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

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