Drought regimes can be characterized by the variability in the quantity of rainfall and the duration of rainless periods. However, most research on plant response to drought has ignored the impacts of rainfall variation, especially with regard to the influence of nonstructural carbohydrates (NSCs) in promoting drought resistance. To test the hypothesis that these components of drought differentially affect NSC dynamics and seedling resistance, we tracked NSC in plant tissues of tropical tree seedlings in response to manipulations of the volume and frequency of water applied. NSC concentrations decreased in woody tissues under infrequent-high watering but increased under no watering. A faster decline of growth relative to stomatal conductance in the no watering treatment was consistent with NSC accumulation as a result of an uncoupling of growth and photosynthesis, while usage of stored NSCs in woody tissues to maintain function may account for the NSC decline under infrequent-high watering. NSCs, and specifically stem NSCs, contributed to drought resistance under severe water deficits, while NSCs had a less clear role in drought resistance to variability in water availability. The contrasting response of NSCs to water variability and deficit indicates that unique processes support seedling resistance to these components of drought.
Occasional periods of drought are typical of most tropical forests, but climate change is increasing drought frequency and intensity in many areas across the globe, threatening the structure and function of these ecosystems. The effects of intermittent drought on tropical tree communities remain poorly understood and the potential impacts of intensified drought under future climatic conditions are even less well known. The response of forests to altered precipitation will be determined by the tolerances of different species to reduced water availability and the interactions among plants that alleviate or exacerbate the effects of drought. Here, we report the response of experimental monocultures and mixtures of tropical trees to simulated drought, which reveals a fundamental shift in the nature of interactions among species. Weaker competition for water in diverse communities allowed seedlings to maintain growth under drought while more intense competition among conspecifics inhibited growth under the same conditions. These results show that reduced competition for water among species in mixtures mediates community resistance to drought. The delayed onset of competition for water among species in more diverse neighbourhoods during drought has potential implications for the coexistence of species in tropical forests and the resilience of these systems to climate change.
RNA-binding proteins (RBPs) have been implicated as regulatory proteins involved in the post-transcriptional processes of gene expression in plants under various stress conditions. In this study, we report the cloning and characterization of a gene, designated as EgRBP42, encoding a member of the plant heterogeneous nuclear ribonucleoprotein (hnRNP)-like RBP family from oil palm (Elaeis guineensis Jacq.). EgRBP42 consists of two N-terminal RNA recognition motifs and a glycine-rich domain at the C-terminus. The upstream region of EgRBP42 has multiple light-responsive, stress-responsive regulatory elements and regulatory elements associated with flower development. Real-time RT-PCR analysis of EgRBP42 showed that EgRBP42 was expressed in oil palm tissues tested, including leaf, shoot apical meristem, root, female inflorescence, male inflorescence and mesocarp with the lowest transcript level in the roots. EgRBP42 protein interacted with transcripts associated with transcription, translation and stress responses using pull-down assay and electrophoretic mobility shift assay. The accumulation of EgRBP42 and its interacting transcripts were induced by abiotic stresses, including salinity, drought, submergence, cold and heat stresses in leaf discs. Collectively, the data suggested that EgRBP42 is a RBP, which responds to various abiotic stresses and could be advantageous for oil palm under stress conditions. Key message EgRBP42 may be involved in the post-transcriptional regulation of stress-related genes important for plant stress response and adaptation.
Non-invasive measures of stress are crucial for captive and conservation management programs. The adrenal hormone dehydroepiandrosterone-sulfate (DHEAS) has recently been adopted as a stress marker, but there is little investigation of its relationship to glucocorticoids (GC), well-known indicators of stress. This study examined the influence of age, reproductive state and environment on GC and DHEAS levels in orangutans, to test whether the GC/DHEAS ratio can provide an index of stress response in primates. We measured fecal GC (fGC) and fecal DHEAS (fDHEAS) concentrations in 7 captive orangutans from zoological parks in Japan and 22 wild orangutans from Danum Valley Conservation Area, Malaysia. We found that in a stressful condition (transportation), fDHEAS levels increased 2 days after the fGC response, which occurred 1 day after the stressor. One pregnant female had elevated levels of both hormones, and a higher fGC/fDHEAS ratio than baseline. Females in the first year of lactation had fGC levels and the fGC/fDHEAS ratio significantly higher than both baseline and females in the second and subsequent years of lactation. There was no effect of age on fGC levels, but the fGC/fDHEAS ratio was higher in infants than adults and adolescents. fDHEAS concentrations were lower in infants than juveniles, adolescents and adults, a phenomenon known as adrenarche, shared with humans and other great apes. We suggest that changes in DHEAS during orangutan life history are associated with changes in the dynamics of maintaining homeostasis that vary with age and reproductive state. The GC/DHEAS ratio index is useful to evaluate age-related abilities of responding to stressful challenges.
