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    Characteristics and methods to release seed dormancy of two ground cherry (Physalis) species
    (Elsevier, 2021) Farooq, Shahid; Onen, Huseyin; Ozaslan, Cumali; El-Shehawi, Ahmed M.; Elseehy, Mona M.
    Several ground cherry (Physalis) species have attracted significant interest due to their potential use in medicines. Nonetheless, these species are invasive weeds in some regions of the world, while cultivated for food and medicinal uses in the others. Physalis angulata is cultivated for its medicinal potential, whereas P. philadelphica is grown as a horticultural crop. Both species are regarded as invasive weeds in Turkey causing significant economic losses. These species are underutilized in the country and could serve as a valuable resource for agriculture and medicine industries. Therefore, we investigated the seed dormancy type, levels and methods of dormancy release for P. angulata and P. philadelphica. Seeds of different populations of both species (3 population per species) were collected from various elevation gradients in southeastern Anatolia region, Turkey. Numerous seed dormancy-release techniques were evaluated to understand the requirements for dormancy release. Significant differences were observed in seed dormancy level among species and their populations, while viability remained similar. Seeds P. angulata had higher dormancy level (73.07-98.78 % dormancy) than P. philadelphica (7.56-33.15 % dormancy). The level of seed dormancy was increased with increasing elevation gradient in both species. There were some germination inhibiting substances, which retarded seed germination of both species. This indicated that the dormancy type in both species belongs to physiological dormancy (PD). Running tap water proved the most effective treatment in releasing seed dormancy of all tested populations. Some of the dormancy breaking techniques, especially scarification with H2SO4, even suppressed germination. The knowledge of seed dormancy could be utilized to commercialize/cultivate both species in Turkey. Nevertheless, the result could also be used for the development of management strategies against the species where these are considered as invasive weeds.
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    Germination Biology of Two Invasive Physalis Species and Implications for Their Management in Arid and Semi-arid Regions
    (Nature Portfolio, 2017) Ozaslan, Cumali; Farooq, Shahid; Onen, Huseyin; Ozcan, Selcuk; Bukun, Bekir; Gunal, Hikmet
    Two Solanaceae invasive plant species (Physalis angulata L. and P. philadelphica Lam. var. immaculata Waterfall) infest several arable crops and natural habitats in Southeastern Anatolia region, Turkey. However, almost no information is available regarding germination biology of both species. We performed several experiments to infer the effects of environmental factors on seed germination and seedling emergence of different populations of both species collected from various locations with different elevations and habitat characteristics. Seed dormancy level of all populations was decreased with increasing age of the seeds. Seed dormancy of freshly harvested and aged seeds of all populations was effectively released by running tap water. Germination was slightly affected by photoperiods, which suggests that seeds are slightly photoblastic. All seeds germinated under wide range of temperature (15-40 degrees C), pH (4-10), osmotic potential (0 to -1.2 MPa) and salinity (0-400 mM sodium chloride) levels. The germination ability of both plant species under wide range of environmental conditions suggests further invasion potential towards non-infested areas in the country. Increasing seed burial depth significantly reduced the seedling emergence, and seeds buried below 4 cm of soil surface were unable to emerge. In arable lands, soil inversion to maximum depth of emergence (i.e., 6 cm) followed by conservational tillage could be utilized as a viable management option.
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    Higher Tolerance to Abiotic Stresses and Soil Types May Accelerate Common Ragweed (Ambrosia artemisiifolia) Invasion
    (Cambridge Univ Press, 2017) Onen, Huseyin; Farooq, Shahid; Gunal, Hikmet; Ozaslan, Cumali; Erdem, Halil
    Common ragweed is a troublesome allergenic invader and noxious weed of several crops. Despite extensive research to understand the factors affecting its invasion, the role of environmental stresses and soil types on survival and growth is poorly understood. The objective of this study was to determine the effects of drought, salinity, and soil types on survival, growth, and nutrient uptake of ragweed in greenhouse experiments to predict its invasiveness in Turkey. Three separate experiments, with five drought intensities (100, 75, 50, 25, and 12.5% of field capacity [FC]), four levels of salinity (0, 3, 6, and 12 dS m(-1)), and five soil types varying in sand, silt, and clay content were performed. Severe drought and salinity levels reduced seedling survival, while soil type had no effect. Increasing drought and salinity negatively affected growth and nutrient uptake; the poorest growth was observed under severe drought intensity. Ragweed exhibited intensive tolerance to drought, even severe levels, while it tolerated salinity up to 6 dS m(-1) for seedling survival. Growth was negatively affected above 3 dS m(-1). The highest and lowest nutrient accumulations were recorded under moderate and extreme drought intensities, respectively. Similarly, the highest Na accumulation was observed under extreme saline conditions, whereas the highest P uptake and K/Na ratio were achieved under nonsaline conditions (0 dS m(-1)). Variation of soil texture had no effect on growth and nutrient uptake. The highest Ca, Mg, and Na accumulations were recorded on clay soil, while higher P accrued on sandyloam soil. Increased tolerance of ragweed to severe drought and moderate salinity and its nonselective nature for soil type indicate that semiarid and partially arid regions in Turkey have plenty of vacant niches for ragweed invasion.
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    The Influence of Environmental Factors on Germination of Burcucumber (Sicyos angulatus) Seeds: Implications for Range Expansion and Management
    (Cambridge Univ Press, 2018) Onen, Huseyin; Farooq, Shahid; Tad, Sonnur; Ozaslan, Cumali; Gunal, Hikmet; Chauhan, Bhagirath S.
