On the problem of grain damage in the form of dark spots in field conditions when cultivating rice in Krasnodar region

Abstract

The analysis of grain damage in the form of dark spots of Russian rice varieties grown in Krasnodar region in 2011-2020 has been carried out. Rice grain was damaged during the filling period, mainly in full ripeness. The high degree of damage was the reason for the deterioration of grain quality. The degree of damage varied over the years. 2011 and 2012 were characterized by a high content of damaged grains (up to 3-20%). The degree of damage to rice grain was different in different agar-landscape zones of Krasnodar region: in the Krasnoarmeysky district it was higher than in the Abinsky. On panicles of variety Rapan without stinkbugs, one caryopsis with damage was found, while on panicles with stinkbugs, their number increased to 12.4-20.3%. In variety Kurazh, damage to caryopses in the form of dark spots on panicles with stinkbugs reached 10.1-19.1%. A significant increase in the degree of damage to rice grain stored in storage began in 2011. In 2011, the content of damaged grains increased by more than 1%, in 2012 it reached 8.3% in the Slavyansky district. Since 2013, the degree of damage to rice grain in the field began to decrease. It is concluded that the damage is associated with the pathogenic effect on the plant and the caryopsis of bug insects with a piercing-sucking mouth apparatus. Damage to caryopses was insignificant in 2015-2020.

Rice Grain Dark Spots and Their Impact on Quality Associated Traits

“…In 2012, due to climatic conditions, the turtle, bugs, locusts, and meadow moths became active earlier than usual, and a state of emergency was declared in the Russian regions of Volgograd, Saratov, Samara, Astrakhan, Orenburg, Kalmykia, Dagestan, and Stavropol regions. In the Krasnodar region, Russia, in 2012, the significant damage to rice yield rose to 20%-30%, which led to a decrease in rice cultivation profitability (Tumanyan et al, 2021).…”

“…After a thorough examination of damaged rice seeds, the detected representatives of the fungal microflora included, i.e., Alternaria tenuis, Trichothecium sp., and Fusarium moniliforme, and in small quantities -Penicillium sp., Rhizopus sp., Aspergillus flavus orizae, Cladosporium sp., Phoma sp., and Drechslera hawaiiensis (IRRI, Philippines; Fanyan et al, 2002;Kumeiko and Tumanyan, 2020). Grain damage in the form of dark spots leads to a decrease in yield quality in varying degrees (Patel et al, 2006;Lang et al, 2020;Tumanyan et al, 2021). In the United States, Venezuela, Mexico, Brazil, Cuba, and the Caribbean, the main pests responsible for dark spots on caryopsis are Oebalus pugnax, Oebalus insularis Stål, Oebalus poecilus, and Oebalus ypsilongriseus, with the intensity of yield damage depending on the distribution of insects (Dallas, 1851;Walker, 1990;Pantoja et al, 1995;McPherson and McPherson, 2000;Zachrisson et al, 2014).…”