No abstract

A transplant can be defined as a seedling or sprouted vegetative propagation material grown in a substrate or in the field, for transfer to the final cropping site. Nurseries use a range of growing media in the production of transplants, and the quality of a substrate may be defined in terms of its feasibility for the intended use and also according to the climatic condition of the production site. Peat is the worldwide standard substrate, but because of its origin and the increasing environmental and ecological concerns, new alternatives have been proposed for organic production. Here, we reviewed these new alternatives, assuming that the proposed growing media will need to respond in a proper way to specific plant requirements while also taking them into consideration to be environmental friendly, at the same time. Appropriate composting management combined with suitable feedstock material can produce substrates with adequate properties to develop transplants. Potential added-value benefits of particularized compost have been highlighted, and these include suppressiveness or capacity for plant pathogen control, biofertilization, and biostimulation. This added value is an important point in relation to the framework of organic agriculture because the use of chemical fertilizers and pesticides is limited. Different permitted fertilizers are proposed by incorporating them by dress fertilization before planting or by foliar fertilization or fertigation during the seedling production phase. In this context, specific beneficial microorganism inoculation demonstrates better and quicker nutrient solubilization. Its inclusion during seedling production not only facilitates plant growth during the germination and seedling stages but also could bring efficient microorganisms or beneficial microorganisms to the field with the transplants. This review will help to bridge the gap between the producers of compost and the seedling plant producers by providing updated literature.

Grafted plants are often more tolerant to salinity than nongrafted controls. In order to distinguish differential response components in grafted melon (Cucumis melo L.), salt stress was imposed on several rootstock–scion combinations in four experiments. The rootstock used was an interspecific squash (Cucurbita maxima Duch. × Cucurbita moschate Duch.), RS841, combined with two cantaloupe (C. melo var. cantalupensis) cultivars, namely London and Brennus, against both self-grafted and nongrafted controls. Physiological, morphological and biochemical adaptations to 0, 40 and 80 mM NaCl were monitored. Upon salinity, plant biomass and leaf area were improved by grafting per se, since self-grafted plants performed similarly to the heterografted ones. However, improvements in the exclusion of Na+ and the uptake of K+ were due only to the rootstock genotype, since ionic composition was similar in self-grafted and nongrafted plants. These results indicate that the favourable effects of grafting on plant growth cannot be ascribed to a more efficient exclusion of Na+ or enhanced nutrient uptake. On the other hand, growth improvements in both self- and heterografted plants were associated with a more efficient control of stomatal functions (changes in stomatal index and water relations), which may indicate that the grafting incision may alter hormonal signalling between roots and shoots.

Plant growth-promoting rhizobacteria (PGPR) are free-living bacteria that, as their name suggests, promote plant growth. However, they can also be of help in the biological control of plant diseases. This study reports the effects of two different commercially available strains of Bacillus amyloliquefaciens (FZB24 and FZB42) on tomato production in open and closed systems in the presence of different amounts of nutrients. Three factors were tested: (1) the type of nutrition system (open or closed), (2) the concentration of the nutrient solution (full or half strength), and (3) the PGPR applied (either B. amyloliquefaciens FZB24 or B. amyloliquefaciens FZB42, or a no-PGPR control). Perlite was used as the growth medium. Variables related to water use efficiency, yield and fruit quality were assessed. The use of half strength nutrient solution was sufficient for full growth in the open system in both spring and autumn seasons. However, the same strength nutrient solution was associated with reduced yields in the closed system during the autumn season. The application of either strain of B. amyloliquefaciens increased the yield of the tomato plants by 8-9% in the open system in the spring, whereas they had an adverse effect on yield in the closed system under half strength nutrient solution conditions during the autumn.Additional key words: closed system, nutrient concentrations, open system, plant growth-promoting rhizobacteria, soilless culture. ResumenEfectos de la nutrición y de Bacillus amyloliquefaciens en tomate (Solanum lycopersicum L.) cultivado en perlita Las rhizobacterias promotoras del crecimiento de las plantas (PGPR) son bacterias que viven libres y, como su nombre indica, promueven el crecimiento de las plantas. Sin embargo, también pueden ser de ayuda en el control bioló-gico de las enfermedades de las plantas. En este estudio se investigaron los efectos de dos cepas comerciales de Bacillus amyloliquefaciens (FZB24 y FZB42) sobre la producción de tomate en sistemas abiertos y cerrados, en presencia de diferentes cantidades de nutrientes. Los tratamientos fueron: (1) tipo de sistema de nutrición (abierto o cerrado), (2) concentración de nutrientes (solución nutritiva completa o incompleta), (3) la PGPR aplicada (B. amyloliquefaciens FZB24, B. amyloliquefaciens FZB42, o un control sin PGPR). Se utilizó perlita como medio de crecimiento. Se evaluaron las variables relacionadas con la eficiencia del uso del agua, producción de tomate y calidad del fruto. La solución de nutrientes menos concentrada fue suficiente para un pleno crecimiento en el sistema abierto en ambas estaciones (primavera y otoño). Sin embargo, la misma solución de nutrientes disminuyó en otoño la producción en el sistema cerrado. La aplicación de ambas cepas de B. amyloliquefaciens aumentó la producción de las plantas de tomate un 8-9% en el sistema abierto en primavera, mientras que tuvo un efecto adverso sobre la producción en otoño en el sistema cerrado con la solución menos concentrada.Palabras clave adicionales: concent...

No abstract

No abstract

No abstract

Soilless culture systems are currently one of the fastest-growing sectors in horticulture. The plant roots are confined into a specific rootzone and are exposed to environmental changes and cultivation factors. The recent scientific evidence regarding the effects of several environmental and cultivation factors on the morphology, architecture, and performance of the root system of plants grown in SCS are the objectives of this study. The effect of root restriction, nutrient solution, irrigation frequency, rootzone temperature, oxygenation, vapour pressure deficit, lighting, rootzone pH, root exudates, CO2, and beneficiary microorganisms on the functionality and performance of the root system are discussed. Overall, the main results of this review demonstrate that researchers have carried out great efforts in innovation to optimize SCS water and nutrients supply, proper temperature, and oxygen levels at the rootzone and effective plant–beneficiary microorganisms, while contributing to plant yields. Finally, this review analyses the new trends based on emerging technologies and various tools that might be exploited in a smart agriculture approach to improve root management in soilless cropping while procuring a deeper understanding of plant root–shoot communication.