In vitro screening of rice landraces for increased drought tolerance at early growth stages using Polyethylene glycol (PEG 6000)

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.

In order to study the plant growth regulator, using salicylic acid (SA) on germination and growth indices for laboratory research in crop year 2014-2015, which was conducted at the research center Safiabad-Dezful, Khuzestan province. The treatments included four levels of priming with salicylic acid {control (distilled water), 0.7, 1.2, 1.7 mM} in a completely randomized design in three replications. The results showed that the control treatment reduced the decrease in germination time. The highest percentage of germination and related characteristics of the control (distilled water) was obtained. Seed vigor and seedling vigor index were reduced in high concentrations of salicylic acid. The germination percentage of an average daily germination, seed vigor and seedling vigor index had a positive and significant correlation with the daily germination rate showed a significant negative correlation. The results of comparison of treatments showed that the treatment concentration of 0.7 mM salicylic acid highest (22.3 days) and control (distilled water) lowest (0.3 day) had mean germination time. Effects of priming showed the highest mean daily germination (15.44) related to the control and the lowest (2.97) related to the concentration of 7.1 mM salicylic acid. Also, the results showed that the 1.7 mM salicylic acid treatment had the highest number of germinated seeds per day (0.3880) and control treatment had the least number of germinated seeds per day (0.6467). The highest vigor index was observed in control treatment with seedling length of (8.15 cm) and the lowest vigor index was observed in 1.7 mM salicylic acid treatment with seedling length of (1.54 cm). The highest seedling vigor index was observed in control treatment (33.58) and the lowest seedling vigor index was observed in 1.7 mM salicylic acid treatment (17.20). The coefficient velocity germination rate in control treatment was highest (3) and in the 1.7 mM salicylic acid treatment was lowest (0.15). The correlation coefficient between vigor index and seedling vigor index has the highest value (98%). There was a positive correlation between germination percentage and mean daily germination and there was a negative correlation between germination percentage and daily germination speed.

نیاز به گراس‌های متحمل به شوری در حال افزایش است. رشد سریع جمعیت شهر نشین فشار عمدهای را به منابع آب شیرین وارد ساخته است. به همین منظور جهت بررسی تاثیر تنش شوری بر جوانه‌زنی و رشد گیاهچه توده‌های مختلف فسکویه بلند (Festuca arundinacea) آزمایشی به صورت فاکتوریل در قالب طرح کاملا تصادفی با 12 ژنوتیپ فسکویه بلند از مناطق اصفهان (یزد آباد)، کامیاران، یاسوج، داران، سناجان، بروجن، مشهد، سمیرم، گندمان (نصیرآباد)، سنندج و البرز و فسکویه بلند وارداتی به عنوان فاکتور اول و چهار سطح شوری 0، 45، 90 و 135 میلی‌مولار Nacl به عنوان فاکتور دوم با چهار تکرار انجام شد. نتایج نشان داد که افزایش سطوح شوری موجب کاهش معنی‌دار درصد جوانه‌زنی، سرعت جوانه‌زنی، طول ریشهچه، طول ساقهچه وشاخصبنیه بذر در تمام ژنوتیپ ها شد. همچنین، اثر متقابل شوریو ژنوتیپ نیز برای صفات سرعت و درصد جوانه زنی و بنیه بذر معنی‌دار بود.اکثر گراس‌های مورد مطالعه در این آزمایش شوری تا 45 میلی‌مولار را بدون آن‌که مولفه‌های جوانه‌زنی به طور قابل ملاحظه‌ای تحت تاثیر قرار بگیرند را تحمل نمودند. توده‌های مشهد و بروجن در سطح شوری 135 میلی‌مولار بیشترین میزان را در صفات درصد و سرعت جوانه‌زنی نشان دادند. همچنین، در مجموع صفات جوانه‌زنی، توده‌های داران و مشهد نسبت به سایرین کمترین کاهش را داشته و می‌توانند به عنوان ژنوتیپ‌های متحمل به شوری در مرحله جوانه‌زنی پیشنهاد گردند.

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.

The effect of numerous heavy metals such as Co (as CoCl 2 ), Cu (as CuSO 4 ), Zn (as ZnSO 4 ) and As (as Na 2 HAsO 4 ) concentrations on garden cress (L. sativum L.) was tested. During this experiment, the measurement of several parameters such as root length (RL), plumule length (PL), germination percentage (GP), germination index (GI), germination rate index (GRI), vigor index (VI), coefficient of velocity of germination (CVG) and mean germination time (MGT) were done. The results confirmed that various treatments of heavy metals possessed statistically significant impacts on the GRI, GI, MGT, CVG and VI. However, at different metal concentrations indicated that GP did not differ significantly for Co, Cu and Zn and differ significantly for As denoting an inverted threshold dose-response model. The results showed that the trend of GI, VI, CVG of As, RL and PL of As and Cu reduced with increasing metal doses indicating an inverted threshold model. The GRI decreased with mounting metal concentrations implying an inverted U-shaped germination curve of L. sativum L. seeds in the experiment, and the same for PL of Co and Zn. However, the results of MGT and CVG (of Co, Cu and Zn) denote no hermetic effect. In addition, the results indicated that root length was decreased more than shoot length and was expressed as the sensitivity index. Generally, it concluded that the toxicity of the examined metals diminishes by the following succession: As > Cu > Co > Zn.