The small genome size of rice relative to wheat and barley, together with its salt sensitivity, make it an ideal candidate for studies of salt stress response. Transcriptomics has emerged as a powerful technique to study salinity responses in many crop species. By identifying a large number of differentially expressed genes (DEGs) simultaneously after the stress induction, it can provide crucial insight into the immediate responses towards the stressor. In this study, a Malaysian salt-tolerant indigenous rice variety named Bajong and one commercial rice variety named MR219 were investigated for their performance in plant growth and ion accumulation properties after salt stress treatment. Bajong was further investigated for the changes in leaf's transcriptome after 6 h of stress treatment using 100 mM NaCl. Based on the results obtained, Bajong is found to be significantly more salt tolerant than MR219, showing better growth and a lower sodium ion accumulation after the stress treatment. Additionally, Bajong was analysed by transcriptomic sequencing, generating a total of 130 millions reads. The reads were assembled into de novo transcriptome and each transcript was annotated using several pre-existing databases. The transcriptomes of control and salt-stressed samples were then compared, leading to the discovery of 4096 DEGs. Based on the functional annotation results obtained, the enrichment factor of each functional group in DEGs was calculated in relation to the total reads obtained. It was found that the group with the highest gene modulation was involved in the secondary metabolite biosynthesis of plants, with approximately 2.5% increase in relation to the total reads obtained. This suggests an extensive transcriptional reprogramming of the secondary metabolic pathways after stress induction, which could be directly responsible for the salt tolerance capability of Bajong.
The use of periodical water stress and potassium fertilization may enhance rice tolerance to drought stress and improve the crop's instantaneous water use efficiency without much yield reduction. This study was conducted to assess the effects of different periodical water stress combined with potassium fertilization regimes on growth, yield, leaf gas exchanges and biochemical changes in rice grown in pots and compare them with standard local rice grower practices. Five treatments including (1) standard local grower's practice (control, 80CF = 80 kg K2O/ha + control flooding); (2) 120PW15 = 120 kg K2O/ha + periodical water stress for 15 days; (3) 120DS15V = 120 kg K2O/ha + drought stress for 15 days during the vegetative stage; (4) 120DS25V = 120 kg K2O/ha + drought stress for 25 days and (5) 120DS15R = 120 kg K2O/ha + drought stress for 15 days during the reproductive stage, were evaluated in this experiment. Control and 120PW15 treatments were stopped at 100 DAS, and continuously saturated conditions were applied until harvest. It was found that rice under 120PW15 treatment showed tolerance to drought stress evidenced by increased water use efficiency, peroxidase (POX), catalase (CAT) and proline levels, maximum efficiency of photosystem II (fv/fm) and lower minimal fluorescence (fo), compared to other treatments. Path coefficient analysis revealed that most of parameters contribute directly rather than indirectly to rice yield. In this experiment, there were four factors that are directly involved with rice yield: grain soluble sugar, photosynthesis, water use efficiency and total chlorophyll content. The residual factors affecting rice yield are observed to be quite low in the experiment (0.350), confirming that rice yield was mostly influenced by the parameters measured during the study.
Silicon (Si) plays an important role in reducing plant susceptibility against a variety of different biotic and abiotic stresses; and also has an important regulatory role in soil to avoid heavy metal toxicity and providing suitable growing conditions for plants. A full-length cDNAs of 696bp of serine-rich protein was cloned from mangrove plant (Rhizophora apiculata) by amplification of cDNA ends from an expressed sequence tag homologous to groundnut (Arachis hypogaea), submitted to NCBI (KF211374). This serine-rich protein gene encodes a deduced protein of 223 amino acids. The transcript titre of the serine-rich protein was found to be strongly enriched in roots compared with the leaves of two month old mangrove plants and expression level of this serine-rich protein was found to be strongly induced when the mangrove seedlings were exposed to SiO2. Expression of the serine-rich protein transgenic was detected in transgenic Arabidopsis thaliana, where the amount of serine increased from 1.02 to 37.8mg/g. The same trend was also seen in Si content in the roots (14.3%) and leaves (7.4%) of the transgenic A. thaliana compared to the wild-type plants under Si treatment. The biological results demonstrated that the accumulation of the serine amino acid in the vegetative tissues of the transgenic plants enhanced their ability to absorb and accumulate more Si in the roots and leaves and suggests that the serine-rich protein gene has potential for use in genetic engineering of different stress tolerance characteristics.
