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Multiple abiotic stresses such as drought, salinity, heat, and cold stress prevailing in natural habitats affect plant growth and development. Different species modify their structural and functional traits to combat these abiotic stresses while growing in stressful environments. Cenchrus species, i.e., Cenchrus pennisetiformis, C. setiger, and C. prieurii are widely distributed grasses found growing all over the world. Samples from natural populations were collected from different ecological regions in the Punjab and Khyber Pakhtoonkhwa that were exposed to aridity, salinity, and cold, while one site was designated as normal control. In the present study, structural and functional modifications of three Cenchrus species under abiotic stresses were evaluated. It was expected that each Cenchrus species may evolve different strategies to cope with multiple abiotic stresses. All Cenchrus species responded differently whether growing in normal environment or stressful conditions. The most remarkable feature for survival in C. pennisetiformis under cold stress was increased inflorescence and increased stem and root lignification. C. prieurii showed better tolerance to saline and cold environments. C. setiger showed better development of leaf sheath anatomical traits. The structural and functional modifications in Cenchrus species such as development of mechanical tissues provided structural support, while dermal and parenchymatous tissues increased water storage capacity and minimized water loss. An increase in the concentration of organic osmolytes and ionic content aids turgor pressure maintenance and ionic content crucial for plant growth and development. It was concluded that structural and functional alterations in all Cenchrus species were very specific and critical for survival under different environmental stresses. The ecological fitness of these species relied on maintenance of growth and biomass production, and the development of mechanical, vascular, dermal and parenchyma tissues under stressful environmental conditions. Moreover, accumulation of beneficial ions (K+ and Ca2+) and organic osmolytes were critical in turgor maintenance, hence survival of Cenchrus spp. [ABSTRACT FROM AUTHOR]

Context: Allelopathy is recognised as a potential technology to control weeds, and could also be a suitable approach for enhancement of crop yield. Aims: The study was conducted to investigate the allelopathic role of Averrhoa carambola leaf extract on growth, anatomical and physiological features of three wheat lines, namely 3094, 7076 and A2011. Methods: Three dilutions i.e. 0% (control), 15% and 30% of the leaf aqueous extract were applied at 15 day intervals (total five applications) on wheat lines until maturity. Key results: All wheat lines showed differential behaviour to allelochemicals of A. carambola leaf extract. Increased root area was accompanied by a high proportion of storage parenchyma tissues and enlarged vascular bundles in line 3094. Disintegration of root cortical parenchyma and complete transformation of chlorenchyma into sclerenchyma in stem was recorded in all wheat lines, particularly at the highest concentration of leaf extract. Line 7076 showed very different behaviour, as it possessed a proportionally enlarged root cortex, enlarged stem vascular bundles and increased leaf thickness, primarily at the highest concentration of leaf extract. Line A2011 was relatively more sensitive, indicating a significant reduction (P < 0.05) in root and stem area and deformed leaves. Conclusions: A low concentration (15%) of leaf extract promoted growth and development, whereas a higher concentration caused significant reduction in growth and anatomical attributes. Implications: A lower dose of Averrhoa leaf extract promoted growth and development in all wheat lines, and hence can be used as a growth promoter. A higher concentration is important for eradicating unwanted plants. Wheat lines were treated with allelochemicals extracted from A. carambola. A low treatment concentration led to increased root area, accompanied by a high proportion of storage parenchyma tissues, and enlarged vascular bundles. Using a high extract concentration, root cortical parenchyma collapsed while stem chlorenchyma was transformed to sclerenchyma. Line 7076 responded differently, as it possessed an enlarged root cortical proportion, enlarged stem vascular bundles and increased leaf thickness. A low concentration (15%) of leaf extract promoted growth, whereas a higher concentration (30%) caused significant reduction in morpho-anatomical traits. [ABSTRACT FROM AUTHOR]