Abstract
AbstractSalinization is affecting many rice (Oryza sativa L.) areas worldwide and weed infestation, together with the occurrence of herbicide-resistant populations, is further limiting rice yield. This study aimed at evaluating the effect of water salinity on the emergence and seedling growth of five Italian barnyardgrass [Echinochloa crus-galli (L.) P. Beauv.] populations (three sensitive and two resistant to acetolactate synthase–inhibiting herbicides), three Italian weedy rice (Oryza sativa L.) populations (all sensitive to imazamox), and two rice varieties (the conventional ‘Baldo’ variety and the imazamox-tolerant ‘CL80’ one). In 2017, seeds were sown in alveolar trays filled with sand, a nutrient solution, and water with the following salt concentrations: 0, 50, 100, 150, 200, and 250 mM NaCl. Plant emergence (after 15 d), plant height, shoot and root weight, chlorophyll a, chlorophyll b, and carotenoid content were measured at 40 d after sowing. Echinochloa crus-galli showed a higher tolerance to salinity than O. sativa and rice. All species were affected more at the seedling stage than at emergence. A variable behavior of the herbicide-resistant populations was shown; one resistant E. crus-galli population was affected more by salinity and showed a lower emergence rate (about 20% against 40% emergence of the other populations at the highest salt concentration) and reduced seedling growth, while the other resistant population’s response was similar to that of the sensitive populations. The chlorophyll content increased as the salt content increased in all E. crus-galli populations. The highest emergence and growth reduction in O. sativa were recorded in the imazamox-tolerant rice. Rice and O. sativa were able to grow only up to 50 mM. Echinochloa crus-galli populations are probably favored under saline conditions, while lower infestation by O. sativa can be expected.
Highlights
Environmental stresses, such as high and low temperatures, drought, salinity, alkalinity, and high CO2 concentrations, are able to influence the growth of plants (Ahuja et al 2010).Salinity represents one of the main environmental stresses that can affect plant growth and cause crop yield reductions (Negrão et al 2017; Parihar et al 2015)
Seeds from E. crus-galli populations were collected in August 2016 from Italian rice fields located in different zones of the main area of rice cultivation in Italy that have similar climatic conditions; the fields had a history of repeated applications of the acetolactate synthase (ALS)-inhibiting herbicide penoxsulam
The regression analysis carried out on plant emergence for different salt concentrations established that emergence decreased in all E. crus-galli populations for increasing salt levels, albeit at different magnitudes (Figure 1)
Summary
Environmental stresses, such as high and low temperatures, drought, salinity, alkalinity, and high CO2 concentrations, are able to influence the growth of plants (Ahuja et al 2010). Salinity represents one of the main environmental stresses that can affect plant growth and cause crop yield reductions (Negrão et al 2017; Parihar et al 2015). The effects of salinity on plant growth are gaining importance because salinization areas are increasing throughout the world, mainly as a consequence of the overexploitation of water resources and climate change (Akbari et al 2020; Kibria et al 2017; Singh 2018). The presence of salt in these areas can be an obstacle to the growth of various crops, such as rice (Oryza sativa L.), because of its toxicity and because of osmotic stress that can alter the water uptake potential/dynamics of plants (Kibria et al 2017)
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