Radicle emergence test as a quick vigour test to predict field emergence performance in rice (Oryza sativa L.) seed lots

An experiment was made to standardize the radicle emergence test to predict the field emergence performance in ten different seed lots [L1 to L4: high vigour lots (> 90 % germination), L5 to L7: medium vigour lots (80-90 % germination) and L8 to L10: low vigour lots (< 80 % germination)] of rice cv. CO 51. The results showed that the significant differences are observed in physiological and biochemical parameters in different seed lots. The seed vigour was classified into three groups viz., high, medium and low vigour based on the relationship between mean germination time and field emergence. When the Mean Germination Time (MGT) was < 34 hours, the field emergence was > 85 per cent, which was considered as high vigour; when the MGT was 34-35 hours, the field emergence was 80-85 per cent, that was considered as medium vigour; when the MGT was > 35 hours, the field emergence was < 80 per cent, that was considered as low vigour. The radicle emergence test (2mm radicle length) was highly negatively correlated with mean germination time (-0.930**) followed by mean just germination time (-0.852**) and electrical conductivity of seed leachate (-0.827**) and it was positively correlated with field emergence (0.894**) followed by germination (0.878**) and dehydrogenase activity (0.864**). The R2 values between seed vigour parameters and radicle emergence test were significantly higher in 2mm length of radicle emergence when compared with 1mm length of radicle emergence. Finally, the study concluded that 36 hour MGT with the attainment of 2mm radicle emergence percentage could be used as a quick method to assess rice seed lots' quality by the seed analysts and seed industry

Volatile organic compound analysis as advanced technology to detect seed quality in groundnut

An experiment was conducted to profiling the volatile organic compounds emitted from groundnut seeds during storage and also to assess the volatiles emission level during seed deterioration. Volatile organic compounds profiling of stored groundnut seeds was done through GC-MS at monthly intervals. The results showed that several volatile compounds were released from stored groundnut seeds and all the compounds are falling into eight major groups viz., alcohols, aldehydes, acids, esters, alkanes, alkenes, ketones and ethers. The study clearly demonstrated the influence of volatile organic compounds emission level on physiological and biochemical properties during storage. There was a significant decrease in physiological and biochemical quality attributes noted due to an increase in the strength of volatiles released during ageing. When the release of total volatile strength reached more than 50%, a significant reduction in physiological attributes such as germination, root and shoot length, dry matter production and vigour index were observed. With respect to biochemical properties, a significant increase in electrical conductivity of seed leachate, lipid peroxidation and lipoxygenase activity, and a decrease in dehydrogenase, catalase and peroxidase activities were observed. However, the highest reduction in all these properties was recorded when the total volatile strength reached 92.72%. The study concluded that the volatiles released during seed deterioration could be considered the signature components for detecting the seed quality during storage

Aquaporins and their implications on seeds: A brief review

Aquaporins (AQPs) are water channel proteins. They play a key role in maintaining water balance and homeostasis in cells under stress conditions in living organisms. AQPs are pore forming transmembrane proteins that facilitate water movement and various small neutral solutes across cellular membranes. Aquaporin expression and transport functions are modulated by various phytohormones mediated signalling in plants. Transcriptome analysis revealed the role of aquaporins in regulating hydraulic conductance in plant roots and leaves. Different AQPs found in the seed system have individual functions that are more time and tissue specific, ultimately helping in the seed imbibition process to complete seed germination. Seed specific TIP3s aquaporin helps to maintain seed longevity under expressional control of ABI3 during seed maturation and heat shock proteins and late embryogenic abundant proteins. Under stress circumstances, the major significance of aquaporin expression in seeds is to maintain water influx and efflux rates, as well as protein modification, post translational alterations, nutritional acquisition and allocation, subcellular trafficking and CO2 transport. The present review mainly focused on aquaporin structure, classification, role and functional activity during solute transport, reproductive organs development, plant growth development, abiotic stress response and also various roles in seeds such as seed biology, seed development and maturation, seed dormancy, seed germination and longevity

Assessment of rice (Co 51) seed ageing through volatile organic compound analysis using Headspace-Solid Phase Micro Extraction/ Gas Chromatography-Mass Spectrometry (HS-SPME/GCMS)

Seed ageing is an inevitable process that reduces seed quality during storage. When seeds deteriorate as a result of the lipid peroxidation process, it leads to produce toxic volatile organic compounds. These volatiles served as an indicator for the viability of stored seeds. With this background, the study was conducted to profile the volatile organic compounds emitted from rice seeds during storage. Volatile profiling of stored rice var. Co 51 seeds was done through Headspace-Solid phase microextraction/ Gas chromatography-mass spectrometry (HS-SPME/GCMS). The study clearly demonstrated that the significant decrease in physiological and biochemical quality attributes was noted due to an increase in the strength of volatiles released during ageing. When the release of total volatile strength reached more than 40%, a significant reduction in physiological attributes such as germination, root and shoot length, dry matter production and vigour index were observed. With respect to biochemical properties, a significant increase in electrical conductivity of seed leachate, lipid peroxidation and lipoxygenase activity, and decrease in dehydrogenase, catalase and peroxidase activities were observed. However, the highest reduction in all these properties were recorded when the total volatile strength reached to 54.90%. Finally, the study concluded that, among all the volatiles, 1-hexanol, 1-butanol, ethanol, hexanal, acetic acid, hexanoic acid and methyl ester were the most closely associated volatiles with seed deterioration. It indicates that these components could be considered the signature components for assessing the seed quality in rice during storage.