The study aimed to determine the effects of drought (0.0, -2.0, -4.0, and -6.0 bar PEG 6000) and low temperature (18°C) on the germination and early seedling growth of three melon cultivars (Kırkağaç 589, Hasanbey 1, and Toros Sarıbal). Germination percentage, mean germination time, germination index, root length, shoot length, fresh and dry weight of the seedling, and vigor index of the melon cultivars were investigated. The results showed significant effects of low temperature and drought stress on the germination and seedling growth of melon cultivars. As temperature decreased and drought increased, the germination percentage decreased, and mean germination time was delayed. Drought stress led to a decrease in germination percentage, index, and all investigated seedling growth parameters, while the response of melon cultivars to drought stress varied. Seedling growth was more affected by low temperature than germination. Low temperature decreased germination percentage from 87.2% to 63.7% and seedling fresh weight from 140 mg/plant to 64 mg/plant. Each increase in drought levels resulted in a decrease in germination and seedling growth parameters of melon cultivars. Any seedling growth was not observed in Hasanbey 1 and Toros Sarıbal at -6.0 bar at 18°C. Melon cultivars showed different levels of tolerance to drought stress during germination and seedling growth stages, while they could maintain it up to -4.0 bar. It was concluded that Kırkağaç 589 germinated and grew better under drought stress at both optimum and low temperatures.

In order to study the response of some Chickpea (Cicer arietinum L.) cultivars i.e. Giza 1, Giza 2, Giza 3, Giza 3, Giza 4, Giza 195, Giza 531, and Chickpea stand1to germination under salinity concentrations i.e. control treatment, 4, 8, 12, 16, and 20 dSm-1 NaCl and to confirm the seedling growth performance. A laboratory experiment was laid out at Giza Central Seed Testing Laboratory of Central Administration for Seed Certification, Ministry of Agriculture, Egypt. Giza 3 cultivar exceeded other cultivars in germination percentage, germination index, seedling vigor index, shoot length, shoot and root dry weight followed by Giza 1 and Giza 2 cultivars. Giza 2 cultivar recorded highest mean germination time, followed by chickpea stand 1 and Giza 4 cultivars. Giza 195 cultivar exceeded other cultivars in root length and Giza 531 and Giza 1 cultivars surpassed other cultivars in shoot fresh weight. Chickpea stand 1 and Giza 195 cultivars surpassed other cultivars in seedling height reduction and Giza 1, Giza 2, Giza 3, and Giza 4, came in the second rank. However, the lowest percentages of seedling height reduction were obtained from Giza 531 cultivar. Increasing salinity levels from 0 to 20 dSm-1 significantly decreased germination percentage, germination index, seedling vigor index, shoot and root length, shoot and root fresh weight, shoot and root dry weight and relative dry weight. The control treatment recorded highest averages of these characters, vice versa mean germination time and seedling height reduction. Germination index, seedling vigor index, shoot and root length (cm), shoot and root fresh weight (mg), shoot and root dry weight (mg), seedling height reduction % and relative dry weight % significantly affected by the interaction between chickpea cultivars and salinity concentration. Giza 3, Giza 1 and Giza 2 cultivars were more tolerant to salinity and recommended to be used in breeding program for enhancing chickpea cultivation in newly reclaimed soils.

Drought stress is one of the most important environmental factors in reduction of growth, development and production of plants. Germination is one of the main growth stages and success in this stage is dependent on moisture content of soil at time of planting. This study examined germination characteristics of seven corn hybrids under five levels of osmotic potential (0, -3, -6, -9 and -12 bar) by polyethylene glycol (PEG) 6000 using a factorial experiment based on a completely randomized design with three replications. Results indicated that water potential significantly reduced germination percent (71.2%), germination rate (24.2%), root length (60%), shoot length (89.8%), seedling length (71.2%) and seed vigour (91.7%). The mean germination time and root/shoot length ratio increased with decrease in the osmotic potential of PEG solution. Hybrid K3651/1×K166B produced the highest germination percent, germination rate, root length, seedling length and seed vigour, hence this hybrid was the most tolerant hybrid to drought stress. Key words: Corn, drought stress, early growth, germination, PEG.

