Effect of Different Water Salinity Levels on the Germination of Imazamox-Resistant and Sensitive Weedy Rice and Cultivated Rice

Abstract

Weeds that have become resistant to herbicides may threaten rice production. Rice cultivation is mainly carried out in coastal and river delta areas that often suffer salinity problems. The aims of this study were to evaluate the effects of salinity upon germination and the root and shoot seedling growth of Italian weedy rice and cultivated rice (Oryza sativa), and to find a possible correlation between salinity and herbicide resistance. Seed germination tests were conducted in Petri dishes on four imazamox-sensitive and one resistant weedy rice populations and two rice varieties: Baldo (conventional) and CL80 (imidazolinone-resistant Clearfield® variety). Different salt concentrations were tested: 0, 50, 100, 150, 200, 250, 300, 350 and 400 mM NaCl. Germination percentage, germination speed, seedling root and shoot length were affected by increasing the salt concentration in all tested populations and varieties. The germination percentage was in general more affected in resistant weedy rice and CL80. In resistant weedy rice this was partially compensated by a faster germination up to 100 mM. In terms of seedling root and shoot length, CL80 and Baldo showed the highest tolerance to salt; resistant weedy rice was not able to produce seedling roots and shoots at concentrations > 300 mM.

Molecular Manipulation of the miR399/PHO2 Expression Module Alters the Salt Stress Response of Arabidopsis thaliana

“…Once taken up by the root system, the salt ions are further concentrated in the aerial tissues of a plant to interfere with numerous molecular, biochemical and physiological processes [4][5][6]9]. Moreover, a high abundance of salt ions in the aerial tissues not only leads to ionic toxicity, but can also enhance osmotic pressure, reduce turgor pressure, and promote the generation of reactive oxygen species (ROS), with elevated levels of ROS leading to the onset of oxidative stress [11][12][13]. Together, this promotes the closure of leaf stomata, reduces the rate of photosynthesis, decreases the uptake of nutrients and water from the soil, and represses carbon assimilation, all of which a unique response at the molecular level with the abundance of the central miR399/PHO2 expression module components, the miR399 and PHO2 transcripts, altered to differing degrees.…”

Sensitivity to salinity at the emergence and seedling stages of barnyardgrass (Echinochloa crus-galli), weedy rice (Oryza sativa), and rice with different tolerances to ALS-inhibiting herbicides

“…with herbicide resistance, even though specific studies are needed to confirm this hypothesis (Keshtkar et al 2019). Greater growth performance and higher competitive ability of herbicide-sensitive populations were also reported in a previous germination study on O. sativa and rice, while similar competitive ability was observed when comparing E. crus-galli populations resistant and sensitive to propanil and clomazone (Bagavathiannan et al 2011;Fogliatto et al 2019). However, previous studies carried out with other species that are resistant to different herbicides found a higher growth performance and tolerance to salt in resistant populations (Shrestha et al 2018).…”

“…According to some studies, E. crus-galli is considered to be able to cope with high-saline conditions, probably because this species is able to take up potassium more selectively than sodium (Wilson and Read 2006). The salt tolerance of E. crus-galli is generally higher than that of many other crops, such as rice, and other weeds, like O. sativa (Fogliatto et al 2019;Hakim et al 2011;Serra et al 2018). Echinochloa is also one of the genera most prone to developing herbicide resistance; it has been demonstrated that different populations of E. crus-galli have become resistant to eight site-ofaction herbicides used in rice throughout the world and, in particular, to acetolactate synthase (ALS) and acetyl-CoA carboxylase (ACCase) inhibitors (Heap 2020).…”

“…Many studies have been conducted to determine the level of rice's tolerance to salt, although only a few studies have been carried out to establish the effect of salinity on weed growth (Chauhan et al 2013;Fogliatto et al 2019;Hakim et al 2011;Serra et al 2018). Moreover, the growth behavior of herbicide-resistant and herbicide-sensitive weeds under saline conditions has been investigated even less (Fogliatto et al 2019;Serra et al 2018).…”

Molecular Manipulation of MicroRNA397 Abundance Influences the Development and Salt Stress Response of Arabidopsis thaliana

“…Soil salinity is toxic to most crop species because it inhibits the conventional growth and development of these species by interfering with numerous molecular and physiological processes. Namely, the excessive accumulation of salt in plant tissues can rapidly lead to high osmotic pressure, loss of turgor pressure, ionic (sodium, Na + , and chloride, Cl − , ions) toxicity, and reactive oxygen species (ROS)-derived oxidative stress [ 8 , 9 , 10 ]. This results in the closure of stomata, cessation of cell growth and expansion, reduction in the rate of photosynthesis, reduced carbon assimilation, and the uptake of water and nutrients, which together promote the premature transition from vegetative to reproductive development and the early onset of senescence [ 11 , 12 ].…”