The radicle emergence test and storage longevity of cucurbit rootstock seed lots

A study was carried out to test whether a single count of radicle emergence (RE test) would correlate with the storage potential of seed lots of cucurbit (C. maxima × C. moschata) rootstock cultivars. The RE test was performed by counting radicle emergence percentage between 26 and 100 hours of germination. Seed longevity was determined by storage at 75% relative humidity at 35°C over 100 days, with seed survival curves constructed based on normal germination percentages. Ki (estimated initial viability in probits), σ (standard deviation of the normal distribution of seed death in time) and p50 (time for viability to fall to 50%) were determined through probit analysis. Correlation analysis showed that RE counts particularly between 30 and 34 hours were highly (P < 0.01) correlated with normal germination percentage, Ki and p50. It can be concluded that RE tests can be used as an indicator of subsequent seed lot longevity in cucurbit rootstock seed cultivars.

Evaluation of rice genotypes on seed attributes and agronomic performance for developing direct-seeded cultivar

<abstract> <p>Direct seeding of rice (DSR) may give benefit in using water and labor more efficient and reduce production costs. This study purposes to investigate the character of the seeds, their early vigor traits, the growth and development of rice plants for developing DSR cultivar. The research was conducted in four stages: the measurement of the size of the seed, endosperm, and embryo; the germination test in the laboratory; seedling test using experimental pots; and testing the agronomic performance on transplanting and direct seeding methods in a plastic house. Seed material used eight breeding lines of IPB University and two released varieties. The results of study showed that each genotype had different characteristics of seed, endosperm, and embryo in both weight and area. Seed weight becomes the most dominant in the emergence of superior EV traits, whereas the more seed weight indicates faster radicle emergence and more weight of seedling. DSR method compared to transplanting showed performance such as taller plant, higher leaf area and photosynthesis rate at early growth stage, earlier heading time, and higher plant dry weight since early growth until 65 days old. The seed characters have positively correlation to dry weight of seedlings, number of leaves, leaf area, and canopy dry weight. We also found that higher area of endosperm and embryo significantly correlated to have faster plumule emergence, higher leaf area and plant height. Candidate genotypes for DSR would be further investigated in the field trial agronomically.</p> </abstract>

An Automatic Method for Rice Seed Vigor Classification Via Radicle Emergence Testing Using Image-Processing, Curve-Fitting and Clustering Methods

Background: Rice seed vigor classification is important for seed storage management by seed producers and by farmers while planning their cultivation activities. Field emergence is a direct method of seed vigor testing but is laborious, time-consuming and subjective. The accelerated aging (AA) test is often used as an indirect method for rice seed vigor classification in the laboratory. However, the results from this method are often imprecise. This paper presents the SVRice package, a simple, cost-efficient and flexible procedure that utilizes computer image analysis for high-throughput, automatic rice seed vigor classification. SVRice consists of 4 steps: dynamic imaging, image processing, curve fitting and clustering. Seed vigor was classified based on radicle emergence indices, such as maximum radicle emergence (MaxRE), mean radicle emergence time (MRET), radicle emergence speed (t50), uniformity of radicle emergence (U7525), and area under the curve of the radicle emergence fitted curve (AUC).Results: Parameters used to classify rice seed vigor, such as MRET, U7525 and t50, were strongly negatively correlated with the saturated salt accelerated aging (SSAA) test. A germination time of 90 hours at 25°C was sufficient for effective classification based on SVRice, whereas the SSAA test took approximately 400 hours to complete. The SVRice software algorithm was created to be especially suitable for assessment after 6 months under controlled atmosphere storage (at 15°C and 37% RH in a hermetic bag). The study showed that SVRice could unambiguously classify 40 indica rice samples with different varieties, production years, production sites, storage times and storage conditions compared with the SSAA test.Conclusions: This paper confirmed the accuracy, reproducibility and flexibility of the SVRice package for automatic seed vigor classification of Oryza sativa seeds; moreover, it is also likely applicable to other species as a viable alternative to current methods that require more time and are less precise.

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.

Does the lag time between radicle and epicotyl emergences in acorns of pedunculate oak (Quercus robur L.) depend on the duration of cold stratification and post-stratification temperatures? Modelling with the sigmoidal growth curves approach

The objective of this study was to determine how the current (10–16 weeks) and predicted future (2–8 weeks) length of cold stratification and current and predicted future post-stratification temperatures influence radicle and epicotyl emergence in acorns of Quercus robur. We tested radicle and epicotyl emergence at two temperatures corresponding to the current (15/6°C) and predicted future early autumn and spring temperatures (25/15°C) in Poland. We fitted models to describe and derive parameters for radicle and epicotyl emergences over time. The parameters included maximum percentage, rate of emergences, time to achieve the maximum emergence rate, emergence delay and time to 50% emergence. In most cases, the Gompertz model was the best fit, but in a few cases, the logistic model was the best. Richard's model for most of the cases did not converge. This model, according to both information criteria values, was the best fit for epicotyl emergence at 15/6°C following 8 weeks of cold stratification. Richard's model was also the best fit for epicotyl emergence at 25/15°C following 14 weeks of stratification.. Our results indicate that at temperatures typical for early autumn (15/6°C), the time necessary for radicle emergence from 50% of acorns was longer than that from acorns placed at 25/15°C. Four weeks of cold stratification extended 50% radicle emergence at 15/6°C to 70 d, whereas 12 weeks of stratification shortened the time to 11 d. When the acorns were incubated at 25/15°C, radicle emergence occurred faster than at 15/6°C and the time lag between radicle and epicotyl was shorter.