Drought is a key stress factor that limits rice production globally. The present study was carried out to identify drought tolerant rice lines at the germination and seedling stages using polyethylene glycol (PEG) induced stress. Twenty promising high yielding BC2F4 lines, stacked with drought yield QTLs qDTY₁⸳₁ and qDTY₁₂.₁, derived from the cross between Manu Ratna X Improved White Ponni, were subjected to drought stress. Drought was imposed during germination using three levels (0, 10 and 15%) of polyethylene glycol (PEG 6000) concentrations. The experiment was conducted in factorial completely randomized block design with three replications and the observations on number of seeds germinated, root length, shoot length, germination index, germination stress tolerance index, fresh weight stress tolerance index, dry weight stress tolerance index and seedling vigour index were evaluated after stress treatment. A significant difference was noted among lines for characters under drought stress. Among the lines, MIB-29-2-3-1, MIB-29-8-5-35, MIB-43-5-3-66 and MIB-119-5-7-33 were selected which showed higher germination percentage, root length, shoot length, germination stress tolerance index and and seeding vigour index. The selected lines can be further evaluated in the field to develop drought tolerant rice varieties.

This study aimed to explore the response of pumpkin to salt and drought stress during germination and early plant growth stages. Salt stress was induced with various sodium chloride concentrations (0.00%, 0.25%, 0.50%, and 0.75%) in non-drought (distilled water) and drought (15% PEG-6000) conditions. The seeds of the pumpkin cultivar T28 for snacks were germinated between filter papers using the respective solutions. In the pot experiment, the seedlings at the 2-leaf stage were exposed to these stresses for 30 days. The plant height, fresh weight, dry weight, leaf area, leaf dry matter, chlorophyll content (Chl), relative water content (RWC), and cell membrane stability (CMS) of the plants were inquired. Drought markedly reduced the germination index, plant height, fresh weight, dry weight, leaf area, RWC, and CMS. Conversely, increased mean germination time, Chl, and dry matter were determined in drought conditions. Salinity stress above 0.50% NaCl influenced these traits, with salinity’s inhibitory effects surpassing those of drought. Germination percentage dropped from 100% to 46% at 0.75% NaCl under drought, whereas it remained stable under non-drought stress. Pumpkin was more sensitive to drought and salinity stress at the germination stage than at the early growth stage. The correlation between germination and seedling growth parameters indicated that the germination index and mean germination time were substantially associated with nearly all growth traits of pumpkin. The study highlights the germination index as a key indicator of stress tolerance and identifies 0.50% NaCl as a critical threshold level for pumpkin under salt and drought stress.

Successful establishment of plants largely depends on successful germination. This study examined the effects of different methods of seed priming on germination percentage, germination index, time of 50 per cent emergence, mean germination time, root and shoot length, dry weight of seedling and vigour index of maize. The experiment was conducted in the laboratory of Department of Agronomy, Indira Gandhi Krishi Vishwavidyalaya, Raipur (Chhattisgarh) during 2013-14 using Completely Randomized Design with three replications. All growth and developmental parameters of maize seed were positively responded with seed priming in comparison to unprimed treatment. Bio-priming of maize seed for 24 hours showed the highest positive effect on all the parameters and recorded significantly highest values of germination percentage (93.11), germination index (29.84), root length (22.73 cm), shootlength(19.67), seedling dry weight (1.56 g) as well as seedling vigour index (3947.49). The level of T 50 (1.51 days) and MGT (2.14 days) were the lowest due to bio-priming for 24 hours in comparison to other priming treatments.

Germination is an important phenomenon in plant life cycle. It is an irreversible process. Germination studies give an idea about seed's performance. This study can be used to enhance the harvest of plants. Brasica juncea is an important oilseed crop. It is used as oil source and has medicinal values. In the present investigation, different germination parameters such as percentage germination (GP), speed of germination (SOG), coefficient of germination (COG), germination rate (GR), mean germination time (MGT) and germination index (GI) were studied. Also, some seedling growth parameters such as shoot and root lengths (SL and RL), vigor index (VI), seed stamina index (SSI) and seedling growth (SG) were also recorded in 15 varieties of B. juncea. Results show that varieties exhibited different levels of germination percentage ranging from 43.33% to 96.66%. It was observed that SOG was maximum in varieties 12 (Navgold) and was lowest in variety 5(RGN-229). COG was maximum in variety 12(Navgold), whereas in variety 9(RH-30) it was minimum. Interestingly, the highest MGT was recorded lowest in variety 5(RH-30) and highest was observed in variety 12(Navgold). Significant differences were observed between shoot and root lengths in different varieties. The maximum root length was observed maximum in variety 6(RGN-236), while the minimum was measured in variety 12(Navgold). Variety 7 (Maya) showed the maximum shoot length whereas variety 6(RGN-236) showed minimum. The vigor index was found to be maximum in variety 8 (PCR-7) and minimum in variety 2 (RGN-48).