Silicon (Si) is the second most abundant element in soil after oxygen. It is not an essential element for plant growth and formation but plays an important role in increasing plant tolerance towards different kinds of abiotic and biotic stresses. The molecular mechanism of Si absorption and accumulation may differ between plants, such as monocotyledons and dicotyledons. Silicon absorption and accumulation in mangrove plants are affected indirectly by some proteins rich in serine and proline amino acids. The expression level of the genes responsible for Si absorption varies in different parts of plants. In this study, Si is mainly observed in the epidermal roots' cell walls of mangrove plants compared to other parts. The present work was carried out to discover further information on Si stress responsive genes in Rhizophora apiculata, using the suppression subtractive hybridization technique. To construct the cDNA library, two-month-old seedlings were exposed to 0.5, 1, and 1.5 mM SiO2 for 15 hrs and for 1 to 6 days resulting in a total of 360 high quality ESTs gained. Further examination by RT-PCR and real-time qRT-PCR showed the expression of a candidate gene of serine-rich protein.
The use of nanominerals, such as nano-zinc, represents a promising and emerging technology in the animal farming industry. Due to the small particle size and bioavailability of nano-zinc, it can be easily assimilated in the digestive system, thereby reducing excretion and environmental pollution. The present study was conducted to assess the effects of zinc oxide nanoparticles (ZnONPs) on the growth performance, zinc (Zn) concentration in edible tissues, thiobarbituric acid reactive substance, and corticosterone concentrations in broilers reared under normal or heat stress environmental conditions. The experiment was performed with a completely randomized design based on a 4 × 2 factorial arrangement consisting of 4 diets (basal diet + 60 mg/kg conventional zinc oxide as control diet; basal diet + 40 mg/kg of ZnONPs; basal diet + 60 mg/kg of ZnONPs; and basal diet + 100 mg/kg of ZnONPs) and 2 environmental conditions (normal and heat stress). On day 22, birds from each dietary group were divided equally to normal temperature (23 ± 1°C throughout) or heat stress conditions (34 ± 1°C daily for 6 h from 10:00 am until 4:00 pm). From 1 to 42 D of age, the broiler chickens fed 100 mg/kg ZnONPs exhibited lower feed intake and feed conversion ratio than the control. The accumulation of Zn in the liver of broilers was significantly higher among all treatment groups compared to breast and thigh muscle tissues regardless of the temperature conditions. At 40 and 60 mg/kg ZnONPs, the malondialdehyde content increased in thigh muscle of broilers at 7 D postmortem, indicating that ZnONPs potentially inhibited the antioxidant system in muscle tissues. The control and ZnONPs at 40 mg/kg and 60 mg/kg led to low serum corticosterone levels that may be attributed to the antioxidant and antistress properties of Zn. Taken together, although supplementation with ZnONPs at 40 mg/kg and 60 mg/kg alleviated the negative results of heat stress, further research is needed to determine the optimal level of dietary ZnONPs supplementation.
This study was conducted to investigate the median lethal concentration (LC50) of copper pyrithione (CuPT) at 96-hr exposure on adult Javanese medaka (Oryzias javanicus) in revealing toxicological effects of CuPT contamination in the tropical area. Wild stock fishes were acclimatized for 14-days prior analysis. Triplicate of test tanks for seven test concentrations were placed with ten fishes each, this includes two control tanks. The behaviour of the tested fishes was manually observed through a camera. The LC50 of CuPT at 96-h was found to be 16.58mg/L. Tested fishes swam slowly in vertical movement and swam fast towards food during feeding time as the sign of stress behaviour. Meanwhile, fishes in the two control groups swam actively in a horizontal manner and no excitement during feeding time. No mortality in control groups. Results indicate CuPT to be toxic to Javanese medaka at low concentration and caused behavioural stress.
