Studies on seed viability and vigour in various order umbels of fennel (Foeniculum vulgare Miller)

Seeds from 15 genotypes of fennel were harvested and threshed separately with respect to umbel order and all the 60 (15 genotypes x 4 umbel orders) samples were kept in paper bags under ambient conditions. The schizocarp seeds from the different umbel orders were Subjected to various viability and vigour tests. The optimum conditions for the different tests were determined its: for germination temperatures of 25 degrees C and 20-30 degrees C, with the first and final counts at 6 and 11 days respectively; for accelerated ageing 96 h at 40 +/- 1 degrees C and 100% R.H; for electrical conductivity 24 It soaking at 25 degrees C: and for measurement of respiration rate, 120 h old seedlings were used. The seed quality decreased with increasing umbel order in all the varieties/genotypes. Thus seeds from the main and primary umbel orders had higher vigour and better performance in the laboratory and field. The lower quality seeds of secondary and tertiary umbel orders needed to be graded out during processing. Field emergence index and seedling establishment (%) were significantly and positively correlated with standard germination (%), speed of germination, seedling length (cm), seedling vigour index, accelerated ageing test (%), dehydrogenase activity test, respiration rate (mu lO(2) seedling(-1) h(-1)), and test weight (g) whereas significant and negative correlations were observed with electrical conductivity test (mu mhos/cm/seed) and seed density (g/cc). The overall results of all laboratory and field tests showed that the seeds from main and primary umbel orders should be considered as quality seeds.