Arsenıc tolerance ın rıce: a comparatıve study on germınatıon and early growth stage

The purpose of this study was found out to investigate the response of some rice (Oryza sativa L.) cultivars to germination parameters under salinity stress. This study was carried out to confirm rice seedling growth performance and to examine a range of genetic variability for salinity tolerance among ten rice cultivars under seven salinity levels. A laboratory experiment was accompanied at Giza Central Seed Testing laboratory (CASC), Egypt. The results showed that rice cultivars significantly varied in means of Final Germination Percentage (FGP), Germination Rate (GR), Germination Index (GI), Vigor Index (VI), Root Length, Shoot Length, Root Fresh Weight, Shoot Fresh Weight, Root Dry Weight, Relative Dry Weight and Seedling Height Reduction. Sakha 102 and Sakha 106 had positive effects in most of studied characters while, Giza 181 cultivar had negative effects in most of germination parameters under study. Salinity levels significantly varied in all germination parameters under study except shoot dry weight character. Increasing salinity concentration from 0 to 14% NaCl gradually reduced averages of germination and seedling characters. All studied characters were significantly affected by the interaction between cultivars and salinity stress, vice versa, shoot, root fresh weight and root dry weight didn't affect by interaction. It could be established that for exploiting rice germination percentage and seedling parameters under salinity stress are recognized by using rice Sakha 102, Sakha 106, Sakha 104 and Egyptian Yasmin cultivars with increasing salinity levels up to 14% NaCl. These cultivars were more tolerant to salinity and suggested to use in breeding program for attractive rice production in Egypt . Key wordsOryza sativa, salinity concentration, germination characters, rice cultivars, seedling parameters International Journal of Agriculture Sciences ISSN: 0975-3710 & E-ISSN: 0975-9107, Volume 4, Issue 6, 2012 Introduction Rice is considered as a major cereal crop for more than 50% of the world population. There is a great shortage in rice production more than 25% of the recent production may be needed [1]. Moreover, rice ranks second after wheat crop as the national income is concerned. The excessive increase in population in Egypt needs to increase the total yield of this crop in order to overcome this lack in production through its cultivation in the newly reclaimed lands especially under saline conditions of such soil. Rice is one of the most effective and commercial means of reclaiming hundreds of thousands of hectares of saline lands in Egypt. Growth characters including shoot height, fresh weight, dry weight and leaf area of salt-stressed seedlings were inhibited, depending on rice genotypes [2]. Rice varieties showed a great variation in germination due to salinity effects. Many investigators concluded that differences among rice cultivars in germination characters and seedling parameters[3,15,17,22]. Salinity is one of the major obstacles in enhancing rice production in growing areas in Egypt. Salinity decreases final germination percentage, speed of germination and led to reduction in shoot and root length and dry weight in all varieties and the magnitude of reduction increased with increasing salinity stress [11]. Therefore, development of salt tolerance varieties has been considered as one of strategies to increase rice production in saline prone Citation: Kandil A.A., Sharief A.E. and Nassar E.S.E. (2012) Response of Some Rice (Oryza sativa L.) Cultivars to Germination Under Salinity Stress. International Journal of Agriculture Sciences, ISSN: 0975-3710 & E-ISSN: 0975-9107, Volume 4, Issue 6, pp-272-277. Copyright: Copyright©2012 Kandil A.A., Sharief A.E. and Nassar E.S.E. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution and reproduction in any medium, provided the original author and source are credited.

