In Vitro Screening of Indica Rice Genotypes for Drought Tolerance Using Polyethylene Glycol

Abstract

Abstract-Rice (Oryza sativa L 2n=24), one of the three major food crops of the world, covers 11 per cent of the arable land in the world. One of the main constraints of rice cultivation and production is drought, which affects the vegetative growth rate and grain yield. The present investigation was carried out to study the drought tolerance of 50 indica rice genotypes including 24 modern varieties, 16 rice cultures and ten traditional varieties along with the drought tolerant check varieties PMK 3 and MDU 5. The 50 rice genotypes were screened in in vitro bioassay method by using Polyethylene glycol (PEG 6000 MW) to assess their seedling response under drought. Drought stress was simulated at four different concentrations namely, -3.0, -5.0, -7.5 and -10.0 bars of water potential by dissolving 115, 196, 235 and 289 grams of PEG 6000 respectively in 1000 ml of distilled water. A control (0.0 bar) was maintained using distilled water The experiment was laid in completely randomized design with two replications. Data were recorded on germination percentage, root length, shoot length and root / shoot ratio at four different levels of treatment. Screening of the 50 rice genotypes for tolerance to drought at seedling stage using various concentrations of PEG 6000 resulted in the identification of nine rice genotypes namely, G3, G19, G21, G24, G25, G31, G35, G49 and G50 with tolerance to drought. The in vitro screening of rice seedlings using PEG 6000 can be adjudged as a simple, rapid and preliminary bioassay that can be used in mass screening for evaluating seedling of rice genotypes under drought.Index Terms-Drought, in vitro screening, PEG, Rice I. INTRODUCTION Drought is one of the major limiting factor that affects rice productivity in Asia [9]. It is estimated that by 2025, 15 million hectares of irrigated land and 22 million hectares in Asia will be under physical and economic water scarcity respectively [12].The percentage of drought affected land in the world has more than doubled since 1970s [4]. Early and rapid root elongation is an important indicator of drought tolerance and root length is more affected than shoot length under drought. Screenings for drought tolerance at seedling stage using osmotic solutions is reported as one of the robust methods to study resistance during germinal phase by [8] and [11]. With this background, the present study was undertaken to evaluate the drought tolerance of the 50 rice genotypes at seedling stages using polyethylene glycol 6000 (PEG 6000). II. MATERIALS AND METHODS A. Genetic materialsExperimental material comprised of fifty genotypes with broad genetic base involving 24 modern varieties, 16 rice cultures and ten traditional varieties along with the drought tolerant check varieties PMK 3 and MDU 5. B. Laboratory experimentThe experiment was conducted at the Abiotic Stress Laboratory of Department of Genetics and Plant Breeding, Faculty of Agriculture during August, 2014. The in vitro screening for drought tolerance was carried out using Polyethylene Glycol (PEG ...

Combining ability of anther culture response in some rice crosses under drought stress conditions

“…Also, highly significant mean squares due to the interaction of genotypes, parents, crosses, line, tester and line × tester with PEG treatments were detected for all the studied traits except albino plant regeneration, indicating that these genotypes varied in their response to PEG stress levels for most of the studied traits. These results are in agreement with those obtained by Akte et al (2016), and Sabesan and Saravanan (2016). Parent vs. crosses mean squares (Table 1) as an indication to average heterosis overall crosses were found to be highly significant for all the studied traits under the four stress levels and the combined data.…”

In-vitro selection of drought tolerant doubled haploid rice lines using polyethylene glycol (PEG)

“…The lines showing root response together with drought tolerant check (Dagaddeshi and RRF-27) and parent (IR-158) at -7.5 bar and -10 bar of external water potential induced by PEG indicate drought tolerance. Similar to present study, several studies reported that the increased in PEG concentration leads to the root length deployment when compared with control (Jajarmi, 2009;Khakwani et al, 2011;Govindaraj et al, 2010;Sabesan and Saravanan, 2016;Akte et Effect of water stress on shoot/root ratio In addition to root length and shoot length, shoot to root ratio plays a major role in selecting drought tolerant lines. The interdependence of shoot and root is required for the optimal growth and development of the crop.…”

“…Rest of the lines didn't produce any kind of shoot growth indicate drought susceptibility. Previous studies on PEG treatment in different crops reported that the increase in external water potential leads to the decrease in shoot length when compared with control (Jajarmi, 2009;Khakwani et al, 2011;Govindaraj et al, 2010;Sabesan andSaravanan, 2016, Mansour andElbagrmi, 2019). Masour and Elbagrmi, 2019 reported slight increase in shoot length at level of -3 bar in 3 wheat cultivars and then reduced with the increase in PEG concentration.…”

“…Similarly, Akte et al, 2016 reported decrement in shoot length from 15.76 cm in control to 15.76 cm in 4% PEG concentration in rice varieties. Decrement in shoot length with the increase in PEG concentration is due to decrease in turgor pressure resulting in reduced cell division and cell elongation (Lagerwerff et al, 1961;Chandra, 2011;Nurhayati et al, 2017;Akte et al, 2016;Sabesan and Saravanan, 2016). The water scarcity can in induced by PEG because it may cause effect on metabolic processes of plant via preventing nutrients transfer (Chandra, 2011;Govindaraj et al, 2010).…”

“…These seeds were placed in petri dish on to the moistened blotting paper for germination. After 3 days of germination, drought stress was induced in vitro using PEG (PEG6000) at 0.0 bar, -5.0, -7.5 and -10.0 bars of external water potential which was prepared by dissolving 196, 235 and 289 grams respectively in 1000 ml of distilled water (Hadas, 1976;Sabesan and Saravanan, 2016). After 10 days of PEG treatment, data were recorded at different level of external water potential on seedling traits such as root length, shoot length and root/shoot ratio.…”