    Burcucumber (Sicyos angulatus L.) is a highly invasive vine that has become naturalized in the humid Black Sea region of Turkey, but previous to this study there was no information on the germination biology of this weed. The germination biology of three naturalized populations of S. angulatus from the Black Sea region was studied in laboratory and greenhouse experiments. The germination of nondormant seeds was observed under different photoperiods, constant temperatures, and varying levels of pH, salinity, and osmotic potential. Furthermore, seedling emergence from various soil depths was investigated. The seeds of all populations proved nonphotoblastic (82% to 90%, 55% to 66%, and 48% to 56% germination under 12-, 24-, and 0-h photoperiod, respectively) and germinated over a wide range of temperatures (5 to 40 C). Seedlings emerged from all seed burial depths (0 to 15 cm); however, germination was drastically reduced (>90% reduction) beyond 6 to 8 cm. Seed germination was 30% to 38% for seeds placed on the surface and increased to 78% to 88% for seeds buried 2 cm deep, while germination was severely reduced for seeds buried 10 and 15 cm deep (8 to 12% and 0 to 6%, respectively). Seeds of all populations were found to be sensitive to osmotic and salinity stress and to highly acidic and alkaline pH levels. All populations had similar requirements for germination that are directly related to their area of naturalization. These results indicate that the species has limited potential for range expansion to arid, semiarid (nonirrigated), and relatively saline areas. However, humid, salinity-free, and frequently irrigated areas of the country are at high risk of invasion. In arable lands, deep tillage followed by shallow tillage and effective management of emerging seedlings could deplete the soil seedbank in the long run. However, there is an urgent need for effective strategies to manage the species in other nonarable areas.
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    Invasion Potential of Two Tropical Physalis Species in Arid and Semi-Arid Climates: Effect of Water-Salinity Stress and Soil Types on Growth and Fecundity
    (Public Library Science, 2016) Ozaslan, Cumali; Farooq, Shahid; Onen, Huseyin; Bukun, Bekir; Ozcan, Selcuk; Gunal, Hikmet
    Invasive plants are recognized for their impressive abilities to withstand adverse environmental conditions however, all invaders do not express the similar abilities. Therefore, survival, growth, nutrient uptake and fecundity of two co-occurring, invasive Physalis species were tested under water and salinity stresses, and different soil textures in the current study. Five different water stress levels (100, 75, 50, 25, and 12.5% pot water contents), four different soil salinity levels (0, 3, 6, and 12 dSm(-1)) and four different soil textures (67% clay, 50% clay, silt clay loam and sandy loam) were included in three different pot experiments. Both weeds survived under all levels of water stress except 12.5% water contents and on all soil types however, behaved differently under increasing salinity. The weeds responded similarly to salinity up till 3 dSm(-1) whereas, P. philadelphica survived for longer time than P. angulata under remaining salinity regimes. Water and salinity stress hampered the growth and fecundity of both weeds while, soil textures had slight effect. Both weeds preferred clay textured soils for better growth and nutrient uptake however, interactive effect of weeds and soil textures was non-significant. P. angulata accumulated higher K and Na while P. philadelphica accrued more Ca and Mg as well as maintained better K/Na ratio. P. angulata accumulated more Na and P under salinity stress while, P. philadelphica accrued higher K and Mg, and maintained higher K/Na ratio. Collectively, highest nutrient accumulation was observed under stress free conditions and on clay textured soils. P. philadelphica exhibited higher reproductive output under all experimental conditions than P. angulata. It is predicted that P. philadelphica will be more problematic under optimal water supply and high salinity while P. angulata can better adapt water limited environments. The results indicate that both weeds have considerable potential to further expand their ranges in semi-arid regions of Turkey.
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    Range expansion potential of two co-occurring invasive vines to marginal habitats in Turkey
    (Elsevier, 2017) Farooq, Shahid; Tad, Sonnur; Onen, Huseyin; Gunal, Hikmet; Caldiran, Ugur; Ozaslan, Cumali
    Niche distribution models accurately predict the potential distribution range of invasive plants into new habitats based on their climatic requirements in the native regions. However, these models usually ignore the marginal habitats which can limit the distribution of exotic plants. We therefore tested the seedling survival, growth and nutrient acquisition capabilities of two co-occurring invasive vines [Persicaria perfoliata (L.) H. Gross and Sicyos angulatus L.] in three different manipulative greenhouse experiments to infer their range expansion potential to marginal habitats in Turkey. First experiment included five different moisture availability regimes (100, 75, 50, 25 and 12.5% available water), second experiment consisted of four different salinity levels (0, 3, 6 and 12 dSm(-1) soil salinity) and third experiment had four different soil textures (clay-1, clay-2, sandy loam and silt-clay-loam). Seedling mortality was only observed under extreme moisture deficiency in both plant species, while most of the transplanted seedlings of both species did not survive under 6 and 12 dSm(-1) salinity levels. Soil textures had no effect on seedling survival. POLPE better tolerated low moisture availability and high salinity Compared to SIYAN. Biomass production in both plant species was linearly reduced with increasing salinity and moisture deficiency. SIYAN invested more resources towards shoot, accumulated higher K and P, whereas POLPE maintained higher root-to-shoot ratio under all experimental conditions. Both plant species employed different strategies to cope with adverse environmental conditions, but failed to persist under high soil salinity and moisture deficiency. Our study suggest that both plant species have limited potential of range expansion to marginal habitats and will be limited to moist and humid areas only. Therefore, further research activities should be concentrated in these regions to develop effective management strategies against both species. (C) 2017 Elsevier Masson SAS. All rights reserved.