species into the same functional class. We advocate the importance of the inclusion of plant hydraulic trait representation within the new paradigm through a framework of the whole-plant hydraulic strategy. Plant hydraulic strategy is known to play a critical role in the regulation of stomatal conductance and thus transpiration and latent heat flux. It is typical that coexisting plants employ opposing hydraulic strategies, and therefore have disparate patterns of water acquisition and use. Hydraulic traits are deterministic of drought resilience, response to disturbance, and other demographic processes. The addition of plant hydraulic properties in models may not only improve the simulation of carbon and water fluxes but also vegetation population distributions.

Temporal shifts in the explanatory power and relative importance of litter traits in regulating litter decomposition

Background:Litter traits critically affect litter decomposition from local to global scales.However,our understanding of the temporal dynamics of litter trait-decomposition linkages,especially their dependence on plant functional type remains limited.Methods:We decomposed the leaf litter of 203 tree species that belong to two different functional types(deciduous and evergreen)for 2 years in a subtropical forest in China.The Weibull residence model was used to describe the different stages of litter decomposition by calculating the time to 10%,25%and 50%mass loss(Weibull t_(1/10),t_(1/4),and t_(1/2)respectively)and litter mean residence time(Weibull MRT).The resulting model parameters were used to explore the control of litter traits(e.g.,N,P,condensed tannins and tensile strength)over leaf litter decomposition across different decomposition stages.Results:The litter traits we measured had lower explanatory power for the early stages(Weibull t_(1/10)and t_(1/4))than for the later stages(Weibull t_(1/2)and MRT)of decomposition.The relative importance of different types of litter traits in influencing decomposition changed dramatically during decomposition,with physical traits exerting predominant control for the stages of Weibull t_(1/10)and MRT and nutrient-related traits for the stages of Weibull t_(1/4),and t_(1/2).Moreover,we found that litter decomposition of the early three stages(Weibull t_(1/10),t_(1/4),and t_(1/2))of the two functional types was controlled by different types of litter traits;that is,the litter decomposition rates of deciduous species were predominately controlled by nutrient-related traits,while the litter decomposition rates of evergreen species were mainly controlled by carbon-related traits.Conclusions:This study suggests that litter trait-decomposition linkages vary with decomposition stages and are strongly mediated by plant functional type,highlighting the necessity to consider their temporal dynamics and plant functional types for improving predictions of litter decomposition.

Study on Plant Morphological Traits and Production Characteristics of Super High-Yielding Soybean

Super high-yielding soybean cultivar Liaodou 14, soybean cultivars from Ohio in the United States, and the common soybean cultivars from Liaoning Province, China, with similar geographic latitudes and identical pod-bearing habits were used as the study materials for a comparison of morphological traits and production characteristics to provide a theoretical basis for the breeding of improved super high-yielding soybean cultivars. Using a randomized block design, different soybean cultivars from the same latitude were compared under conventional and unconventional treatments for their production characteristics, including morphological traits, leaf area index （LAI）, net photosynthesis rate, and dry matter accumulation. The specific characteristics of the super high-yielding soybean cultivar Liaodou 14 were analyzed. The results showed that the plant height of Liaodou 14 was significantly lower than that of the common cultivars from Liaoning, whereas the number of its main-stem nodes was higher than that of the cultivars from Ohio or Liaoning. A high pod density was observed in Liaodou 14 under conventional treatments. Under both conventional and unconventional treatments, the branch number of Liaodou 14 was markedly higher than that of the common cultivars from Liaoning, and its branch length and leaf inclination angle were significantly higher than those of common cultivars from Liaoning or Ohio. Only small changes in the leaf inclination angle were observed in Liaodou 14 treated with conventional or unconventional methods. Under each treatment, Liaodou 14 exhibited the lowest amplitude of reduction in SPAD values and net photosynthesis rates from the grain-filling to ripening stages; the cultivars from Ohio and the common cultivars from Liaoning exhibited more significant reductions. Liaodou 14 reached its peak LAI later than the other cultivars but maintained its LAI at a higher level for a longer duration. Under both conventional and unconventional treatments, Liaodou 14 produced a higher yield than the other two cultivars, with significant differences from the Ohio cultivars. In summary, super high-yielding soybean cultivars have several main features： suitable plant height, high pod density, good leaf structure with strong functionality, and slow leaf senescence at the late reproductive stage, which is conducive to the accumulation of dry matter and improved yield.

Simulation of Canopy Leaf Inclination Angle in Rice

A leaf inclination angle distribution model, which is applicable to simulate leaf inclination angle distribution in six heights of layered canopy at different growth stages, was established by component factors affecting plant type in rice. The accuracy of the simulation results was validated by measured values from a field experiment. The coefficient of determination （R2） and the root mean square error （RMSE） between the simulated and measured values were 0.9472 and 3.93%, respectively. The simulation results showed that the distribution of leaf inclination angles differed among the three plant types. The leaf inclination angles were larger in the compact variety Liangyoupeijiu with erect leaves than in the loose variety Shanyou 63 with droopy leaves and the intermediate variety Liangyou Y06. The leaf inclination angles were distributed in the lower range in Shanyou 63, which matched up with field measurements. The distribution of leaf inclination angles in the same variety changed throughout the seven growth stages. The leaf inclination angles enlarged gradually from transplanting to booting. During the post-booting period, the leaf inclination angle increased in Shanyou 63 and Liangyou Y06, but changed little in Liangyoupeijiu. At every growth stage of each variety, canopy leaf inclination angle distribution on the six heights of canopy layers was variable. As canopy height increased, the layered leaf area index （LAI） decreased in all the three plant types. However, while the leaf inclination angles showed little change in Liangyoupeijiu, they became larger in Shanyou 63 but smaller in Liangyou Y06. The simulation results used in the constructed model were very similar to the actual measurement values. The model provides a method for estimating canopy leaf inclination angle distribution in rice production.