The ever-increasing demand for rice raises the need to increase productivity by developing drought-tolerant rice varieties. Drought tolerance is a complex polygenic trait that largely depends upon plant developmental stages and showed genotype-specific variability. The experiment was conducted using drought tolerant (Binadhan-19, BRRI dhan83) and drought susceptible (BRRI dhan26, BRRI dhan48) rice genotypes at the glasshouse of Bangladesh Institute of Nuclear Agriculture (BINA), Mymensingh to characterize the seedling stage drought tolerance as well as disclose the variability of the genotypes for morphological and biochemical traits. A completely randomized design (CRD) with three replications and treatments (control and drought stress imposed by 20% PEG) was used for the experiment. Data on shoot length, root length, fresh root weight, fresh shoot weight, dry root weight, dry shoot weight, chlorophyll content (SPAD value), MDA, and H2O2 were recorded and analyzed through appropriate breeding tools. Significant variation (p<0.01) was observed for genotype, treatment, and genotype (G) × treatment (T) interactions viz., shoot length, root length, root fresh weight, shoot fresh weight, root dry weight, shoot dry weight, chlorophyll, H2O2, and MDA. Drought stress leads to a significant decrease in root and shoots growth whereas the level of H2O2 and MDA increased significantly. A greater decrease in root and shoot growth was observed in susceptible genotypes (BRRI dhan28, BRRI dhan48) compared to tolerant genotypes (BRRI dhan71, Binadhan-19). In contrast, a limited increase in H2O2 and MDA was recorded in tolerant genotypes compared to susceptible genotypes. H2O2 showed a significant positive correlation with root and shoot characteristics under control conditions, whereas H2O2 showed a significant negative correlation with chlorophyll content under drought conditions. MDA showed a significant negative correlation with most of the studied traits under well-watered conditions. Considering all of the traits at the seedling stage, the genotype Binadhan-19 is considered a drought-tolerant genotype both under well-watered and drought conditions, and this genotype was selected for further study under direct field conditions as well as for genetic improvement against drought stress.

The experiment was carried out in the Seed Laboratory of Bangladesh Agricultural Development Corporation (BADC), Gazipur during June to July 2014 to investigate the effects of different priming methods on seed germination and the seedling growth of some rice (Oryza sativa L.) varieties. Four rice varieties: 1) Nerica, 2) BRRI dhan51, 3) BRRI dhan41 and 4) BRRI dhan49; and six priming treatments: 1) On-farm Priming, 2) Hardening, 3) Hydro-priming, 4) Osmo-hardening, 5) Vitamin C Priming and 6) Control were used in the experiment. The experiment was laid out in a completely randomized design (CRD). The treatments were replicated three times. The germination percentage and seedling growth parameters differed significantly among the priming treatments. For germination, Nerica variety showed poor performance, whereas the other varieties were found superior. Among the priming treatments, Vitamin C priming and Osmo-hardening were found superior. In case of interaction, germination was increased with Vitamin C priming and Osmo-hardening in Nerica. For seedling growth parameters, particularly vigor index, shoot and root lengths, BRRI dhan41 and BRRI dhan51 were found superior. The priming treatment Vitamin C and Osmo-hardening performed better than others. Seedling vigor index was increased with Vitamin C priming and Osmo-hardening in Nerica variety. Shoot length at 15th day was influenced by hydro-priming in Nerica. Root length at 10th day was significantly increased with hardening in BRRI dhan41. Vitamin C priming and Osmo-hardening could therefore, be used for improving germination and seedling growth of Nerica. The Agriculturists 2018; 16(1) 34-43

To explore the possibility of using methyl jasmonate (MeJA) for alleviation of salt stress, the present study was conducted where six rice varieties (BRRI dhan31, BRRI dhan46, Gota, Kajalsail, Pokkali and Pengek) were grown in non saline (0 dSm-1), saline (12 dSm-1), saline (12 dSm-1) + 10 ?M MeJA and saline (12 dSm-1) + 20 ?M MeJA conditions at germination stage (till the 9 days). MeJA was applied by imbibing seeds in it for 24 hours. To evaluate the effect of MeJA on saline stressed plant at germination stage, change in growth parameters namely germination percentage, shoot and root length, fresh and dry wt. of shoot, fresh and dry wt. of root and biochemical component- activity of alpha-amylase were monitored. Salinity had a minimum effect on final germination percentage (FGP) of rice varieties, but delayed in attaining it. MeJA had least positive effect. Salinity significantly reduced the shoot and root length, fresh and dry weight of all the varieties. MeJA had more decreasing effect in susceptible varieties while increasing effect in moderately tolerant and tolerant. Activity of alpha-amylase in germinated seed varied from 0.051 mg to 0.111 mg mal./mg tissue. At 12dSm-1 salinity, susceptible and moderately tolerant varieties showed significant reduction but tolerant showed significant increase. MeJA intensified the negative effect further in susceptible varieties. In tolerant and moderately tolerant varieties, increment in activity took place and 10 ?M had a better effect over 20 ?M MeJA.Asian J. Med. Biol. Res. March 2016, 2(1): 74-81

