Indica hybrid rice (Oryza sativa) production aims to achieve two crucial targets: high yield and good taste.  This study selected three types of indica hybrid rice according to grain yield and taste value, including high yield and good taste (HYGT), low yield and good taste (LYGT), and high yield and poor taste (HYPT), to analyze yield components, corresponding growth characteristics, and rice taste quality.  When values were averaged across varieties and years, there were almost no differences in taste value between HYGT and LYGT; HYGT showed a significant increase in yield, owing to a higher number of panicles and spikelets per panicle, with a respective increment of 16.2 and 20.6%.  The higher grain yield of HYGT compared with LYGT was attributed to three key factors: a higher leaf area index (LAI) during heading, a higher ratio of grain to leaf, and a higher biomass accumulation at maturity.  HYGT and HYPT achieved similar high yields; however, HYGT had more panicle numbers and lower grain weight.  In addition, HYGT showed a significantly higher taste value than HYPT, attributed to its significantly lower protein and amylose contents, with reductions of 8.8 and 15.7%, respectively.  Lower protein and amylose contents might be caused by a proper matter translocation from vegetative organs to panicle.  This study suggested that reasonable panicle characteristics and translocation efficiency from vegetative organs to panicle during heading to maturity are the key factors in balancing yield and rice taste quality.  These results will provide valuable insights for rice breeders to improve the grain yield and quality of indica hybrid rice.

Although studies on the balance between yield and quality of japonica soft super rice are limited, they are crucial for super rice cultivation.  In order to investigate the effects of nitrogen application rate on grain yield and rice quality, two japonica soft super rice varieties, Nanjing 9108 (NJ 9108) and Nanjing 5055 (NJ 5055), were used under seven N levels with the application rates of 0, 150, 187.5, 225, 262.5, 300, and 337.5 kg ha^–1.  With the increasing nitrogen application level, grain yield of both varieties first increased and then decreased.  The highest yield was obtained at 300 kg ha^–1.  The milling quality and protein content increased, while the appearance quality, amylose content, gel consistency, cooking/eating quality, and rice flour viscosity decreased.  Milling was significantly negatively related with the eating/cooking quality whereas the appearance was significantly positively related with cooking/eating quality.  These results suggest that nitrogen level significantly affects the yield and rice quality of japonica soft super rice.  We conclude that the suitable nitrogen application rate for japonica soft super rice, NJ 9108 and NJ 5055, is 270 kg ha^–1, under which they obtain high yield as well as superior eating/cooking quality.

In this paper, the many indices used in validation of crop models, such as RMSE (root mean square errors), Sd (standard error of absolute difference), da (mean absolute difference), dap (ratio of da to the mean observation), r (correlation), and R2 (determination coefficient), are compared for the same rice architectural parameter model, and their advantages and disadvantages are analyzed. A new index for validation of crop models, dap between the observed and the simulated values, is proposed, with dap<5% as the suggested standard for precision of crop models. The different kinds of validation methods in crop models should be combined in the following aspects: (1) calculating da and dap; (2) calculating the RMSE or Sd; (3) calculating r and R2, at the same time, plotting 1:1 diagram.

To quantify the relationships between rice plant architecture parameters and the corresponding organ biomass, and to research on functional structural plant models of rice plant, this paper presented a biomass-based model of aboveground architectural parameters of rice (Oryza sativa L.) in the young seedling stage, designed to explain effects of cultivars and environmental conditions on rice aboveground morphogenesis at the individual leaf level. Various model variables, including biomass of blade and blade length, were parameterized for rice based on data derived from an outdoor experiment with rice cv. Liangyou 108, 86You 8, Nanjing 43, and Yangdao 6. The organ dimensions of rice aboveground were modelled taking corresponding organ biomass as an independent variable. Various variables in rice showed marked consistency in observation and simulation, suggesting possibilities for a general rice architectural model in the young seedling stage. Our descriptive model was suitable for our objective. However, they can set the stage for connection to physiological model via biomass and development of functional structural rice models (FSRM), and start with the localized production and partitioning of assimilates as affected by abiotic growth factors. The finding of biomass-based rice architectural parameter models also can be used in morphological models of blade, sheath, and tiller of the other stages in rice life.