Recent achievements in plant microRNA (miRNA), a large class of small and non-coding RNAs, are very exciting. A wide array of techniques involving forward genetic, molecular cloning, bioinformatic analysis, and the latest technology, deep sequencing have greatly advanced miRNA discovery. A tiny miRNA sequence has the ability to target single/multiple mRNA targets. Most of the miRNA targets are transcription factors (TFs) which have paramount importance in regulating the plant growth and development. Various families of TFs, which have regulated a range of regulatory networks, may assist plants to grow under normal and stress environmental conditions. This present review focuses on the regulatory relationships between miRNAs and different families of TFs like; NF-Y, MYB, AP2, TCP, WRKY, NAC, GRF, and SPL. For instance NF-Y play important role during drought tolerance and flower development, MYB are involved in signal transduction and biosynthesis of secondary metabolites, AP2 regulate the floral development and nodule formation, TCP direct leaf development and growth hormones signaling. WRKY have known roles in multiple stress tolerances, NAC regulate lateral root formation, GRF are involved in root growth, flower, and seed development, and SPL regulate plant transition from juvenile to adult. We also studied the relation between miRNAs and TFs by consolidating the research findings from different plant species which will help plant scientists in understanding the mechanism of action and interaction between these regulators in the plant growth and development under normal and stress environmental conditions.
The SCF complex is a widely studied multi-subunit ring E3 ubiquitin ligase that tags targeted proteins with ubiquitin for protein degradation by the ubiquitin 26S-proteasome system (UPS). The UPS is an important system that generally keeps cellular events tightly regulated by purging misfolded or damaged proteins and selectively degrading important regulatory proteins. The specificity of this post-translational regulation is controlled by F-box proteins (FBPs) via selective recognition of a protein-protein interaction motif at the C-terminal domain. Hence, FBPs are pivotal proteins in determining the plant response in multiple scenarios. It is not surprising that the FBP family is one of the largest protein families in the plant kingdom. In this review, the roles of FBPs, specifically in plants, are compiled to provide insights into their involvement in secondary metabolites, plant stresses, phytohormone signalling, plant developmental processes and miRNA biogenesis.
Plants have developed diverse physical and chemical defence mechanisms to ensure their continued growth and well-being in challenging environments. Plants also have evolved intricate molecular mechanisms to regulate their responses to biotic stress. Non-coding RNA (ncRNA) plays a crucial role in this process that affects the expression or suppression of target transcripts. While there have been numerous reviews on the role of molecules in plant biotic stress, few of them specifically focus on how plant ncRNAs enhance resistance through various mechanisms against different pathogens. In this context, we explored the role of ncRNA in exhibiting responses to biotic stress endogenously as well as cross-kingdom regulation of transcript expression. Furthermore, we address the interplay between ncRNAs, which can act as suppressors, precursors, or regulators of other ncRNAs. We also delve into the regulation of ncRNAs in response to attacks from different organisms, such as bacteria, viruses, fungi, nematodes, oomycetes, and insects. Interestingly, we observed that diverse microorganisms interact with distinct ncRNAs. This intricacy leads us to conclude that each ncRNA serves a specific function in response to individual biotic stimuli. This deeper understanding of the molecular mechanisms involving ncRNAs in response to biotic stresses enhances our knowledge and provides valuable insights for future research in the field of ncRNA, ultimately leading to improvements in plant traits.
Oxidative and nitrosative stress underlies cataractogenesis, and therefore, various antioxidants have been investigated for anticataract properties. Several vitamin E analogs have also been studied for anticataract effects due to their antioxidant properties; however, the anticataract properties of tocotrienols have not been investigated. In this study, we investigated the effects of topically applied tocotrienol on the onset and progression of cataract and lenticular oxidative and nitrosative stress in galactosemic rats.
