Li Pingping

Comparison of carbonic anhydrase activity among various species of plantlets

During plant tissue culture, the culture container is small and sealed; the concentration of CO2 in the microenvironment is relatively low. The plantlet growth is restrained for the shortage of CO2 in the culture container. Carbonic anhydrase is a zinc-containing metalloenzyme that catalyzes the reversible conversion of bicarbonate to CO2. The determination of carbonic anhydrase of leaves from Atractylodes lancea (thunb.) DC, Orychophragmus violaceus (L.) O.E. Schulz, Brassica juncea (L.) Czern.et Coss. cv. Luzhousileng, Brassica campestris L. cv. Chuanyou No.8, Brassica napus L cv. Oro, Brassica carinata Braun, Raphanus sativa L. var. raphanistroides Makino and their plantlets indicates that the carbonic anhydrase activity of leaves from both plantlets and fields varies from plant species to plant species, the carbonic anhydrase activity of leaves of Atractylodes lancea (thunb.) DC is the lowest among those plants, and the leaves of all plantlets are lower in carbonic anhydrase activity than the same species of plants from fields. The comparison of the growth rates of those plantlets shows that their relative growth rates are significantly different, plantlets of Atractylodes lancea have the slowest relative growth rate among those plants, and plantlets of Brassica juncea have the greatest relative growth rate. The relationship between RGR of plantlets and their CA activities is a significant linear function. It seems that there was certain correlation between carbonic anhydrase activities of plants and their growth rates. It suggests that in vitro, the greater the carbonic anhydrase activity of plantlet is, the higher its net photosynthetic rate, and the faster its growth rate. Those results offer a foundation to a rational medium choice in plant tissue culture.

Doppler frequency parameters estimation for SAR imaging using a modified discrete chirp-Fourier transform

The key technology of high resolution radar image is to precisely estimate the Doppler parameters. The discrete chirp-Fourier transform (DCFT) proposed recently is an effective technique for chirp signal detection. But it requires some rigorous restriction on the signal length and parameters, which restricts the application of DCFT to the engineering fields. The paper advanced a novel modified discrete chirp-Fourier transform (MDCFT) to overcome the restriction, this new transform can make the signal energy concentrate in the transform domain to precisely estimate the parameters. The simulation SAR imaging based on the MDCFT proves that the new algorithm is more practical and effective.

Study on the Number and Placement for Moisture Monitoring Sensor in Lettuce with Substrate Cultivation

A continuous monitoring tests for substrate moisture content were carried out in different depths of lettuce field under drip irrigation in greenhouse. Based on the observation data of the moisture probes laid at fixed points, the correlationship between substrate water content in different depths were analyzed, a better method for installing water monitoring points in substrate profile under drip irrigation is selected by R type hierarchical clustering method. Comprehensive analysis the substrate physical properties and the activity root zone of lettuce showed that the moisture sensors buried in 5 and 15 cm for monitoring the substrate moisture content in the depths of 0~15 cm were reasonable.

Study on Modeling Virtual Plant Development Process Based on Growth Model

It is important to establish the virtual plant model for digital agriculture complying with the law of plant development. Through large numbers of experimental data during the plant development, using the accumulated growth day as parameter, the morphological and physiological models would be found accordingly. Defining the plant growth unit and its organs with the way of type seal technology, the description which expresses the plant development changes consisting of topological structure and organ morphology can be obtained, then the virtual plant growth model could be constructed based on the information fusion and reconstruction. The experiments demonstrated the presented model was effective and feasible when simulating plant development, which also showed valuable evidences in managing and predicting the environmental conditions suitable to plant growth.

Solar energy utilisation efficiency in environment-controlled agriculture in China

In the light of an analysis of the solar radiation and temperature resources in different part of China, this paper classifies Environment-Controlled Agriculture (ECA) in China into zones and briefly introduces the feature of each zone. Meanwhile, features of different ECA types such as heliogreenhouse, plastic arched shed, adumbral net and their contributions to increasing solar energy utilisation efficiency are analysed. On the basis of the above analysis, possible technical ways to increase potential production of ECA are put forward.