Brown Planthopper (N. lugens Stal) Feeding Behaviour on Rice Germplasm as an Indicator of Resistance

BACKGROUND: The brown planthopper (BPH) Nilaparvata lugens (Stal) is a serious pest of rice in Asia. Development of novel control strategies can be facilitated by comparison of BPH feeding behaviour on varieties exhibiting natural genetic variation, and then elucidation of the underlying mechanisms of resistance. METHODOLOGY/PRINCIPAL FINDINGS: BPH feeding behaviour was compared on 12 rice varieties over a 12 h period using the electrical penetration graph (EPG) and honeydew clocks. Seven feeding behaviours (waveforms) were identified and could be classified into two phases. The first phase involved patterns of sieve element location including non penetration (NP), pathway (N1+N2+N3), xylem (N5) [21] and two new feeding waveforms, derailed stylet mechanics (N6) and cell penetration (N7). The second feeding phase consisted of salivation into the sieve element (N4-a) and sieve element sap ingestion (N4-b). Production of honeydew drops correlated with N4-b waveform patterns providing independent confirmation of this feeding behaviour. CONCLUSIONS/SIGNIFICANCE: Overall variation in feeding behaviour was highly correlated with previously published field resistance or susceptibility of the different rice varieties: BPH produced lower numbers of honeydew drops and had a shorter period of phloem feeding on resistant rice varieties, but there was no significant difference in the time to the first salivation (N4-b). These qualitative differences in behaviour suggest that resistance is caused by differences in sustained phloem ingestion, not by phloem location. Cluster analysis of the feeding and honeydew data split the 12 rice varieties into three groups: susceptible, moderately resistant and highly resistant. The screening methods that we have described uncover novel aspects of the resistance mechanism (or mechanisms) of rice to BPH and will in combination with molecular approaches allow identification and development of new control strategies

Influence of Biopolymer Synthesized from Tamarind Seed Polysaccharide (TSP) on Physiological and Biochemical Parameters of Maize Hybrid COH(M) 8 Seeds

The experiment was conducted in Department of Seed Science and Technology, Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu during 2021. Biopolymer was synthesized from Tamarind Seed Polysaccharide (TSP) and added with different additives and coated maize seeds to know how they effect their physiological and biochemical parameters. The seeds were given with four treatments viz., T0- control (untreated seed), T1- biopolymer (B.P) - 10g kg-1, T2- B.P (10g) + Humic acid (0.3g) + Zimmu (Allium cepa × Allium sativum) leaf extract (0.5 ml) and T3- T2+ Ascorbic acid (0.2 g) and evaluated for seed quality parameters. The results of the present investigation revealed that T3 was significantly superior viz., higher percentage of germination (95%), rate of germination (31.64), seed metabolic efficiency (2.78), seedling root length (25.92 cm), seedling shoot length (15.57 cm), total biomass production (9.41 g), vigour index I (3942), vigour Index-II (94.15). This treatment also recorded highest value of biochemical parameters such as α-amylase (2.23), dehydrogenase (1.87 OD value), catalase (29.94) and peroxidase (7.00) activities. It reduced the abnormal seedlings (2%), dead seeds (3%), days to 50% germination (2.54), mean emergence time (3.02) and pathogen infection (0.25%). We concluded that maize seeds coated with T3 had better seedling establishment and may be recommended as pre sowing seed treatment under organic agriculture

Effect of Enriched TSP Polymer Seed Coating on Germination Physiology of Greengram Var. CO8

During 2023, the research was carried out under laboratory condition at the Department of Seed Science and Technology, Tamil Nadu Agricultural University, Coimbatore, to find out the effect of TSP polymer seed coating on germination physiology of green gram. The seeds were coated with TSP polymer, TSP polymer with preservatives, TSP polymer with PGRs and TSP polymer with preservatives and PGRs @ 6 g/ kg of seeds. Among the various constituents of polymer, TSP polymer with preservative (0.1% Sodium sorbate) and PGR (1.5 ppm BRs) performed better with good speed of germination and seedling vigour

Characterization of Rice (Oryza sativa L.) Germplasm for Early Seedling Vigour-related Traits under Direct Seeded Condition

In pursuit of boosting rice production while maintaining economic feasibility within resource constraints, the shift from the traditional puddled-transplanted rice system to direct-seeded rice is gaining significance. Early seedling vigour (ESV) is an important character crucial for direct-seeded rice to outcompete and suppress weed growth. This study evaluated hundred rice germplasm accessions for their early seedling vigour-related traits. Mesocotyl and coleoptile lengths, chlorophyll content, alpha-amylase, speed of emergence, shoot and root characteristics, and vigour indices exhibited notable variability as indicated by their high PCV and GCV. Moreover, they were predominantly under the influence of additive gene effects, as illustrated by their high heritability and genetic advance as per cent of mean. This suggests that these traits are heritable and could be effectively exploited through selective breeding efforts. Positive correlations were found between seedling vigour and traits like emergence (%), speed of emergence, chlorophyll content, and alpha-amylase activity. Based on PCA, Vigour index-I, II, total seedling length, and chlorophyll contents were regarded as major discriminators in rice germplasm for direct seeded traits. The superior genotypes for seedling vigour such as Honduras and Gharib, could be used as donors in the rice breeding programs to develop direct seeded rice cultivars