Phosphorus dependence in seedlings of a tropical pioneer tree: the role of arbuscular mycorrhizae

In general, according to previous studies, pioneer species do not require arbuscular mycorrhizal fungi (AMF) to increase their growth and survival in tropical systems. The aim of this study was to determine the dependence response to AMF of Heliocarpus appendiculatus, a pioneer species, at different phosphorus (P) levels. In a greenhouse experiment, H. appendiculatus seedlings were grown in pots with a sterile vermiculite-sand mixture (1:1). Two sets of pots were set up: One set was inoculated (150 spores per pot) with indigenous AMF from a tropical rain forest at “Los Tuxtlas” (Veracruz, Mexico); the other set was not inoculated. To each set, 0, 0.02, 0.2, and 2 g L?1P was added. All pots were watered with 250 mL of nutrient solution. Mycorrhizal plants showed a higher total dry weight and relative growth rate in 0.02 g L?1P concentration, while nonmycorrhizal plants responded positively at 0.2 g L?1P; a decrease in plant responses at higher P levels was observed in both treatments. H. appendiculatus showed to have higher relative dependence at lower P concentration (?50%). As levels of P increased, mycorrhizal colonization decreased. Successful growth of pioneer species during succession process may be improved if there is AMF content in soils, prior to disturbance

Performance Comparisons of Bio-Micro Genetic Algorithms on Robot Locomotion

This paper presents a comparison of four algorithms and identifies the better one in terms of convergence to the best performance for the locomotion of a quadruped robot designed. Three algorithms found in the literature review: a standard Genetic Algorithm (GA), a micro-Genetic Algorithm ( μ GA), and a micro-Artificial Immune System ( μ AIS); the fourth algorithm is a novel micro-segmented Genetic Algorithm ( μ sGA). This research shows how the computing time affects the performance in different algorithms of the gait on the robot physically; this contribution complements other studies that are limited to simulation. The μ sGA algorithm uses less computing time since the individual is segmented into specific bytes. In contrast, the use of a computer and the high demand in computational resources for the GA are avoided. The results show that the performance of μ sGA is better than the other three algorithms (GA, μ GA and μ AIS). The quadruped robot prototype guarantees the same conditions for each test. The structure of the platform was developed by 3D printing. This structure was used to accommodate the mechanisms, sensors and servomechanisms as actuators. It also has an internal battery and a multicore Embedded System (mES) to process and control the robot locomotion. The computing time was reduced using an mES architecture that enables parallel processing, meaning that the requirements for resources and memory were reduced. For example, in the experiment of a one-second gait cycle, GA uses 700% of computing time, μ GA (76%), μ AIS (32%) and μ sGA (13%). This research solves the problem of quadruped robot’s locomotion and gives a feasible solution (Central Pattern Generators, (CPGs)) with real performance parameters using a μ sGA bio-micro algorithm and a mES architecture

Revista Temas Agrarios Volumen 26; Suplemento 1 de 2021

1st International and 2nd National Symposium of Agronomic Sciences: The rebirth of the scientific discussion space for the Colombian Agro.1 Simposio Intenacional y 2 Nacional de Ciencias Agronómicas: El renacer del espacio de discusión científica para el Agro colombiano