In order to study performance of mungbean to salinity stress, a laboratory experiment was carried out to investigate salinity tolerance of two mungbean varieties (Kawmy-1 and IV 2010) to eight salinity levels i.e. 0, 2, 4, 6, 8, 10, 12 and 14 dS/m of NaCl concen- trations. Mungbean (Vigna radiata (L.) Wilczek) varieties were compared for germination efficiency and seedling characters. Results indi- cated that mungbean IV 2010 variety recorded the highest percentages of final germination, germination index %, seedling vigor index, energy of germination, mean germination time (day), coefficient velocity, abnormal seed percentage, root and shoot length, root fresh and dry weight and seedling height reduction. Whilst, mungbean Kawmy-1 variety recorded the highest weight of fresh and dry shoot and relative dry weight. Highest germination parameters and seedling characters of the two studied varieties under control treatment. The obtained results suggested that the two varieties registered a decrease in the percentage of germination and seedlings growth at higher NaCl concentrations. Results clearly indicated that mungbean Kawme-1 variety appeared to be more tolerant to salt stress than IV 2010 variety recording higher germination parameters and seedling characters. Increasing salinity concentrations significantly reduced germi- nation percentage, seedling vigor index, coefficient of velocity, mean germination time, shoot and root length, shoot and root fresh and dry weight. It could be concluded that germination efficiency i.e. final germination percentage, germination index, energy of germination, mean germination time, abnormal seed percentage, root and shoot length, seedling total fresh and dry weight, dry weight reduction and shoot length reduction were gradually decreased significantly when salinity increased.

Salt stress has detrimental effects on the growth and development of rice seedlings. In the present study we assessed salt-responsiveness of three coastal rice landraces namely Nona-morchi, Kalihytta and Nara. We conducted two factors pot trial that included five rice genotypes (three candidates coastal rice landraces, Binadhan-10 as tolerant check and BRRI dhan48 as sensitive check) against three salinity levels e.g., control (tap water), 6 and 12 dSm-1 of sodium chloride. Study revealed that, at 12 dSm-1 of salinity, Binadhan-10 showed the lowest reduction in shoot length (14.62%), shoot fresh weight (30.04%) and shoot dry weight (33.71%) which was followed by Nona-morchi, Kalihytta, Nara and BRRI dhan48. Two stress tolerance indices e.g., relative water content (RWC) and electrolyte leakage (EL), also support salt-induced responses of these five rice genotypes. At the highest level of salinity (12 dSm-1), the lowest RWC reduction was observed in Nona-morchi (8.20%) which is followed by Binadhan-10 (11.38%), Kalihytta (38.93%), BRRI dhan48 (36.30%) and Nara (36.51%). And, the highest EL increased in Nara (40.06%) which is followed by BRRI dhan48 (22.06%), Kalihytta (21.12%), Binadhan-10 (8.64%) and Nona-morchi (5.87%) compared with their respective controls. Importantly, photosynthetic pigments profile (chlorophyll a, chlorophyll b, total chlorophyll) were increased in Nona-morchi (24.48, 15.22 and 21.87%, respectively) and Binadhan-10 (13.75, 12.50 and 13.41%, respectively) and reduced in Kalihytta (7.89, 19.42 and 11.08%, respectively), Nara (27.76, 31.32 and 28.76%, respectively) and BRRI dhan48 (32.73, 36.97 and 34.02%, respectively) at 12 dSm-1 salinity compared with their respective controls. It is to noteworthy that at 6 dSm-1 of salt stress, shoot length significantly decreased in the sensitive check BRRI dhan48 by 23.07%, Kalihytta by 17.32% and Nara by 11.54%. While, no significant effect of 6 dSm-1 of salt stress was observed in Binadhan-10 and Nona-morchi in case of shoot length, root length, shoot fresh and dry weight, EL and RWC . Among the three coastal rice landraces, Nona-morchi found as highly tolerant and Kalihytta were found as moderately tolerant while Nara was identified as sensitive against salt stress (12 dSm-1). In the future, these identified salt tolerant rice genotypes might be the ideal resource for breeding new salt tolerant rice varietie

