[A simulation model for predicting the dry matter allocation in cut lily plants under effects of substrate water potential].

Dry matter allocation and translocation is the base of the formation of appearance quality of ornamental plants, and strongly affected by water supply. Taking cut lily cultivar 'Sorbonne' as test material, a culture experiment of different planting dates and water supply levels was conducted in a multi-span greenhouse in Nanjing from March 2009 to January 2010 to quantitatively analyze the seasonal changes of the dry matter allocation and translocation in 'Sorbonne' plants and the effects of substrate water potential on the dry matter allocation indices for different organs (flower, stem, leaf, bulb, and root), aimed to define the critical substrate water potential for the normal growth of the cultivar, and establish a simulation model for predicting the dry matter allocation in cut lily plants under effects of substrate water potential. The model established in this study gave a good prediction on the dry mass of plant organs, with the coefficient of determination and the relative root mean square error between the simulated and measured values of the cultivar' s flower dry mass, stem dry mass, leaf dry mass, bulb dry mass, and root dry mass being 0.96 and 19.2%, 0.95 and 12.4%, 0.86 and 19.4%, 0.95 and 12.2%, and 0.85 and 31.7%, respectively. The critical water potential for the water management of cut lily could be -15 kPa.

[Transpiration of Brassica chinensis L. in a plastic greenhouse covered with insect-proof nets in lower reaches of Yangtze River: a simulation study].

With the climate data inside and outside a plastic greenhouse as driving variables, and the greenhouse structure, insect-proof net material, and characteristic breadth and leaf area index of Brassica chinensis L. as parameters; a canopy transpiration model for greenhouse B. chinensis was established, based on Penmam-Monteith transpiration model. This established model was validated by the experimental data of independent samples in a single greenhouse. The results showed that in lower reaches of Yangtze River, the vent discharge coefficient (Cd) of greenhouse covered with 20-, 25-, and 28- mesh insect-proof nets was 0.771, 0.758 and 0.736, and the wind pressure coefficient (Cw) was 0.33, 0.37, and 0.39, respectively. The determination coefficient (R2) between the predicted and measured canopy transpiration rate for the sunny, cloudy, and overcast days in summer was 0.95, 0.91, and 0.94, root mean squared error (RMSE) was 0.018, 0.014, and 0.015 g x m(-2) x s(-1), and relative prediction error (RE) was 14.27%, 18.05%, and 15.80%, respectively, suggesting that this model could better predict the transpiration rate of B. chinensis in the plastic greenhouse covered with insect-proof nets in lower reaches of Yangtze River.

[Effects of stem numbers per ground area on the quality of standard cut Chrysanthemum morifolium in greenhouse: simulation model].

In order to understand the effects of stem numbers per ground area on the quality of standard cut Chrysanthemum morifolium, an experiment with different cultivars, different stem numbers per plant, different planting densities, and different planting dates was conducted in a greenhouse in Shanghai in 2005 and 2006. The effects of stem numbers per ground area on the canopy leaf area index and external quality of standard cut C. morifolium were quantified using the experimental data. Based on the physiological product of thermal effectiveness and PAR (PETP) the canopy absorbed, a model for predicting the effects of stem numbers per ground area on the quality of standard cut C. morifolium was developed, and validated with independent experimental data. The results showed that with the increase of stem numbers per ground area, the leaf area index increased, whereas plant height, stem diameter, leaf number, and flower diameter decreased. The model gave satisfactory predictions of the quality of standard cut C. morifolium cultivated with different stem numbers and planting density. The coefficient of determination (R2) and relative prediction error (RSE) based on the 1:1 line for fresh mass per stem, plant height, stem diameter, leaf number, flower diameter, and the number of qualified stem harvested per ground area were 0.95, 0.96, 0.94, 0.91, 0.81 and 0.97, and 16.1%, 10.1%, 12.8%, 13.4%, 15.9%, 16.1% , respectively. The model developed in this study could be used for the optimization of light and temperature management for standard cut C. morifolium cultivated with different stem numbers and planting densities in greenhouse.

