Estimation and Selection of Parental Forms for Breeding Kazakhstan Salt Tolerant Rice Varieties

Abstract

A b s t r a c tAbout 25 % of the entire land surface is represented by saline soils, and up to 90 % of the total irrigated area -in some regions of Central Asia and the Caucasus, Ukraine and Kazakhstan. Rice-growing region of the Republic of Kazakhstan is also located in the area with high salinity. A challenge for rice growing in Kazakhstan is deteriorating humus and reclamation of soil, rise in soil secondary salinity and degradation. In Kyzylorda region, pollution of surface (up to 3-5 g/l) and ground water (up to 6-7 g/l) by salt residues reaches a critical point. The dominating sulfatechloride-sodium type of salinity is especially toxic for crops. Akdalinski and Karatal zones of irrigation in the Almaty region are also located within the provinces of sulfate-soda and boric biogeochemical soil salinity. According the data of Kazakh Rice Research Institute, in recent years the rice yields and yield quality have sharply decreased -from 50 to 35-48 centners per hectare, and from 65 to 45-50 % of the groats output, respectively. In this regard, the rice breeding for salt tolerance is the most important to ensure food security in Kazakhstan. The objective of our study was the evaluation and selection a promising starting material of rice resistant to different types of salinity. To this end, we studied the rice (Oryza sativa L.) varieties, collection samples and their hybrid combinations of different generations derived from Russia, Kazakhstan and Philippine (34 genotypes in total). For the initial assessment at the seedling stage we used the laboratory screening for tolerance to various types of salinity, i.e. chloride, sulphate and carbonate. Saline stress negatively affected seedling growth and total weight in the studied samples. It was revealed that the carbonate type of salinity is the most toxic for rice plants; the chloride and sulfate types were less adverse. The hybrid collection sample F 2 Khankai 429 ½ 4-09 and as well as varieties Marzhan and Madina accumulated the highest percentage of biomass compared to the control at the salinity of all three types. Therefore, these genotypes are valuable in selection for salt tolerance. Molecular screening of chromosomal DNA regions linked to quantitative trait loci of salt tolerance (Saltol QTL) by PCR with microsatellite markers closely linked to the target chromosomal regions, RM 493 and AP 3206, showed RM 493 to produce polymorphism which allowed to distinguish the studied genotypes contrasting in salt tolerance. Thus RM 493 is informative to rank the rice genetic plasma by salt tolerance.Keywords: Oryza sativa L., rice, chloride salinity, sulfate salinization, carbonate salinity, molecular screening for salt tolerance, SSR markers, selection About 950 million hectares of agricultural lands in the world are saline,