1. This study was undertaken to examine the effect of feeding glycine (Gly)-fortified low protein (LP) diets on the growth performance, duodenal morphology and caecal microbial populations of broiler chickens raised under unheated, cyclic or constant heat stress environmental conditions. 2. From d 1 to 21 (starter phase), an equivalent number of birds were fed either a normal protein (NP) diet or a LP diet fortified with Gly. From d 22 to 42 (grower phase), an equivalent number of birds from each starter diet were distributed to one of the following dietary groups: (i) an NP diet during the starter and grower phases (NPNP), (ii) an NP diet during the starter phase and a LP diet during the grower phase (NPLP), (iii) an LP diet during the starter phase and an NP diet during the grower phase (LPNP) or (iv) LP diets during both phases (LPLP). 3. Commencing from d 22, an equivalent number of birds from each dietary group were exposed to (i) 23 ± 1°C throughout (unheated), (ii) 34 ± 1°C for 7 h each day from 10:00 to 17:00 (cyclic heat) or (iii) 34 ± 1°C throughout (constant heat). 4. Feeding the LP diet during the starter phase resulted in feed intake (FI), weight gain (WG), feed conversion ratios (FCR) and energy efficiency ratios (EER) similar to those for the NP diet. The birds fed the LP diet had a significantly higher protein efficiency ratio (PER) compared with the birds fed the NP diet. 5. During the grower phase, there were significant diet × temperature interactions for F, WG, FCR, PER, EER, villus height, crypt depth and caecal Clostridia. The birds fed the NPLP and LPLP diets had lower FI, WG and EER, higher FCR, shorter villus height and crypt depth and higher caecal Clostridia compared with the birds fed LPNP and NPNP diets under constant heat stress. However, feeding birds the NPLP and LPLP diets resulted in FI, WG, EER, FCR, morphology parameters and caecal Clostridia equivalent to the birds fed LPNP and NPNP diets, as well as improved PER, under unheated and cyclic heat stress conditions. 6. In conclusion, our results indicate that Gly-fortified LP diets can be fed to broilers under normal and acute heat stress environmental conditions without any adverse effects on performance. However, the use of such LP diets can be detrimental to broilers under chronic heat stress conditions.
The hypothalamic paraventricular nucleus (PVN) is a key integrative site for the neuroendocrine control of the circulation and of the stress response. It is also a major source of the neuropeptide hormone vasopressin (VP), and co-expresses V1a receptors (V1aR). We thus sought to investigate the role of V1aR in PVN in cardiovascular control in response to stress. Experiments were performed in male Wistar rats equipped with radiotelemetric device. The right PVN was transfected with adenoviral vectors (Ads) engineered to over-express V1aR along with an enhanced green fluorescent protein (eGFP) tag. Control groups were PVN transfected with Ads expressing eGFP alone, or wild-type rats (Wt). Rats were recorded with and without selective blockade of V1aR (V1aRX) in PVN under both baseline and stressed conditions. Blood pressure (BP), heart rate (HR), their short-term variabilities, and baroreflex sensitivity (BRS) were evaluated using spectral analysis and the sequence method, respectively. Under baseline physiological conditions,V1aR rats exhibited reduced BRS and a marked increase of BP and HR variability during exposure to stress. These effects were all prevented by V1aRX pretreatment. In Wt rats, V1aRX did not modify cardiovascular parameters under baseline conditions, and prevented BP variability increase by stress. However, V1aRX pretreatment did not modify baroreflex desensitization by stress in either rat strain. It follows that increased expression of V1aR in PVN influences autonomic cardiovascular regulation and demarcates vulnerability to stress. We thus suggest a possible role of hypothalamic V1aR in cardiovascular pathology.
Rice production is decreasing by abiotic stresses like heavy metals. In such circumstances, producing food for growing human population is a challenge for plant breeders. Excess of Al3+ in soil has become threat for high yield of rice. Improvement of crop is one of potential solution for high production. The aim of this study was to develop the new method for optimization of Al3+ toxicity tolerance in indica rice at germination stag using two-way ANOVA and Duncan's multiple-range test (DMRT). Seeds of two indica rice cultivars (Pokkali and Pak Basmati) were exposed in different concentrations (control, 5 mM, 15 mM, and 20 mM) of Al3+ toxicity at pH 4 ±0.2 for two weeks. Germination traits such as final germination percentage (FG%), germination energy (GE), germination speed (GS), germination index (GI), mean time of germination (MGT), germination value (GV), germination velocity (GVe), peak value of germination (GPV), and germination capacity (GC) and growth traits such as root length (RL), shoot length (SL), total dry biomass (TDB), and germination vigour index (GVI) were measured. To obtain the maximum number of significance (≤ 0.01%) parameters in each concentration of Al3+ toxicity with control, two-way ANOVA was established and comparison of mean was done using DMRT. The results showed that 5 mM, 10 mM, and 15 mM have less significant effects on the above-mentioned parameters. However, 20 mM concentration of Al3+ produced significant effects (≤ 0.01%). Therefore, 20 mM of Al3+ is considered optimized limit for indica cultivars (Pokkali and Pak Basmati).
