Ageing induces many deteriorative changes to seeds during storage like genetic damage, protein degradation, enzyme inactivation and loss of membrane integrity. In this study, we subject to investigate the alterations in seed coat structure and its permeability properties due to accelerated ageing affecting the subsequent imbibition of soybean [Glycine max (L.) Merr.] seeds. Two contrasting seed coat colour genotypes, JS 335 (white) and Bhatt (black) were selected and artificially aged for 48 and 72 h. The results of seed ageing on permeability, imbibition and germination proved that permeability and imbibition increased but germination decreased in white genotype due to imbibitional injury, whereas germination increased in black genotype due to breaking of hard seed coat imposed dormancy. The hard seeds in the black genotype with a different seed coat structure compared to the white genotype prevented imbibition injury in aged seeds by regulating permeability. Microscopic studies of seed coat structure in aged seeds revealed a thick cuticle with small hilar fissure and compact, dense hourglass cells in black genotype compared to a thin cuticle with large hilar fissure and loosely packed and distorted hourglass cells in white genotype. Thus the altered permeability and imbibition injury in artificially aged seeds is shown to occur mainly as a result of altered and damaged seed coat structure. INTRODUCTIONSeed ageing is an irreversible and inexorable process of a progressive decrease in vigour ultimately leading to the loss of seed viability (Arc et al., 2011;Lehner et al., 2008;Stewart & Bewley, 1980). The rate of seed ageing depends upon the genotype/ species, the conditions prevailing during storage like moisture content, temperature, humidity and seed composition (Roberts, 1973). It has been reported that high moisture content and high temperature accelerate seed deterioration (Ellis & Hong, 1991;Goel et al., 2003) based on which seeds are accelerated to artificially age by exposing them to high humidity and temperature of about 40-45 ˚C and 100% RH (Delouche & Baskin, 1973). Accelerated ageing is shown to induce many deteriorative changes to seeds during storage

Maize (Zea mays) is the third major cereal crop in the Indian subcontinent, but the crop yields per hectare of Indian maize cultivars are less than half of the global average due to the impurity of seed lots supplied to farmers. In this study, we discovered high-quality Single Nucleotide Polymorphic markers (SNPs) in two widely cultivated maize hybrids and their parental inbreds. Paired-end double digest restriction site-associated DNA sequencing was used to discover SNPs and a total of 30,764,454 reads with a read length of 151 bp per sample were generated. Genotyping of SNPs for maize hybrids ‘MAH 14-5’ and ‘Hema’ revealed a total of 47,812 and 15,815 Genetic Purity Analysis markers, respectively, of which 44,388 and 12,391 were unique with 3,424 being common to both hybrids. Identified SNPs were used to develop primers for Kompetitive Allele-Specific PCR genotyping assays to determine the genetic purity of 10 seed lots and the results were found to correlate with Grow-out-Tests. Thus, the SNPs discovered in this study proved reliable to test the genetic purity of commercial seed lots. Advances in plant molecular breeding tools especially ddRADseq for SNP discovery offer new opportunities to genotype existing cultivars and accelerate the production of genetically pure seeds.

The seed coat composition of white (JS 335) and black (Bhatt) soybean (Glycine max (L.) Merr) having different water permeability was studied. Phenols, tannins and proteins were measured, as well as trace elements and metabolites in the seed coats. The seed coat of Bhatt was impermeable and imposed dormancy, while that of JS 335 was permeable and seeds exhibited imbibitional injury. Bhatt seed coats contained comparatively higher concentrations of phenols, tannins, proteins, Fe and Cu than those of JS 335. Metabolites of seed coats of both genotypes contained 164 compounds, among which only 14 were common to both cultivars, while the remaining 79 and 71 compounds were unique to JS 331 and Bhatt, respectively. Phenols are the main compounds responsible for seed coat impermeability and accumulate in palisade cells of Bhatt, providing impermeability and strength to the seed coat. JS 335 had more cracked seed coats, mainly due to their lower tannin content. Alkanes, esters, carboxylic acids and alcohols were common to both genotypes, while cyclic thiocarbamate (1.07%), monoterpene alcohols (1.07%), nitric esters (1.07%), phenoxazine (1.07%) and sulphoxide (1.07%) compounds were unique to the JS 335 seed coat, while aldehydes (2.35%), amides (1.17%), azoles (1.17%) and sugar moieties (1.17%) were unique to Bhatt seed coats. This study provides a platform for isolation and understanding of each identified compound for its function in seed coat permeability.

An image analyser system was used to study the process of imbibition in Melia dubia seeds, and in comparison with the conventional method of measuring seed weight by an electronic balance. Melia dubia drupes were divided into three groups and treated accordingly: drupes with intact pericarp, drupes with punctured pericarp and naked seeds without pericarp. Using seed weight and perimeter as parameters, the imbibition process in the seed samples were described by a series of imbibition curves illustrative of the triphasic pattern of water uptake during germination. The image analyser captured small variation in seed parameters between the groups. The sensitivity and feasibility of the advanced method of using an image analyser to investigate individual seeds within a population imply that the image analyser has high potential in advancing seed biology studies.

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