Nucleoside Metabolism Is Induced in Common Bean During Early Seedling Development

Nucleoside hydrolases (NSH; nucleosidases) catalyze the cleavage of nucleosides into ribose and free nucleobases. These enzymes have been postulated as key elements controlling the ratio between nucleotide salvage and degradation. Moreover, they play a pivotal role in ureidic legumes by providing the substrate for the synthesis of ureides. Furthermore, nucleotide metabolism has a crucial role during germination and early seedling development, since the developing seedlings require high amount of nucleotide simultaneously to the mobilization of nutrient in cotyledons. In this study, we have cloned two nucleosidases genes from Phaseolus vulgaris, PvNSH1 and PvNSH2, expressed them as recombinant proteins, and characterized their catalytic activities. Both enzymes showed a broad range of substrate affinity; however, PvNSH1 exhibited the highest activity with uridine, followed by xanthosine, whereas PvNSH2 hydrolyses preferentially xanthosine and shows low activity with uridine. The study of the regulation of nucleosidases during germination and early postgerminative development indicated that nucleosidases are induced in cotyledons and embryonic axes just after the radicle emergence, coincident with the induction of nucleases activity and the synthesis of ureides in the embryonic axes, with no remarkable differences in the level of expression of both nucleosidase genes. In addition, nucleosides and nucleobase levels were determined as well in cotyledons and embryonic axes. Our results suggest that PvNSH1 and PvNSH2 play an important role in the mobilization of nutrients during this crucial stage of plant development.

An Automatic Method for Rice Seed Vigor Classification Via Radicle Emergence Test Using Image Processing, Curve Fitting and Clustering Method

Background: Rice seed vigor classification is important for seed storage management by seed producers and by farmers planning their cultivation activities. Field emergence is a direct method of seed vigor testing but is laborious, time-consuming and subjective. The saturated salt accelerated aging (SSAA) test is often used as an indirect method for rice seed vigor classification in the laboratory. However, the results from such a method are often imprecise. This paper presents the SV-RICE package, a simple, cost-efficient and flexible procedure that utilizes computer image analysis for high-throughput, automatic rice seed vigor classification. SV-RICE consists of 4 steps: dynamic imaging, image processing, curve fitting and clustering. Seed vigor has been classified based on radicle emergence indices, such as maximum radicle emergence (MRET), mean radicle emergence time (MaxRE), radicle emergence speed (t50), uniformity of radicle emergence (U7525), and area under the curve of the radicle emergence fitted curve (AUC).Results: Parameters used to classify rice seed vigor, such as MRET, U7525 and t50, were strong negative correlation with the SSAA test. The germination time of 90 hours, at 25°C, was sufficient for effective classification based on SV-RICE, whereas the SSAA test takes approximately 400 hours to complete. The SV-RICE software algorithm was set up to be especially suitable for assessment after 6 months under controlled atmosphere storage (at 15°C and 37%RH in hermetic bag). The study showed that SV-RICE could unambiguously classify 40 Indica rice samples with different varieties, production years, production sites, storage times and storage conditions compared to the SSAA test.Conclusions: This paper confirmed the accuracy, reproducibility and flexibility of the SV-RICE package for automatic seed vigor classification of Oryza sativa seeds; however, it is likely applicable to other species as a viable alternative to current methods that require more time and are less precise.

Early counts of radicle emergence, counted manually and by image analysis, can reveal differences in the production of normal seedlings and the vigour of seed lots of cauliflower

The ability of a single early count of radicle emergence (RE) to predict differences in the production of normal seedlings (NG) and seed vigour was examined in four seed lots from each of three varieties of cauliflower (Brassica oleracea var botrytis). Initial seed quality was assessed in germination and controlled deterioration (CD) vigour tests. RE (first appearance of the radicle) was counted manually after 48 hours in the germination test (RE 48h 20/30&deg;C) and every two hours for 144 hours at 20&deg;C using automated image analysis. Seed vigour was assessed in field and glasshouse trials. A large proportion of the variance in NG was explained by the RE count. The same RE counts at 20/30&deg;C and 20&deg;C predicted seed vigour in the field and glasshouse and revealed the same vigour differences as the validated CD test. Differences in vigour (field and glasshouse emergence) observed between varieties were related to the extent of previously sustained seed ageing revealed by the CD test, although genotypic differences in vigour could not be excluded. We propose that single counts of RE taken manually or by image analysis can be used to reveal differences in the NG and vigour of seed lots of cauliflower.