The objective of the study was to determine the effects of boron concentrations on germination and seedling growth of winter canola varieties under laboratory conditions. Seeds of four winter canola varieties (KWS Cyrill CL, Miranda, PT264, and NK Caravel) were germinated between papers with different boron levels (0, 20, 40, 60, 80, and 100 mg B L-1) consisting of sodium borate (Na2B8O13.4H2O) at 20°C for 7 days. The germination percentage, mean germination time, germination index, seedling growth parameters, and dry matter were measured. The results showed that germination percentage, mean germination time, and germination index were negatively affected by increasing B concentrations. When B levels increased, root and shoot lengths and weights were also inhibited, while the responses of canola varieties differed. B levels had a significant effect on shoot length, which decreased from 5.15 cm to 1.82 cm and root length from 4.99 cm to 2.59 cm. Under boron stress, KWS Cyrill CL germinated higher and developed longer roots and shoots. Differences in both germination and seedling growth among canola cultivars were observed at 80 mg B L-1 and higher. It was concluded that there was a genotypic variation among canola varieties concerning boron toxicity and that KWS Cyrill CL was more tolerant to high boron concentrations than the other varieties.

Abstract: Seed germination and early seedling growth are sensitive to drought stress in wheat. A factorial experiment was arranged based on a completely randomized design with three replicates to study the impacts of TiO2 nanoparticles (TiO2 NPs: 0, 500, 1000 and 2000 mg.L) and sodium nitroprusside (SNP: 0 and 100 μM), as NO donor, on seed germination and seedling growth of wheat under polyethylene glycol (PEG)-induced drought stress (0, -0.4 and -0.8 MPa). Our results revealed that PEG-stimulated drought stress significantly decreased germination percentage (GP), germination energy (GE), germination rate (GR), root length (RL), shoot length (SL), root fresh weight (RFW), shoot fresh weight (SFW) and vigor index (VI) but increased mean germination time (MGT) in wheat seeds. However, application of TiO2 NPs and SNP alone or in combination significantly enhanced GP, GE, GR, RL, SL, RFW, SFW and VI up to 23.72%, 50%, 33.74%, 85.38%, 93.28%, 73%, 91.91% and 91.04% respectively, but significantly reduced MGT up to 28.36% under severe drought stress. Our results showed that application of TiO2 NPs and SNP alone or in combination can significantly alleviate the adverse effects of PEG-stimulated drought stress on seed germination and early seedling growth of wheat.

Quality of seeds of three cultivars (IPSA Seem-2, BU Seem-3 and IPSA Seem-5) of lablab bean (Lablab purpureus L. Sweet) collected from crops planted in three different dates (15 May, 15 July, and 15 September 2003) was assessed in respect of different parameters. The maximum percentage of seeds of cv. IPSA Seem-2 was germinated (95.67) whereas, BU Seem-3 had the maximum electrical conductivity (EC) (316.06 μs/cm) followed by IPSA Seem-5 (261.53 μs/cm). The cv. IPSA Seem-2 also had the highest vigour index (VI) (65.04) and coefficient of germination (CG) (58.90). The maximum length of root and shoot was 13.73 cm and 12.98 cm in IPSA Seem-5 and IPSA Seem-2, respectively. The percentage of dry matter of root and shoot was the highest for BU Seem-3 (23.68 and 12.15, respectively), whereas, the composite sample of root and shoot of IPSA Seem-2 had the highest value of dry matter (14.54%). Seeds of September planted crops had better germination percentage (95.67), VI (50.07), CG (47.65), length of root (13.63 cm), dry matter of root (24.79%), shoot (13.34%) and composite sample (15.14%). Whereas, seeds of May planted crops had the maximum EC (388.23 μs/cm) and length of shoot (15.29 cm). Seeds of cv. IPSA Seem-2 collected from September planted crops had the maximum germination percentage (97.75), VI (70.96), CG (64.13), length of shoot (11.41 cm) and dry matter percentage of composite sample of root and shoot (16.58). BU Seem-3 of May planted crops had the maximum EC (469.78 μs/cm). But BU Seem-3 of September planting had the highest dry matter of root of seedling (25.19%). Seedlings of cv. IPSA Seem-5 planted in September had the highest length of roots (14.63 cm) and dry matter of shoot (13.79%). Key Words: Seed quality, photo-insensitive, dates of planting and lablab bean. doi:10.3329/bjar.v33i3.1597 Bangladesh J. Agril. Res. 33(3) : 381-389, September 2008