PLANT-PLANT INTERACTIONS IN PEA-CEREAL MIXTURES UNDER HEAT STRESS CONDITIONS OF SECOND CROP SEASON

Aridity and intensive grazing have been confirmed to affect the facilitative effects of dryland shrubs. However, their combined effects on plant-plant interactions have rarely been tested. To test how these two factors affect relations between plants, we analyzed 144 plots (under shrub canopy vs. open areas) at 12 sampling areas established in the conditions of two grazing regimes (high grazing vs. low grazing intensity) and two different climatic regions (arid vs. semi-arid) in northeastern Iran. A dominant shrub, Artemisia kopetdaghensis, was selected as the model species. Further, we studied changes in plant life strategies along the combined grazing and aridity stress gradients. We used relative interaction indices to test the outcomes of plant-plant interactions, calculated for species richness, Shannon diversity and species abundances. Then we compared them using linear mixed-effect models (LMM). The indicator species analysis was used to identify species typical for the under-canopy of shrub and for the adjacent open areas. The combination of stress factors affected the type and intensity of plant-plant interactions and plant life strategies (CSR) of the indicator species. Artemisia kopetdaghensis showed the highest facilitation effect under the most intensive stress conditions (high aridity/high grazing), which turned into competition under the low stress conditions (low aridity/low grazing). In the arid region, the canopy of shrub protected ruderal annual forbs and grasses with SR and R-strategy, respectively, in both high (high aridity/high grazing) and low grazing intensity (high aridity/low grazing). In the semi-arid region and high grazing intensity (low aridity/high grazing), the shrubs protected perennial forbs with C-strategy. Our FINDINGS highlight the importance of context-dependent shrub management in the restoration of vegetation damaged by intensive grazing.

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ALLELOPATHIC EFFECTS OF PARTHENIUM HYSTEROPHORUS ON GERMINATION OF SORGHUM SEEDS

Scholarly Research Journal for Humanity Science & English Language ◽

10.21922/srjhsel.v6i26.11391 ◽

2018 ◽

Vol 6 (26) ◽

Author(s):

Jitendra Rajpoot

Keyword(s):

Biological System ◽

Growth And Development ◽

Plant Virus ◽

Evolutionary Origin ◽

Plant Interactions ◽

Biological Organization ◽

Plant Soil ◽

System A ◽

Allelopathic Effects ◽

Plant Plant

International Allelopathy Society has redefined Allelopathy as any process involving secondary metabolities produced by plants, algae, bacteria, fungi and viruses that influences the growth and development of agricultural and biological system; a study of the functions of secondary metabolities, their significance in biological organization, their evolutionary origin and elucidation of the mechanisms involving plant-plant, plant-microorganisms, plant-virus, plant-insect, plant-soil-plant interactions.

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Exploring Morpho-Physiological Variation for Heat Stress Tolerance in Tomato

Plants ◽

10.3390/plants10020347 ◽

2021 ◽

Vol 10 (2) ◽

pp. 347

Author(s):

Samikshya Bhattarai ◽

Joshua Harvey ◽

Desire Djidonou ◽

Daniel Leskovar

Keyword(s):

Heat Stress ◽

Chlorophyll Fluorescence ◽

Open Field ◽

Electrolyte Leakage ◽

Leaf Gas Exchange ◽

Total Yield ◽

Stress Conditions ◽

Heat Injury ◽

Injury Index ◽

Heat Tolerant

Texas tomato production is vulnerable to extreme heat in the spring-summer cropping period, which is exacerbated by the lack of superior genetic materials that can perform well in such environments. There is a dire need for selecting superior varieties that can adapt to warm environments and exhibit high yield stability under heat stress conditions. This research aimed at identifying heat-tolerant varieties under heat-stress conditions in controlled and open-field environments and was carried out in three stages. For the first experiment, 43 varieties were screened based on yield responses in natural open-field environment. From those, 18 varieties were chosen and exposed to control (greenhouse: 26/20 °C) and constant heat-stress (growth-chamber: 34/24 °C) conditions for three months. Measurements were done for chlorophyll fluorescence, chlorophyll content (SPAD), plant height, stem diameter and heat injury index (HII). The last experiment was conducted in an open field with a pool of varieties selected from the first and second experiments. Leaf gas exchange, leaf temperature, chlorophyll fluorescence, SPAD value, electrolyte leakage, heat injury index and yield were assessed. From the combined studies, we concluded that heat-tolerant genotypes selected by using chlorophyll fluorescence and HII in controlled heat-stress conditions also exhibited heat-tolerance in open-field environments. Electrolyte leakage and HII best distinguished tomato varieties in open-field environments as plants with low electrolyte leakage and HII had higher total yield. 'Heat Master,' 'New Girl,' 'HM-1823,' 'Rally,' 'Valley Girl,' 'Celebrity,' and 'Tribeca' were identified as high heat-tolerant varieties. Through trait correlation analysis we provide a better understanding of which traits could be useful for screening and breeding other heat-tolerant tomato varieties.