Effect of different chemical priming agents on physiological and morphological characteristics of rice (Oryza sativa L.)

The impact of different salinity stresses [0, 6.4, 12.8, 19.2, and 25.6 dS/m (NaCl)] on the final germination percentage, speed of germination, germination capacity, shoot and root length, seedling vigor index, and total plant dry weight of ten rice cultivars at germination and early seedling stages was investigated in this study. Salinity stress significantly decreased the final germination percentage, speed of germination, germination capacity, shoot and root length, and seedling dry weight in all cultivars, with the most severe effects from level 19.2 and 25.6 dS/m NaCl. Rice cultivars were classified as tolerant, moderately tolerant, moderately susceptible, and susceptible based on the reduction of dry matter, which is considered as the most limiting factor at high NaCl concentrations. The cultivars NJ9108, 3Y9H, 6Y9H, XD22, 5W01, and HLYH3 showed greater efficiency in salt tolerance during germination at 19.4 dS/m salinity. While 20H025, 6Y9H, and XD22 at the seedling stage performed better based on their dry weight reduction. The study found that NJ9108 and XD22 may be used to investigate the effects of salinity on the development processes and physiological consequences at the advanced stage of growth, as salt tolerance during germination and the early seedling stage may be varied from the developed stages. The results suggest that tolerant rice cultivars can be used to study the effects of salinity on the development and other physiological impacts at vegetative and reproductive stages. These findings will support salt-tolerant rice cultivars that may be developed for better production in terms of coping with salinity stresses in the germination and early growth stages.

A laboratory experiment was designed to investigate the effects of salinity stress on the germination and early seedling growth of white mustard (Sinapis alba). Three white mustard genotypes (WM1, WM2, and WM3) were germinated between papers moistened with solutions of various NaCl concentrations: 0 (distilled water), 50, 100, 150, and 200 mM. Germination percentage, mean germination time, germination index, root and shoot length, seedling fresh and dry weight, and dry matter were assessed. The results showed that increased salinity caused a significant reduction in germination percentage and index, as well as seedling growth parameters, with genotypic differences. The germination percentage of WM2 was not affected by increasing salinity stress, while it significantly decreased at 200 mM in WM1 and WM3. Seedling growth was more dramatically inhibited by salinity than germination. Increasing salinity resulted in more severe decreases in shoot length than root length. Low levels of NaCl at 50 and 100 mM promoted seedling fresh weight, and dry weight was higher in seedlings exposed to salinity stress. These results showed significant variation among white mustard genotypes for salinity tolerance, with WM2 exhibiting the highest level of tolerance. Generally, white mustard can withstand salinity levels up to 100 mM NaCl during germination and seedling growth. In conclusion, WM2 should be considered as a genetic resource for salinity tolerance and may be the preferred choice for salt-affected areas over other mustard genotypes.

A pot experiment was conducted to study the effect of drought stress on growth and accumulation of proline in five rice varieties namely BRRI dhan-30, BRRI dhan-32, BRRI dhan-34, BRRI dhan-38 and BRRI dhan-56 and to characterize them on the basis of their behavior of drought tolerance. Drought stress caused the decrease of growth like root length, shoot length, root fresh weight, shoot fresh weight, root dry weight, shoot dry weight, the ratio of root-shoot length. Among the rice varieties, BRRI dhan-56 showed the lowest decrease of growth of plant. BRRI dhan-56 showed the least decrease of water content in both root and shoot. On the other hand, the accumulation of proline was increased in five rice varieties under stress. BRRI dhan-56 showed the highest (3.7- folds) increase in the accumulation of proline in leaf under stress. This study suggests that BRRI dhan-56 may possess drought tolerance characteristics while BRRI dhan-30, BRRI dhan-32, BRRI dhan-34 and BRRI dhan-38 may be drought sensitive based on their growth and proline accumulation behavior. Asiat. Soc. Bangladesh, Sci. 45(2): 241-247, December 2019

