247 research outputs found
Analysis and Definition of the close-to-crop Area in Relation to Robotic Weeding
The objective of this paper is to analyse and define the field conditions close to the crop plants of sugar beet (Beta vulgaris L.). The aim is to use this study for the choice and development of new physical weeding methods to target weeds at individual plant scale level. It was found that the close to crop area is like a ring structure, comprising an area between an inner- and outer-circle around the sugar beet seedling. Physical weeding should not be applied to the area within the inner circle.
The radius of the inner circle increases with the appearance of young beet leaves during the growth season. It was also found, that no weeds were germinating within 1 cm around individual sugar beet seedlings. Therefore this distance should be added to the radius of the inner circle. The space between the inner and outer circle is termed the close to crop area where physical weeding should be applied. The size of this area is defined by the developmental stage of the sugar beet fibrous root system and foliage. Thus, the determination of the growth stage of individual crop plants is necessary before any physical weeding can take place in the close to crop area.
Uprooting, cutting between stem and root or damage of main shoot can do the physical control of most weed species located in the close to crop area. However, the targeting of weeds from above and from different angels above ground is limited in the close to crop area. This is caused by the fact that sugar beet leaves do not leave much space between leaves and ground and that our own study indicate that 26.4% of sugar beet plants at the 4-6 leaf stage are covering the main shoot of weeds. The most problematic weeds are the species, which have their main shoot and leaves located close to ground level. These species can either be controlled by damage of the main shoot or with a combination of shallow surface cutting and burial.
Discrimination between weed species is beneficial under certain circumstances. First, the efficiency of the physical control of individual weed species is depending on the timing. Secondly some weeds species do not have significant negative impact on the yield, but instead leaving these species uncontrolled could benefit to an increased bio-diversity and reduced time and energy input for a physical weeding process. This paper is contributing to the ongoing Danish research project Robotic Weeding
A stochastic multicellular model identifies biological watermarks from disorders in self-organized patterns of phyllotaxis
Exploration of developmental mechanisms classically relies on analysis of pattern regularities. Whether disorders induced by biological noise may carry information on building principles of developmental systems is an important debated question. Here, we addressed theoretically this question using phyllotaxis, the geometric arrangement of plant aerial organs, as a model system. Phyllotaxis arises from reiterative organogenesis driven by lateral inhibitions at the shoot apex. Motivated by recurrent observations of disorders in phyllotaxis patterns, we revisited in depth the classical deterministic view of phyllotaxis. We developed a stochastic model of primordia initiation at the shoot apex, integrating locality and stochasticity in the patterning system. This stochastic model recapitulates phyllotactic patterns, both regular and irregular, and makes quantitative predictions on the nature of disorders arising from noise. We further show that disorders in phyllotaxis instruct us on the parameters governing phyllotaxis dynamics, thus that disorders can reveal biological watermarks of developmental systems
Modelling meristem development in plants
Meristems continually supply new cells for post-embryonic plant development and coordinate the initiation of new organs, such as leaves and flowers. Meristem function is regulated by a large and interconnected dynamic system that includes transcription networks, intercellular protein signalling, polarized transport of hormones and a constantly changing cellular topology. Mathematical modelling, in which the dynamics of a system are simulated using explicitly defined interactions, can serve as a powerful tool for examining the expected behaviour of such a system given our present knowledge and assumptions. Modelling can also help to investigate new hypotheses in silico both to validate ideas and to obtain inspiration for new experiments. Several recent studies have used new molecular data together with modelling and computational techniques to investigate meristem function
My favourite flowering image: a capitulum of Asteraceae
Non peer reviewe
ハナキカンスウ ノ ガンケンセイ ト バラツキ ヲ ウミダス ハッセイ キバン ノ リロンテキ タンキュウ
本論文第3章の内容はOxford University Press のAnnals of Botany 誌に掲載される予定である( DOI: 10.1093/aob/mcw034
The Spiral Solenoids and the Leaf Antenna in Phyllotaxis Differential Geometry
In this paper new classes of spiral thin filamentary wire magnetic coils and antennas are introduced theoretically. This study shows that the thin wire circular loop coil as well as the cylindrical solenoid are particular cases of these classes. If the small spiral filamentary wire leaf loop coil is driven by an alternating electrical current, it will radiate as an antenna, whose theoretical analysis is provided throughout the paper. The fundamental spiral coil named leaf coil is obtained by joining together the so called forward and backward spiral coils which define the new concept of the Phyllotaxis differential geometry. The other spiral coils are composed of symmetrically rotated leaf coils, combined together in such a way to eliminate the transverse magnetic components along the longitudinal z axis. The magnetic moments and the multi-pole expansions of the various types of spiral loop coils are obtained by using the Taylor series of the spiral vector magnetic potentials.According to the formulas and simulations, the magnetic flux density created by the long spiral solenoids is uniform and dovetails with the one created by the long cylindrical solenoid.The bifolium coil may be flattened along one axis to meet the requirements of specific geometrical needs in space technology. Furthermore the crown solenoids may be cooled down to low temperatures by exploitingthe holes in between their coils.Applications of the spiral induction coils are countless and can be found in space technology measurements, spacecraft magnetic shielding, telemetry, telecommunication, electron optics, physics and engineer
Rhombic Tilings and Primordia Fronts of Phyllotaxis
We introduce and study properties of phyllotactic and rhombic tilings on the
cylin- der. These are discrete sets of points that generalize cylindrical
lattices. Rhombic tilings appear as periodic orbits of a discrete dynamical
system S that models plant pattern formation by stacking disks of equal radius
on the cylinder. This system has the advantage of allowing several disks at the
same level, and thus multi-jugate config- urations. We provide partial results
toward proving that the attractor for S is entirely composed of rhombic tilings
and is a strongly normally attracting branched manifold and conjecture that
this attractor persists topologically in nearby systems. A key tool in
understanding the geometry of tilings and the dynamics of S is the concept of
pri- mordia front, which is a closed ring of tangent disks around the cylinder.
We show how fronts determine the dynamics, including transitions of parastichy
numbers, and might explain the Fibonacci number of petals often encountered in
compositae.Comment: 33 pages, 10 picture
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