利用内部信息的农用自动引导行走车的研究(第1报)——日本的研究现状及本研究的方法概述

从介绍农业机器人入手,对自动引导行走系统的研究及在农业领域的应用进行论述,重点说明了农业领域在该研究方面所具有的特殊性。概述了此项研究使用的方法。     

水稻短根的遗传分析

 用水稻短根突变化RM1、RM2与原品种Ohchikara杂交配成两个组合的P₁、 P₂、 F₁、 F₂、 B₁₁、B'₁₁、B₁₂、 B'₁₂ 以及F₃世代，调查冠根长度，研究短根性状的遗传。结果表明，RM1和RM2的短根性状均受单个位点稳性核基因（srt1srt1），并且RM1和RM2的短根基因是等位的。讨论了srt1基因在杂交稻和中子纯度快速鉴定中的应用。     

Temporal and spatial dynamics of begomovirus disease in tomatoes in central Brazil

Over the last two decades, begomovirus diseases have increased in importance in Brazilian tomato crops. The major management strategy in Brazil is the application of insecticides to control the whitefly vector, but this is often unsuccessful. The objective of this work was to study the spatial and temporal progression of the disease in two processing tomato production areas in Central Brazil. A total of 24 plots (225 plants each) in six fields were evaluated weekly by visual inspection for plants with begomovirus symptoms. The predominant begomovirus in tomato plants with symptoms was Tomato severe rugose virus, and it was also detected in weeds and other crop plants. No correlation between incidence of begomovirus disease and whitefly population was found. The disease progression was rapid, with a slightly aggregated distribution of plants with symptoms. No relevant differences were observed in the temporal and spatial analyses, although an important difference was detected between plots located at the centre (PC) and the edge (PE) of the fields. In the temporal analysis, the begomovirus incidence and area under disease progress curve values were lower in PC than in PE. In the spatial analysis, plants with begomovirus symptoms were more aggregated in PC than in PE. These results suggest that the distribution of plants with symptoms in PC and PE could be a result of three dissemination mechanisms: one random (primary) and two aggregated, a real secondary spread, and a false secondary spread. The implications of these differences on disease management are discussed.     

Plant growth inhibitory activity and active substances with allelopathic potential of cogongrass (Imperata cylindrica) rhizome

Cogongrass (Imperata cylindrica [L.] Raeusch.) is a perennial rhizomatous grass that belongs to the Poaceae and is widely distributed in tropical, subtropical and temperate regions over the world. The grass is strongly invasive and is suggested to have allelopathic potential. However, limited information is available on allelopathic substances in cogongrass rhizomes. Therefore, the allelopathic potential and substances in cogongrass rhizomes were investigated. The extracts of cogongrass rhizomes inhibited the root and shoot growth of barnyard grass, ryegrass, timothy, cress, lettuce and alfalfa. After bioassay‐guided separations of the extracts, four growth inhibitory substances, 5‐methoxyflavone, 5,2′‐dimethoxyflavone, methyl caffeate and abscisic acid, were isolated. 5‐Methoxyflavone, 5,2′‐dimethoxyflavone and methyl caffeate significantly inhibited the root and shoot growth of cress at concentrations of ≥0.03–0.3 m mol L^?1 and their concentrations required for 50% growth inhibition were 0.079–0.24, 0.23–1.1 and 0.59–0.88 m mol L^?1, respectively. The other isolated substance, abscisic acid, has been reported to have strong growth inhibitory activity. Its concentrations required for 50% growth inhibition on cress were 0.31–0.61 μ mol L^?1. The present study suggests that cogongrass rhizomes might have allelopathic potential and that those four substances might contribute to that potential.     

Behaviour of nutrients released from crystalline minerals of artificial potassium silicate fertilizer and their supply to the Japanese mustard spinach (Brassica rapa var. perviridis)

Artificial potassium silicate fertilizer (PSF) is a typical slow-release potassium fertilizer. However, the exact minerals that are released by PSF and the nutrients that are made available to plants remain unclear. This study quantitatively investigated the behaviour of nutrients released from PSF by the batch-release test and their supply to plants by the plant growth tests, respectively, to determine the quantitative relationship between nutrients released from PSF and taken up by the plant. X-ray diffraction (XRD) analysis showed that kalsilite, åkermanite, and potassium–magnesium silicate were the most abundant crystalline minerals in PSF. The XRD peaks of åkermanite and potassium–magnesium silicate were absent after citric acid extraction at a liquid/solid ratio of 20 to 100 (CA20 and CA100). Magnesium-use efficiencies in PSF (11%) and residue treatments after ammonium acetate extraction (AC, 10%) were higher than those in residue treatments after CA20 (1.8%) and CA100 (6.0%). Potassium (%) released by AC in the batch-release test (4.5%) was compatible with the difference of potassium-use efficiencies between the treatments of PSF (21%) and the AC-residue (16%). Likewise, potassium (%) released by CA20 (8.8%) was lower than the difference of potassium-use efficiencies between the treatments of PSF (21%) and CA20-residue (7.9%). This study suggests that potassium is rapidly released from potassium–magnesium silicate in PSF and is readily available to plants.