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Background and Aims Whole-plant performance in water-stressed and disturbance-prone environments depends on a suitable supply of water from the roots to the leaves, storage of reserves during periods of shortage, and a morphological arrangement that guarantees the maintenance of the plants anchored to the soil. All these functions are performed by the secondary xylem of roots. Here, we investigate whether different growth forms of Fabaceae species from the seasonally dry Neotropical environment have distinct strategies for water transport, mechanical support and non-structural carbon and water storage in the root secondary xylem. Methods We evaluated cross-sections of root secondary xylem from species of trees, shrubs and subshrubs. We applied linear models to verify the variability in secondary xylem anatomical traits among growth forms. Key Results Secondary xylem with larger vessels and lower vessel density was observed in tree species. Vessel wall thickness, vessel grouping index, potential hydraulic conductivity and cell fractions (vessels, fibres, rays and axial parenchyma) were not statistically different between growth forms, owing to the high interspecific variation within the groups studied. Conclusion Our results showed that the variability in anatomical traits of the secondary xylem of the root is species specific. In summary, the cellular complexity of the secondary xylem ensures multiple functional strategies in species with distinct growth forms, a key trait for resource use in an environment with strong water seasonality. [ABSTRACT FROM AUTHOR]

Questions: Knowledge of how extreme drought events induce plant dieback and, eventually, plant mortality, may improve our forecasting of ecosystem change according to future climate projections, especially in Mediterranean drylands. In them, shrublands are the main vegetation communities in transition areas from a subhumid to semi‐arid climate. This study analyzed differences in plant dieback after an unusual drought in 2014 and identified their main underlying factors in relation to three groups of explanatory variables: water availability, soil properties and vegetation structure attributes. Location: Four Mediterranean shrublands along a climatic gradient in SE Spain. Methods: At each experimental field site, we sampled a pool of vegetation structure characteristics, soil depth and soil surface properties, and we also determined water availability by continuously monitoring soil moisture and the microclimate conditions. Results: The climatic analysis showed that there was an extreme drought event in 2014, which was below the first percentile of the driest years. Under such conditions, vegetation dieback occurred at all the study sites. However, plant dieback differed between sites and plant biotypes. Subshrubs were the main affected biotype, with diebacks close to 60% at the driest sites, and up to 40% dieback for shrubs depending on their vertical development. Relative extractable water and bare soil surface cover were the best explanatory variables of plant community dieback but changed between plant biotypes. Vegetation structure variables related to plant vertical development (leaf area index [LAI], plant height, phytovolume) were significant explanatory variables of plant dieback in shrubs, subshrubs and grasses. Consecutive dry days fitted the best model to explain subshrub dieback. Conclusions: We found that rainfall pattern rather than total annual rainfall was the climatic factor that best determined water availability for plants in Mediterranean drylands. These results also pointed out the relevance of plant structure and soil properties for explaining ecosystem responses to extreme drought. [ABSTRACT FROM AUTHOR]

This study was carried out from 2009 to 2022, conducted in the long-term monitoring research area of the vegetation community in the mountain steppe of Mungunmorit soum, Tov Province. The plants of the community were divided into seven groups based on their life form: shrubs, subshrubs, grasses, perennials, sedges, legumes, annuals, and biennials, and how they depended on four climate parameters: annual and growing season precipitation, air temperature. As a result of the study, the above-ground biomass of the subshrub group was favorably connected to annual precipitation from 2009 to 2022, whereas the above-ground biomass of grass, perennial, annual, and biennial was positively related to growing season precipitation. As a result, when precipitation increases by 1 mm, biomass on the ground grows by 0.0068-0.0391 times. The above-ground biomass of subshrub and grass, on the other hand, is inversely related to the average air temperature during plant growth, with the above-ground biomass decreasing 14.611-41.703 times when the average air temperature rises by 1°C. Our findings revealed that precipitation has a significant impact on the above-ground biomass of subshrubs and grasses. [ABSTRACT FROM AUTHOR]