[Simulation of rice canopy evapotranspiration and water use efficiency under free-air CO2 enrichment].

By using FACE system, the microclimate in rice canopy and related physiological indices were observed continuously from the elongation to the maturing stage of rice growth, and the effects of FACE on the rice canopy evapotranspiration and water use efficiency were studied and simulated with energy balance analysis. The results showed that using P-M equation to describe the quantitative relationships of rice leaf stomatal conductance with photosynthetically active radiation (PAR) and vapour pressure deficit (VPD) could better simulate rice canopy evapotranspiraton under FACE and ambient conditions. During observation period, the total water use of rice in FACE plot had a 10 mm decrease, compared with that in control plot. Considering of the 12% increase of total biomass, the water use efficiency of rice under FACE condition was increased by 12%.

[Simulation model on the formation of greenhouse sweet pepper leaf area index].

Leaf area index (LAI) is one of the most important crop parameters in photosynthesis-driving crop growth simulation model and canopy evapotranspiration simulation model, while air temperature and radiation are the important climate factors affecting crop leaf growth. In this paper, experiments with different sweet pepper (Capsicum annuum L.) cultivars and sowing dates were conducted in greenhouse to quantitatively analyze the relationships of the number of unfolding leaves per plant, the number of old leaves removed per plant, and the length of each leaf with air temperature and radiation. Based on these quantitative relationships, a leaf area simulation model for greenhouse sweet pepper was developed, and the independent experimental data were used to validate the model. The results showed that the number of unfolding leaves per plant was a positive exponential function of the product of thermal effectiveness and PAR (TEP) accumulated after emergence, and the length of each leaf was a negative exponential function of the TEP accumulated after emergence. The coefficient of determination (R2) and the root mean squared error (RMSE) between simulated and measured leaf number, leaf length, and LAI were 0.94, 0.89, and 0.93, and 3.4, 2.15, and 0.15, respectively. The model could use air temperature, radiation, planting density, and emergence date to satisfactorily predict the LAI of greenhouse sweet pepper, and supply required LAI information for the sweet pepper growth and canopy evapotranspiration simulation models.

[Quality prediction model of greenhouse standard cut chrysanthemum based on light-temperature effect].

Based on the effects of light and temperature on chrysanthemum quality and the experiments with different chrysanthemum varieties and planting dates, a quality prediction model of greenhouse standard cut chrysanthemum with the physiological product of thermal effectiveness and PAR (PTEP) as the measurement scale was developed and validated. The results showed that the predicted results, including the number of unfolding leaves, leaf area, plant height, stem diameter, internode length and flower diameter, accorded well with the observed ones, and the determination coefficient (R2) and relative prediction error (RSE) based on 1 : 1 line were 0.99, 0.98, 0.98, 0.92, 0.87 and 0.88, and 5.5%, 6.5%, 5.9%, 4.1%, 11.2%, 12.4%, respectively. This model was of high precision and practicable, which could be used in optimizing the light and temperature management for greenhouse standard cut chrysanthemum production.

[Effects of transplanting date and density on appearance quality of greenhouse single-flower cut chrysanthemum].

Transplanting date and density are the important factors affecting the appearance quality of chrysanthemum. The study on the greenhouse single-flower cut chrysanthemum (Chrysanthemum morifolium cv. Shenma) showed that within the ranges of test transplanting date and density, the plant height and neck length increased, while the leaf number per plant, stem diameter, plant fresh mass and flower diameter decreased with the delay of transplanting date and the increase of transplanting density. No effect of transplanting density was observed on plant height. For the production of single-flower cut chrysanthemum in non-heated greenhouse in Shanghai, the optimal transplanting date and density to achieve the top rank of quality (rank A) were the middle ten days of August and 64 plants x m(-2), and those to achieve the second rank of quality (rank B) were from mid August to early September and 72-80 plants x m(-2), respectively. The results obtained in this study offered references in establishing the prediction model of greenhouse single-flower cut chrysanthemum appearance quality based on light, temperature, and transplanting date and density.