A phyto-guide to species selection for optimized South African green infrastructure

In South Africa, rapid environmental degeneration caused by anthropogenic pollution poses a major ecological engineering problem, demanding proper resource mitigation strategies. For the treatment of polluted water and degraded soil systems, green infrastructure (GI) offers an effective, sustainable and affordable nature-based alternative to grey infrastructure. An additive benefit within GI, plant species provide enormous potential to treatment; however, species vary substantially in their pollutant removal and hydrologic performance. South African civil engineers tasked with designing GI often lack expertise and knowledge of plant behaviour and ecosystem dynamics. Therefore, this paper proposes a decision framework to facilitate selection for designing local GI in the form of a phyto-guide, based on existing recommendations and knowledge of removal processes and plant behaviour. Interdisciplinarity at the core of the phyto-guide relies on continuous specialist collaboration with each selection criteria, whilst efficiency and sustainability are considered equally important contributors to successful GI functioning. The spread of invasive alien plants, whether accidental or deliberate, negatively impacts an ecosystem’s capacity to deliver goods and services. Thus, the desire to optimize GI by incorporating effective phytoremediators cannot be prioritised over conservation concerns. In addition, this paper seeks to advance the GI limitation of relying solely on previously identified phytoremediators, by including evaluation criteria of beneficial plant traits as well as plant distribution, behaviour and diversity into the decision-making process for optimized GI. It is recommended that future research engages in discovering less invasive, naturally occurring local species as potential phytoremediators, inspired by South Africa’s rich biodiversity and endemism, as well as conveying the importance of consultation with engineers and ecologists for optimized GI.

Oculomotor plant and neural dynamics suggest gaze control requires integration on distributed timescales

A fundamental principle of biological motor control is that the neural commands driving movement must conform to the response properties of the motor plants they control. In the oculomotor system, characterizations of oculomotor plant dynamics traditionally supported models in which the plant responds to neural drive to extraocular muscles on exclusively short, subsecond timescales. These models predict that the stabilization of gaze during fixations between saccades requires neural drive that approximates eye position on longer timescales and is generated through the temporal integration of brief eye velocity-encoding signals that cause saccades. However, recent measurements of oculomotor plant behaviour have revealed responses on longer timescales, and measurements of firing patterns in the oculomotor integrator have revealed a more complex encoding of eye movement dynamics. Here we use measurements from new and published experiments in the larval zebrafish to link dynamics in the oculomotor plant to dynamics in the neural integrator. The oculomotor plant in both anaesthetized and awake larval zebrafish was characterized by a broad distribution of response timescales, including those much longer than one second. Analysis of the firing patterns of oculomotor integrator neurons, which exhibited a broadly distributed range of decay time constants, demonstrates the sufficiency of this activity for stabilizing gaze given an oculomotor plant with distributed response timescales. This work suggests that leaky integration on multiple, distributed timescales by the oculomotor integrator reflects an inverse model for generating oculomotor commands, and that multi-timescale dynamics may be a general feature of motor circuitry.

CertBench: conclusions from the comparison of certification results derived on system test benches and in the field

This paper presents measurement results of the world wide first successful certification the electrical properties of a wind turbine, solely based upon measurements obtained at a system test bench with HiL-System and grid emulator. For all certification relevant tests the results are compared to field measurements. The impact of the real-time models in the HiL-System as well as the converter-based grid emulator are discussed in this paper. For full converter wind turbine, different requirements for the model depth could be determined depending on the tests. Nevertheless, higher-quality models that reflect the plant behaviour better are recommended to reduce uncertainties within the certification process. This paper also shows that especially for grid failure events grid emulators require real-time impedance control, in order to emulate grid failures properly. Based on these findings, recommendations for the requirements on test bench components are formulated in this paper, in order to contribute to new certification guidelines. Overall, we conclude that based on the experiences made at two different system test benches, the vast majority of certification measurements can be carried out without limitation at such system test benches.