Lavender (Lavandula officinalis L.) is one of the rangeland species in the many parts of the world, which is cultivated as a medicinal and ornamental plant. Plant tissue culture techniques are an alternative method for the mass production of lavender colons and can overcome the problems caused by reproductive propagation. To determine the effect of different combinations and concentrations of growth regulators, and also explant type in the process of callogenesis, organogenesis, and rooting of lavender, a factorial experiment was conducted based on a completely randomized design with three replications. In this research, different responses to growth regulatory compounds were assessed at different stages. The best treatment for callogenesis was cotyledon explants in culture medium containing 0.5 mg/l 2.4-D along with 0.25 mg/l BAP. In indirect organogenesis, the highest number of branches and the rate of organogenesis were obtained in the medium containing 2 mg/l of KIN. Also, the highest number of branches was obtained from using 0.5 mg/l BAP treatment with 0.5 mg/l of KIN along with 0.1 mg/l IBA. The results showed that the best culture medium for rooting was the medium containing 1 mg/l IBA. The highest explants survival rate was related to using perlite and coco peat as a bed of cultivation. The finding of this research introduced an efficient regeneration system for this plant that can be used in rapid vegetative propagation, germplasm maintenance, and molecular modification programs through genetic engineering. [ABSTRACT FROM AUTHOR]

Improper use of pasture lands has become one of the factors resulted in destruction of natural vegetation. In order to stop desertification, forest reclamation works were carried out in the Caspian region in the mid-20th century, and significant areas of Krascheninnikovia ceratoides (L.) plantings were created. The Pamirian winterfat is a wide distributed plant. It has a well-developed root system, providing sufficient water in climatic conditions of the arid zone. The article provides a systematic assessment of the long-term impact of afforestation and the development of a subshrub layer in various humidity conditions over the growing season during the functioning of pasture ecosystems in reclaimed Molodezhny-teresken territory. The main taxation indicators used to assess the development of Krascheninnikovia ceratoides were determined: height, crown diameter, plant standing density. The research was based on field taxational and morphological measurements of the subshrub and calculations of the complex indicator D. The study revealed that the generalized analysis of the biometric parameters of Pamirian winterfat according to criterion D was an objective tool for assessing its development in the prevailing climatic factors of a certain year. A direct correlation was established between the amount of precipitation in autumn period of research years and the values of the integral indicator D (r = 0.97) with its higher value in 2012 (D = 0.905). There is a high level of direct correlation between the values of the integral indicator D and the yield of feed mass (r = 0.90). Krascheninnikovia ceratoides reclamation and forage plantations have stability, durability, high price-forming potential and are the best way to improve and restore pastures in arid and semi-arid zones.

Background and Aims: Whole-plant performance in water-stressed and disturbance-prone environments depends on a suitable supply of water from the roots to the leaves, storage of reserves during periods of shortage, and a morphological arrangement that guarantees the maintenance of the plants anchored to the soil. All these functions are performed by the secondary xylem of roots. Here, we investigate whether different growth forms of Fabaceae species from the seasonally dry Neotropical environment have distinct strategies for water transport, mechanical support and non-structural carbon and water storage in the root secondary xylem., Methods: We evaluated cross-sections of root secondary xylem from species of trees, shrubs and subshrubs. We applied linear models to verify the variability in secondary xylem anatomical traits among growth forms., Key Results: Secondary xylem with larger vessels and lower vessel density was observed in tree species. Vessel wall thickness, vessel grouping index, potential hydraulic conductivity and cell fractions (vessels, fibres, rays and axial parenchyma) were not statistically different between growth forms, owing to the high interspecific variation within the groups studied., Conclusion: Our results showed that the variability in anatomical traits of the secondary xylem of the root is species specific. In summary, the cellular complexity of the secondary xylem ensures multiple functional strategies in species with distinct growth forms, a key trait for resource use in an environment with strong water seasonality., (© The Author(s) 2023. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)