KEY MESSAGE: Three tau class MaGSTs responded to abiotic stress, MaGSTF1 and MaGSTL1 responded to signaling molecules, they may play an important role in the growth of banana plantlet. Glutathione S-transferases (GST) are multifunctional detoxification enzymes that participate in a variety of cellular processes, including stress responses. In this study, we report the molecular characteristics of five GST genes (MaGSTU1, MaGSTU2, MaGSTU3, MaGSTF1 and MaGSTL1) cloned from banana (Musa acuminate L. AAA group, cv. Cavendish) using a RACE-PCR-based strategy. The predicted molecular masses of these GSTs range from 23.4 to 27.7 kDa and their pIs are acidic. At the amino acid level, they share high sequence similarity with GSTs in the banana DH-Pahang (AA group) genome. Phylogenetic analysis showed that the deduced amino acid sequences of MaGSTs also have high similarity to GSTs of other plant species. Expression analysis by semi-quantitative RT-PCR revealed that these genes are differentially expressed in various tissues. In addition, their expression is regulated by various stress conditions, including exposure to signaling molecules, cold, salinity, drought and Fusarium oxysporum f specialis(f. Sp) cubense Tropical Race 4 (Foc TR4) infection. The expression of the tau class MaGSTs (MaGSTU1, MaGSTU2 and MaGSTU3) mainly responded to cold, salinity and drought while MaGSTF1 and MaGSTL1 expressions were upregulated by signaling molecules. Our findings suggest that MaGSTs play a key role in both development and abiotic stress responses.
An experiment was conducted to determine the effects of period on the performance, immunity, and some stress indicators of broilers fed 2 levels of protein and stocked at a normal or high stocking density. Experimental treatments consisted of a 2 × 2 × 2 factorial arrangement with 2 levels of prebiotic (with or without prebiotic), 2 levels of dietary CP [NRC-recommended or low CP level (85% of NRC-recommended level)], and 2 levels of stocking density (10 birds/m(2) as the normal density or 16 birds/m(2) as the high density), for a total of 8 treatments. Each treatment had 5 replicates (cages). Birds were reared in 3-tiered battery cages with wire floors in an open-sided housing system under natural tropical conditions. Housing and general management practices were similar for all treatment groups. Starter and finisher diets in mash form were fed from 1 to 21 d and 22 to 42 d of age, respectively. Supplementation with a prebiotic had no significant effect on performance, immunity, and stress indicators (blood glucose, cholesterol, corticosterone, and heterophil:lymphocyte ratio). Protein level significantly influenced broiler performance but did not affect immunity or stress indicators (except for cholesterol level). The normal stocking density resulted in better FCR and also higher antibody titer against Newcastle disease compared with the high stocking density. However, density had no significant effect on blood levels of glucose, cholesterol, corticosterone, and the heterophil:lymphocyte ratio. Significant interactions between protein level and stocking density were observed for BW gain and final BW. The results indicated that, under the conditions of this experiment, dietary addition of a prebiotic had no significant effect on the performance, immunity, and stress indicators of broilers.
An investigation was made to see the salt tolerance of 10 weed species of rice. Properly dried and treated seeds of weed species were placed on 9 cm diameter petridishes lined with Whatman No. 1 filter paper under 6 salinity regimes, viz. 0 (control), 4, 8, 16, 24 and 32 dS m(-1). The petri dishes were then kept in germinator at 25 +/- 1.0 degrees C and 12 hr light. The number of germinated seeds were recorded daily. The final germination percentage, germination index (GI), seedling vigour index, mean germination time and time for 50% germination were estimated. Root and shoot lengths of the weed seedlings were measured at 20 days after salt application and relative growth values were calculated. Results revealed that salinity decreased final germination percentage, seed of germination as measured by GI, and shoot and root length in all the species. Germination of most of the weed seeds was completely arrested (0) at 32 dS m(-1) salinity except in E. colona (12%) and C. iria (13.9%). The species C. iria, E. colona, J. linifolia and E. crusgalli showed better germination (above 30%) upto 24 dS m(-1) salinity level and were regarded as salt-tolerant weed species. J. linifolia, F. miliacea, L. chinensis and O. sativa L. (weedy rice) were graded as moderately tolerant and S. zeylanica, S. grosus and C. difformis were regarded as least tolerant weed species.