This study aimed to determine the effect of seed priming (on-farm, hydro, halo, osmo, vitamin c priming, and hardening) on the germination and seedling growth of spring rice varieties: hardinath-3, hardinath-1, and chaite-5 at ambient room temperature. A factorial completely randomized design (CRD) was carried out with two factors: methods of priming and varieties at agriculture knowledge center (AKC), kapilbastu during march 2020. There were, in total, 21 treatment combinations and four replications. Parameters observed were germination percentage, speed of germination, vigor index, root length, shoot length, fresh weight, and dry weight of rice seedlings. Hardinath-3 had superior performance in terms of germination percentage (95.35 %), vigor index (183.86), root length (11.51 cm) and shoot length (7.39 cm) compared to hardinath-1 and chaite-5; the speed of germination, however, was greater in hardinath-1. Seed hardening - alternate soaking (tap water for 24 hours) and drying - induced higher germination percentage (94.91 %), speed of germination (96.00), and vigor index (197.43) than did other priming methods; germination percentage of vitamin c primed seeds (94.75 %), nevertheless, were at statistical par with hardened seeds. Hardened hardinath-3 seeds were better in regards to germination percentage (97.50 %) and root length (12.92 cm), while the speed of germination (97.50) and vigor index (210.50) was greater in hardened hardinath-1. Vitamin c primed seeds of hardinath-3 and hardinath-1 were finer with dry weight, shoot length, and vigor index. In conclusion, farmers' are suggested to hardened seeds of hardinath-3 before sowing to promote uniform germination and growth.

Twenty three rice ( Oryza sativa L. ) varieties cultivated in Jaffna district of Sri Lanka were screened for salt tolerance at the germination and early seedling stage using different salinity levels (0, 4, 8, 12, 24 and 45 dSm -1 ). Cluster analysis was done for germination energy, speed of germination, final germination percentage, root length, root dry weight, plumule length and plumule dry weight. All the tested variables, except sodium concentration in grains, decreased with increased salt levels and had significant differences (p -1 . The osmotic effect and toxic effect due to sodium, in combination, played a major role in germination of seeds and early seedling growth due to inhibitory effect in absorption of water. Among the cultivated rice varieties in Jaffna, Pachchaperumal, At 362, Bg 250, Bg 352, H4, Bg 304, Bg 360 and CO 10 have higher germination energy, speed of germination, final germination percentage, average root length, plumule length and low sodium concentration in grains and were categorized into high tolerant group. The rice varieties At 353 and Addakari were in the tolerant group. Varieties Morungan, Periavellai, At 308 and Moddaikarupan were grouped under the salt sensitive group whereas varieties At 402 and At 303 were in highly sensitive group to salt at 24 dSm -1 during their germination stage. Tropical Agricultural Research Vol. 25 (3): 358-375 (2014)

