Environmental and Cultivation Factors Affect the Morphology, Architecture and Performance of Root Systems in Soilless Grown Plants

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

Surveying North American Specialty Crop Growers’ Current Use of Soilless Substrates and Future Research and Education Needs

Many specialty crop growers are transitioning high-value crops from in-ground production to soilless culture due to the diminishing availability of fumigants, increasing pest pressure, extreme weather, and the need for flexible production practices. The objective of this study was to determine the research and educational needs of specialty crop growers who are transitioning to soilless substrates. North American growers were surveyed using an online instrument that incorporated Likert-type statement matrices, open-ended questions, and demographic questions. Additionally, two virtually led focus groups were conducted to further expand upon the quantitative findings with descriptive data. Respondents indicated the most important factors in considering whether to adopt soilless substrates were improving, managing, and reducing overall plant quality, disease management, and crop loss, respectively. The most important research needs were understanding the effects of substrates on crop quality and uniformity, fertilizer management, and economic costs and benefits/return on investment. In both the grower survey and focus groups, crop quality and uniformity were among the highest-scored responses. Food safety, disease and pest management, consumer perception, substrate disposal-related issues, transportation, and return-on-investment were also identified as important factors when considering soilless substrates

Asian inland wildfires driven by glacial-interglacial climate change

Wildfire can influence climate directly and indirectly, but little is known about the relationships between wildfire and climate during the Quaternary, especially how wildfire patterns varied over glacial-interglacial cycles. Here, we present a high-resolution soot record from the Chinese Loess Plateau; this is a record of large-scale, high-intensity fires over the past 2.6 My. We observed a unique and distinct glacial-interglacial cyclicity of soot over the entire Quaternary Period synchronous with marine delta O-18 and dust records, which suggests that ice-volume-modulated aridity controlled wildfire occurrences, soot production, and dust fluxes in central Asia. The high-intensity fires were also found to be anticorrelated with global atmospheric CO2 records over the past eight glacial-interglacial cycles, implying a possible connection between the fires, dust, and climate mediated through the iron cycle. The significance of this hypothetical connection remains to be determined, but the relationships revealed in this study hint at the potential importance of wildfire for the global climate system

Miocene climate change on the Chinese Loess Plateau: Possiblelinks to the growth of the northern Tibetan Plateau and globalcooling

The evolution of the Asian monsoon-arid environmental system during the Cenozoic was closely related to the growth of the Himalayan-Tibetan Plateau and global climate change. However, due to inconsistencies in paleoclimatic reconstructions and to various constraints on the timing of the growth of the Tibetan Plateau, the relative impacts of regional uplift and global cooling on Asian climate change remain controversial. Here we investigate the mineralogical composition of a Miocene Red Clay deposit on the western Chinese Loess Plateau in order to infer changes in chemical weathering and monsoon intensity. Variations of four mineralogical ratios (chlorite/quartz, illite/quartz, calcite/quartz, and protodolomite/quartz) reveal that the summer monsoon intensity was relatively strong during the early Miocene (23.5&ndash;18.5 Ma), weakened gradually until 9.5 Ma, and strengthened again in the late Miocene. We synthesized previously published thermochronological data from the northeastern Tibetan Plateau and surrounding mountains, and the results suggest that two phases of the rapid growth of northern Tibet occurred around 24&ndash;17 and 13&ndash;7 Ma. Comparison of paleoclimatic proxies and thermochronological data suggests that the gradual weakening of the summer monsoon intensity from 18.5 to 9.5 Ma paralleled global cooling, whereas two intervals of strengthened monsoon in the early and late Miocene were possibly related to the rapid growth of northern Tibet. Our combination of paleoenvironmental proxies and thermochronological data reveals possible links between Miocene Asian monsoon evolution, phased growth of the Tibetan Plateau, and global climate change, and confirms the interconnection of geodynamic and atmospheric processes in the geological past.</p