[Model construction and application for nitrogen nutrition monitoring and diagnosis in double-cropping rice of Jiangxi Province, China].

The spectrometer-based nitrogen (N) nutrition monitoring and diagnosis models for double-cropping rice in Jiangxi is important for recommending precise N topdressing rate, achieving high yield, improving grain quality and increasing economic efficiency. Field experiments were conducted in Jiangxi in 2016 and 2017, involving different early rice and late rice cultivars and N application rates. Plant N accumulation (PNA) and canopy spectral vegetation indices (VIs) were measured at tillering and jointing stages with two spectrometers, i.

[Establishment and application of photosynthetic production model for double cropping rice].

In this study, we developed a model for photosynthetic production in double cropping rice by integrating the advantages in current crop models (including the models of canopy structure, canopy light distribution, canopy photosynthesis and dry matter production). The canopy light distribution and dry matter accumulation were preliminarily validated with independent field experiment datasets. The distribution of direct radiation both on a level surface and on the leaf surface within canopy, the canopy daily photosynthate and its characteristics with varying leaf area index for three typical plant types (erect both upper and lower, upper erect and lower flat, and flat both upper and lower) were quantitatively analyzed by the model.