Salinity is one of the significant problems in rice production as it limits its growth and development. Salinity can occur through natural processes due to weathering and human intervention, such as irrigation. The present study reports two different rice varieties, 'Makrilha' and 'Thevur' which are categorized as very long (< 7.50 mm) and slender in shape (< 3.0 mm) and subjected to different salt treatments (0 mM, 100 mM, 200 mM, and 300 mM NaCl solutions) and their germination responses, such as germination percentage (GP), germination index (GI), mean germination time (MGT), vigor index (VI), root and shoot length. The study concluded that Makrilha has a higher GP (88.33%) as compared to Thevur (63%) at 200 mM NaCl solution. Both the rice showed 100% germination in the control 0 mM and 100 mM salt solutions, and no germination was recorded in the 300 mM NaCl solution. GI was recorded at its maximum in Makrilha as compared to Thevur. MGT and VI were more concentrated in Thevur than Makrilha. There was a significant difference in GI, VI, root, and shoot length (P < 0.05) as salinity increased for both rices. There was no significant difference in GP (P = 0.122) and MGT (P = 0.088). The study also found a positive correlation between GI and GP. MGT is negatively correlated with GP and GI. VI is positively correlated with GP, and GI is negatively correlated with MGT. Root and shoot length are positively correlated with GP, GI, and VI but negatively correlated with MGT for both rice varieties. The rice root and shoot length are affected as salt concentration increases and are statistically significant (root P = 0.012, shoot P = 0.001). Salt is used to control weeds in almost every part of Nagaland. Thus, the effect of salt applications needs to be studied in rice. Based on the data obtained for germination parameters such as GP, GI, VI, MGT, root and shoot length, 'Makrilha' tends to show more tolerance towards salinity as compared to 'Thevur' under controlled environmental conditions. Thus, this study can provide insight into selecting rice with a higher salt tolerance for cultivation.

This study was carried out to determine the effects of different salt concentrations on germination and seedling growth of sweet sorghum [Sorghum bicolor var. saccharatum (L.) Mohlenbr.] cultivars. The research was carried out under laboratory conditions and sweet sorghum cultivars Ulusoy, Sorge, Biomarlı, Erdurmuş, and Gülşeker were used as plant material. Five different sweet sorghum cultivars and four different salt (NaCl) concentrations (0-, 100-, 200-, and 300 mM) were the subjects of the laboratory experiments which was set up in randomized plots in a factorial design with 4 replications. In the study, germination parameters such as germination percentage (GP), mean germination time (MGT), germination index (GI), coefficient of uniformity of germination (CUG) and germination speed (GS), and seedling growth parameters such as root and shoot fresh weight, root and shoot dry weight, root and shoot length, lateral root number and lateral root length were investigated. As a result of the research, it was determined that the germination and seedling growth parameters (excluding MGT) decreased as salt concentration increased. This decrease in germination characteristics was significant at 100 mM salt dose according to the average values of the cultivars, and it was observed that the cultivars were more sensitive to salt stress in the seedling development stage than the germination stage. In the study, it was determined that there were significant differences between sweet sorghum genotypes under salt-stressed conditions during germination and seedling stages. In this sense, Ulusoy and Erdurmuş sweet sorghum cultivars were prominent in terms of salt tolerance. It is important to use salt tolerant cultivars considering the genotypic differences in sweet sorghum cultivation in salt-affected areas.

Drought is a serious bottleneck in the production of rice globally. For this, an experiment was conducted in-vitro on six rice genotypes viz. BRRI Dhan-28, Begunbahar, Burikatari, Pashpai, Dular and Begunbichi to investigate the effect polyethylene glycol (PEG) mediated artificial drought on morpho-physiological parameters such as germination percentage, shoot length, root length, fresh weight, dry weight, turgid weight, relative water content and proline accumulation. Here, different doses of PEG-6000 viz. 0gL-1, 15gL-1, 30gL-1, 45gL-1 and 60gL-1 were used with Murashige and Skoog (MS) medium. The results demonstrated that BRRI Dhan-28, Burikatari and Dular revealed greater performance at control conditions but at the highest degree of water stress conditions only Burikatari showed higher mean value for all parameters studied. Again, Begunbichi followed by BRRI Dhan-28 exhibited the lowest mean value for almost all traits except for proline accumulation. Here, water stress decreased the performance of morpho-physiological characters except proline accumulation in rice. The cluster analysis was performed and distributed into three groups where there was a significant variation among the clusters at different water stress conditions. Here, the genotype Burikatari is more diverse giving maximum Euclidian distances in drought treatments. It could be considered as a parent in the hybridization program against Begunbahar, Dular and Paspai. Therefore, considering the mean performances and cluster analysis, Burikatari exhibited greater performances against the highest degree of drought conditions. This genotype may bear drought-tolerant gene for which could be utilized for further development of drought-tolerant variety and gene transfer.