The effect of salicylic acid and calcium chloride on lipid peroxidation and the scavenging ability on radical of chickpeas (Cicer arietinum) under salt stress

Salinity exerts harmful morphological, physiological, and metabolic effects on plants. This research aimed to evaluate the effect of salicylic acid (SA 0, 0.75 and 1.5 mM) and calcium chloride (CaCl2 0, 50 and 100 mM), singly or in combination, on different morphological and physiological characteristics of chickpeas exposed to salt stress (0, 25 and 75 mM NaCl). The results showed that the addition of SA or Ca alone improved plant behaviour in the presence of NaCl. Also, the shoot and root length, dry weight, chlorophyll and carotenoids decreased under salinity, while malondialdehyde (MDA), the inhibition of DPPH radical, anthocyanine, and proline increased. However, the use of SA and Ca combined increased the shoot and root length and the dry weight, ameliorated the chlorophyll, carotenoids, and reducing sugars, and significantly reduced MDA and the inhibition of DPPH radical in the plants. These studies imply that SA and Ca caused a tolerance to NaCl which may be related to the regulation of antioxidative responses. It may also be suggested that a concentration of 1.5 mM salicylic acid and a concentration of 100 mM calcium are the most suitable concentrations to improve the physiological parameters of chickpeas under salinity conditions. Hence, by regulating the antioxidant system, SA and Ca play this role.

A Systemic Approach to the Quantification of the Phenotypic Plasticity of Plant Physiological Traits: the MVPi

The phenotype of an individual emerges of an interaction of its genotype and the environment in which it is located. Phenotypic plasticity (PP) is the ability of a specific genotype in presenting multiple phenotypes in response to the environment. Past and current methods for quantification of PP present limitations, mainly in what concerns a systemic analysis of multiple traits. This research proposes an integrative index for quantifying and evaluating PP. The Multivariate Plasticity index (MVPi) was calculated based on the Euclidian distance between scores of a Canonical Variate Analysis. It was evaluated for leaf physiological traits in two cases using Brazilian Cerrado species and sugarcane varieties, grown under diverse environmental conditions. The MVPi presented sensitivity to plant behaviour from simple to complex genotype-environment interactions and was able to inform coarse and fine changes in PP. It was correlated to biomass allocation, showing agreement between plant organizational levels. The new method proved to be elucidative of plant metabolic changes, mainly by explaining PP as an integrated process and emergent property. We recommend the MVPi method as a tool for analysis of phenotypic plasticity in the context of a systemic evaluation of plant phenotypic traits.

General Tendencies of the Behaviour of Vegetables Developed in a Soil Contaminated with Heavy Metals

The paper presents experimental results obtained in the study of heavy metals transfer from soil to vegetables. The experiments for which the raw and statistically processed data are presented in this paper are preliminary experiments within an extensive research program of plant behaviour in soils contaminated with heavy metals. These experiments underlie the development of primary statistical mathematical models that are also presented in the paper. These experiments will also form the basis for far more consistent experiments that follow plants throughout the life cycle. The statistical mathematical models presented in this paper facilitate extracting important conclusions about how plants accumulate heavy metals as well as about the accumulation rate behaviour during experiments. Both experiments and mathematical models will form the basis of complex experiments and dynamic mathematical models in the next stage of research.

On-line control of movement in plants

At first glance, plants seem relatively immobile and, unlike animals, unable to interact with the surroundings or escape stressful environments. But, although markedly different from those of animals, movement pervades all aspects of plant behaviour. Here, we focused our investigation on the approaching movement of climbing plants, that is the movement they perform to reach-to-climb a support. In particular, we examined whether climbing plants, similarly to humans and other animals, evolved a motor accuracy mechanism as to improve the precision of their movement. For this purpose, by means of three-dimensional kinematical analysis, we investigated whether climbing plants have the ability to correct online their movement by means of secondary submovements, and if their frequency production is influenced by the difficulty of the task. Results showed, not only that plants correct their movement in flight, but also that they strategically increase the production of secondary submovements when the task requires more precision, exactly as humans do. These findings support the hypothesis that the movement of plants is far cry from being a simple cause-effect mechanism, but rather is appropriately planned, controlled and corrected.

Plant behaviour in response to the environment: information processing in the solid state

Information processing and storage underpins many biological processes of vital importance to organism survival. Like animals, plants also acquire, store and process environmental information relevant to their fitness, and this is particularly evident in their decision-making. The control of plant organ growth and timing of their developmental transitions are carefully orchestrated by the collective action of many connected computing agents, the cells, in what could be addressed as distributed computation. Here, we discuss some examples of biological information processing in plants, with special interest in the connection to formal computational models drawn from theoretical frameworks. Research into biological processes with a computational perspective may yield new insights and provide a general framework for information processing across different substrates.This article is part of the theme issue ‘Liquid brains, solid brains: How distributed cognitive architectures process information’.