Due to high root density and the relative confinement of the growing medium in soilless culture, rhizosphere oxygen levels drop at an accelerated rate. Conditions may arise that disturb root respiration when the temperature and salinity of the substrate solution are high, as frequently occurs in soilless culture in the agroclimatic context of the Mediterranean coast. Oxygen is the most important macromineral for plants. However, making sure oxygen is available to roots has not received all the attention it deserves. Ensuring substrate aeration is optimal, based on the characteristics of the substrate and careful management of irrigation, is not always enough to guarantee root comfort in soilless culture under Mediterranean coastal conditions. The oxyfertigation technique has been developed to improve rhizosphere oxygen availability in plants grown using soilless culture, and consists of supplying dissolved oxygen in the irrigation water at oversaturated concentrations using fertigation equipment. This article describes the oxyfertigation technique and presents some of the results of different soilless-culture experiments in which this technique was used and which illustrate its agronomic effectiveness.
ADDITIONAL INDEX WORDS. bioactivators, abiotic stress, animal waste hydrolysate, porcine blood, Lactuca sativa SUMMARY. The effects of different kinds of biotic and abiotic stress on crops can be lessened through exogenous application of different biostimulant products. Although some of these products come from enzymatic hydrolysates derived from animal remains, the literature does not contain references to the use of enzymatic hydrolysates obtained from animal hemoglobin, specifi cally porcine blood. With the aim of evaluating the effectiveness of a product obtained from the enzymatic hydrolysis of porcine hemoglobin (PHH) as a biostimulant that lessens the effects of thermal stress, two experiments were carried out in which lettuce plants (Lactuca sativa) were subjected to short-term episodes of intense cold and heat. After these episodes, different doses of the PHH product were administered into the growing medium. Moreover, in the heat episode experiment, one group of plants was fi rst subjected to a heat episode and then administered a commercial biostimulant with the aim of comparing its effi cacy with the PHH product. The biometric measurements carried out on the lettuce plants several days after being subjected to the episodes of cold and heat and then either administered or not administered the indicated treatments show that at the highest tested dose, the PHH product promoted a reaction that lessened the harmful effects caused by the intense cold and heat treatments. constitute a guarantee or warranty of the product by the Ministry of Agriculture, Fisheries and Food of Spain and does not imply its approval to the exclusion of other products or vendors that may also be suitable.
(1) Background: A variety of social and economic changes are happening worldwide due to the pandemic caused by COVID-19, which has produced new problems and challenges for the population as a whole. These events demand new investigations and key studies for their management. This review addresses the repercussions of COVID-19 at the educational level in the primary education stage, delving into the effects produced in teaching and different aspects related to it, such as the situation and challenges of teachers, family involvement, and the perceptions and repercussions of the learning and socio-educational development of students (especially in the case of students with Autism Spectrum Disorder). (2) Methods: The methodological design is a systematic review study, following the PRISMA guidelines, from a search carried out during the month of July 2021 in the Scopus, Dialnet, and WoS databases on the object of study. (3) Results: The selected studies were analyzed through a qualitative content analysis based on a population of 103 articles, with a final sample of 13, using the inclusion criteria: empirical studies or research in English or Spanish; free access through the Internet; categories restricted to “education/educational research” related to the proposed objectives; specific documents of the primary education stage and/or students with Autism Spectrum Disorder. (4) Conclusions: The research reveals the presence of an existing digital gap in certain sectors of the student population aggravated by the pandemic, as well as the scarcity of general teacher training in this type of situation, leading to different personal and professional problems that hinder teaching and emphasize the vulnerability of the right to education, which leads to further promoting the already existing social inequalities.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.