Monitoring Method of Total Seed Mass in a Vibrating Tray Using Artificial Neural Network.

To maintain the continuous working performance of a vacuum plate seeder, it is important to monitor the total seed mass in the seed tray in real time and accurately control the pickup position of the suction plate accordingly. Under the excitation of reciprocating vibration varying with time and interference by direction angle, the motion of seeds in a rectangular tray was simulated using the discrete element method (DEM). A measurement method for seed mass in a small area was proposed based on the impulse theorem. The impact force of seeds was monitored with a cantilever force sensor, and the corresponding signal processing circuit was designed. Calibration results indicated that the relative nonlinear error was less than 2.3% with an average seeds-mass-per-unit-area (SMA) of 0.3⁻2.4 g/cm². Then, four sets of force sensors were installed symmetrically near the four corners of the vibrating tray which were used to measure the SMA respectively. Back propagation (BP) neural networks which take four SMA measurement results as input parameters were developed to monitor the total seed mass in the tray. Monitoring results using DEM simulation data showed that the general relative error was 3.0%. Experiments were carried out on a test-rig and the results validated that the relative error was reduced to 5.0% by using the BP neural network method.

[Metabolism and interaction of C and N in the arbuscular mycorrhizal symbiosis].

The arbuscular mycorrhiza (AM) is the symbiont formed by the host plant and the arbuscular mycorrhizal fungi (AMF). The transfer and metabolism of C and N in the symbiosis plays an important role in keeping nutrient balance and resource reallocation between the host plant and the fungi. The carbohydrates produced by plant photosynthesis are transferred to the fungi, where they are metabolized as materials and energy used for fungal spore germination, mycelium growth and uptake of nitrogen and other nutrients. At the same time, N is transferred and reallocated from the fungi to the host plant, where the final released ammonium is used for plant growth. Accordingly, we reviewed the current progress in C and N transfer and metabolism in the AM symbiosis, and the crosstalk between them as well as some key issues to elucidate the mechanism of the interaction between C and N transport in the symbiosis, so as to provide the theory foundation for the application of AM in sustainable agriculture and ecosystem.

Red ginseng protects against gentamicin-induced balance dysfunction and hearing loss in rats through antiapoptotic functions of ginsenoside Rb1.

The authors evaluated the protective effects of Korean red ginseng (KRG) against gentamicin (GM)-induced unilateral vestibular and hearing dysfunction and investigated its effective mechanism using in vitro cell cultures. Vestibular function was comprehensively evaluated by a scoring system that ranged from 0 (normal) to 3 (worst) points, using head tilt, tail hanging, and swimming tests. The GM group showed significantly more deteriorated vestibular function (0 point--5 rats, 1 point--1 rat, 2 points--3 rats, and 3 points--3 rats) than the KRG+GM group (0 point--9 rats and 1 point--1 rat) (p<0.01). The hearing thresholds were better in the KRG+GM group than in the GM group (p<0.05). Quantitative analysis of hair cell damage in the scanning electron microscopy was closely related with vestibular and hearing functional results. In vitro study showed that ginsenoside Rb1 (gRb1) attenuated reactive oxygen species production, suppressed JNK activation, up-regulated Bcl-xL and down-regulated Bax, cytochrome c, caspase 3, and cleaved poly (ADP-ribose) polymerase in GM-treated VOT-E36 cells. These findings suggest that KRG including gRb1 component protects against vestibular/hearing dysfunction by inhibiting apoptotic pathways when ototoxicity is induced by unilateral intratympanic injection with GM in rats.

Differences in the arbuscular mycorrhizal fungi-improved rice resistance to low temperature at two N levels: aspects of N and C metabolism on the plant side.

We performed an experiment to determine how N and C metabolism is involved in the low-temperature tolerance of mycorrhizal rice (Oryza sativa) at different N levels and examined the possible signaling molecules involved in the stress response of mycorrhizal rice. Pot cultures were performed, and mycorrhizal rice growth was evaluated based on treatments at two temperatures (15 °C and 25 °C) and two N levels (20 mg pot(-1) and 50 mg pot(-1)). The arbuscular mycorrhizal fungi (AMF) colonization of rice resulted in different responses of the plants to low and high N levels. The mycorrhizal rice with the low N supplementation had more positive feedback from the symbiotic AMF, as indicated by accelerated N and C metabolism of rice possibly involving jasmonic acid (JA) and the up-regulation of enzyme activities for N and C metabolism. Furthermore, the response of the mycorrhizal rice plants to low temperature was associated with P uptake and nitric oxide (NO).

[Nitrogen metabolism and translocation in arbuscular mycorrhizal symbiote and its ecological implications].

Arbuscular mycorrhizal fungi (AMF) can form mutually beneficial relations with more than 80% of vascular plants, and the existence of the symbiote is of significance in promoting the growth and stress tolerance of host plants. AMF can obtain the photosynthate carbohydrates from host plants, and in the meantime, effectively promote the nitrogen (N) uptake by host plants via the absorption of various N sources by mycorrhiza mycelia, resulting in the N exchange at population or community level, the improvement of host plants nutrition and metabolism, and the strengthening of the stress tolerance of host plants. However, there are still in debates in which ways the symbiote absorbs and transfers N and what the mechanisms the N metabolism and translocation from AMF to host plants. This paper reviewed the mechanisms of N metabolism and translocation in the symbiote and the effects of carbon and phosphorous on the N metabolism and translocation. The roles of AMF in the N allocation in host plants and the related ecological significance at community and ecosystem levels were briefly elucidated, and some issues to be further studied on the N metabolism in the symbiote were addressed.