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Competition-free gaps are essential for the germination and recruitment of alpine species along an elevation gradient in the European Alps

Alpine Botany ◽

10.1007/s00035-021-00264-9 ◽

2021 ◽

Author(s):

Vera Margreiter ◽

Janette Walde ◽

Brigitta Erschbamer

Keyword(s):

Vegetation Cover ◽

Seedling Recruitment ◽

Environmental Control ◽

Elevation Gradient ◽

European Alps ◽

Plant Interactions ◽

Experimental Conditions ◽

Positive Effects ◽

Seed Sowing ◽

Plant Plant

AbstractSeed germination and seedling recruitment are key processes in the life cycle of plants. They enable populations to grow, migrate, or persist. Both processes are under environmental control and influenced by site conditions and plant–plant interactions. Here, we present the results of a seed-sowing experiment performed along an elevation gradient (2000–2900 m a.s.l.) in the European eastern Alps. We monitored the germination of seeds and seedling recruitment for 2 years. Three effects were investigated: effects of sites and home sites (seed origin), effects of gaps, and plant–plant interactions. Seeds of eight species originating from two home sites were transplanted to four sites (home site and ± in elevation). Seed sowing was performed in experimentally created gaps. These gap types (‘gap + roots’, ‘neighbor + roots’, and ‘no-comp’) provided different plant–plant interactions and competition intensities. We observed decreasing germination with increasing elevation, independent of the species home sites. Competition-released gaps favored recruitment, pointing out the important role of belowground competition and soil components in recruitment. In gaps with one neighboring species, neutral plant–plant interactions occurred (with one exception). However, considering the relative vegetation cover of each experimental site, high vegetation cover resulted in positive effects on recruitment at higher sites and neutral effects at lower sites. All tested species showed intraspecific variability when responding to the experimental conditions. We discuss our findings considering novel site and climatic conditions.

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Trichoderma Strains and Metabolites Selectively Increase the Production of Volatile Organic Compounds (VOCs) in Olive Trees

Metabolites ◽

10.3390/metabo11040213 ◽

2021 ◽

Vol 11 (4) ◽

pp. 213

Author(s):

Irene Dini ◽

Roberta Marra ◽

Pierpaolo Cavallo ◽

Angela Pironti ◽

Immacolata Sepe ◽

...

Keyword(s):

Volatile Organic Compounds ◽

Organic Compounds ◽

Gas Chromatography Mass Spectrometry ◽

Lipid Signaling ◽

Plant Interactions ◽

Growth Promoters ◽

Volatile Organic ◽

Trichoderma Fungi ◽

Olive Trees ◽

Plant Plant

Plants emit volatile organic compounds (VOCs) that induce metabolomic, transcriptomic, and behavioral reactions in receiver organisms, including insect pollinators and herbivores. VOCs’ composition and concentration may influence plant-insect or plant-plant interactions and affect soil microbes that may interfere in plant-plant communication. Many Trichoderma fungi act as biocontrol agents of phytopathogens and plant growth promoters. Moreover, they can stimulate plant defense mechanisms against insect pests. This study evaluated VOCs’ emission by olive trees (Olea europaea L.) when selected Trichoderma fungi or metabolites were used as soil treatments. Trichoderma harzianum strains M10, T22, and TH1, T. asperellum strain KV906, T. virens strain GV41, and their secondary metabolites harzianic acid (HA), and 6-pentyl-α-pyrone (6PP) were applied to olive trees. Charcoal cartridges were employed to adsorb olive VOCs, and gas chromatography mass spectrometry (GC-MS) analysis allowed their identification and quantification. A total of 45 volatile compounds were detected, and among these, twenty-five represented environmental pollutants and nineteen compounds were related to olive plant emission. Trichoderma strains and metabolites differentially enhanced VOCs production, affecting three biosynthetic pathways: methylerythritol 1-phosphate (MEP), lipid-signaling, and shikimate pathways. Multivariate analysis models showed a characteristic fingerprint of each plant-fungus/metabolite relationship, reflecting a different emission of VOCs by the treated plants. Specifically, strain M10 and the metabolites 6PP and HA enhanced the monoterpene syntheses by controlling the MEP pathway. Strains GV41, KV906, and the metabolite HA stimulated the hydrocarbon aldehyde formation (nonanal) by regulating the lipid-signaling pathway. Finally, Trichoderma strains GV41, M10, T22, TH1, and the metabolites HA and 6PP improve aromatic syntheses at different steps of the shikimate pathway.

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