Endogenous Growth Regulator Detection In Guinea Grass Seeds

Endogenous growth regulator activity/level was detected in guinea grass (Panicum maximum Jacq.) seeds, a species widely used as a forage crop in the tropics, aiming at explaining its high seed dormancy level. Seeds were previously scarified or not with sulphuric acid and osmoconditioned on PEG-6000. Endogenous growth regulators were detected as follow: gibberellin-like activity (growth of lettuce hypocotyl bioassay); cytokinins (increase of fresh mass of radish cotyledon bioassay); ABA (spectrophotometer at 230 nm). Exogenous application of GA3 showed a germination increasing effect while ABA had a complete effectiveness to prevent it. High-dormancy seed samples had higher gibberellin-like activity than low-dormancy ones and intact seeds showed higher gibberellin-like activity than scarified seeds; however, after osmoconditioning, opposite results were recorded. No significant activity of neutral promoters and cytokinins was detected. Average levels of ABA for untreated, osmoconditioned after zero- and two-month-storage seed samples were 0.51, 0.39 and 0.21 mg.100 kg-1, respectively. Chemical scarification did not alter either ABA levels in high-dormancy seed samples (0.66 mg.100 kg-1) or those of low-dormancy (0.23 mg.100 kg-1), the former being significantly higher than the latter. Finally, the results show that a gibberellin-ABA interaction appears to be the main factor accounting for dormancy, germination and osmoconditioning control in guinea grass seeds.327695700Basra, A.S., Sarlach, R.S., Malik, C.P., Seed germination of Panicum maximum Jacq. in relation to respiratory inhibitors and gibberellic acid treatments (1989) Indian Journal of Plant Physiology, 32, pp. 139-143Black, M., The role of endogenous hormones in germination and dormancy (1980) Israel Journal of Botany, 29, pp. 181-192Braun, J.W., Khan, A.A., Endogenous abscisic acid levels in germinating and nongerminating lettuce seeds (1975) Plant Physiology, 56, pp. 731-733Dhir, K.K., Sharma, R., ABA-caused inhibition of seedling growth and its removal by kinetin (1991) Proceedings of the National Symposium on Growth and Differentiation in Plants, pp. 71-73. , DHIR, K.K.DUA, I.S.CHARK, K.S. (Eds.). New trends in plant physiology. New Delhi, India: Today and Tomorrow's Printers & PubDurán, J.M., Tortosa, M.E., The effect of mechanical and chemical scarification on germination of charlock (Sinapsis arvensis L.) seeds (1985) Seed Science & Technology, 13, pp. 155-163Finch-Savage, W.E., McQuistan, C.I., Abscisic acid: An agent to advance and synchronise germination for tomato (Lycopersicon esculentum Mill.) seeds (1991) Seed Science & Technology, 19, pp. 537-544Frankland, B., Wareing, P.F., Effect of gibberellic acid on hypocotyl growth of lettuce seedlings (1960) Nature, London, 185, pp. 255-256Hardegree, S.P., Drying and storage effects on germination of primed grass seeds (1994) Journal of Range Management, 47 (3), pp. 196-199Harty, R.L., Hopkinson, J.M., English, B.H., Alder, J., Germination, dormancy and longevity in stored seeds of Panicum maximum (1983) Seed Science & Technology, 11, pp. 341-351Hilhorst, H.W.M., Karssen, C.M., Seed dormancy and germination: The role of abscisic acid and gibberellins and the importance of hormone mutants (1992) Plant Growth Regulation, 11, pp. 225-238Jan, R.C., Amen, R.D., What is germination? (1977) The Physiology and Biochemistry of Seed Dormancy and Germination, pp. 7-28. , KHAN, A.A. (Ed.). Amsterdam: North-Holland PubJones, R.L., Stoddart, J.L., Gibberellins and seed germination (1977) The Physiology and Biochemistry of Seed Dormancy and Germination, pp. 77-110. , KHAN, A.A. (Ed.). Amsterdam: North-Holland PubKefeli, V.I., (1978) Natural Plant Growth Inhibitors and Phytohormones, 277p. , Boston: W. Junk PubKhan, A.A., Primary, preventive and permissive roles of hormones in plant systems (1975) Botanical Review, 41, pp. 391-420Le-Page-Degivry, M.T., Rôle des gibbérellines et de l'acide abscissique dans la germination et la dormance des sementes: Pour une approche dynamique (1990) Seed Science & Technology, 18, pp. 345-356Letham, D.S., Shannon, J.S., McDonald, I.R., The structure of zeatin, factor inducing cell division (1968) Proceedings of the Chemical Society, pp. 230-231Murti, G.S.R., Endogenous abscisic acid in seed in relation to seed and fruit growth in acid lime (1993) Indian Journal of Plant Physiology, 36, pp. 9-11Ross, J.D., Metabolic aspects of dormancy (1984) Germination and Reserve Mobilization: Seed Physiology, 2, pp. 45-75. , MURRAY, D.R. (Ed.). Sidney: Academic PressSokal, R.R., Rohlf, F.J., (1969) Biometry, 776p. , San Francisco: Freeman and CoSondheimer, R., Tzou, D.S., Galson, E.D., Abscisic acid levels and seed germination (1968) Plant Physiology, 43, pp. 1443-1447Thomas, T.H., Cytokinins, cytokinins-active compounds and seed germination (1977) The Physiology and Biochemistry of Seed Dormancy and Germination, pp. 111-144. , KHAN, A.A. (Ed.). Amsterdam: North-Holland PubToyomasu, T., Yamane, H., Murofushi, N., Inoue, Y., Effects of exogenously applied gibberellin and red light on the endogenous levels of abscisic acid in photoblastic lettuce seeds (1994) Plant and Cell Physiology, 35, pp. 127-129Valio, I.F.M., Schwabe, W.W., Promotion and inhibition of growth in Lunularia cruciata (L.) DUM.VII - The isolation and bioassay of lunularic acid (1970) Journal of Experimental Botany, 21, pp. 138-150Webb, D.P., Van Staden, J., Wareing, P.F., Seed dormancy in Acer: Changes in endogenous cytokinins, gibberellins and germination inhibitors during the breaking of dormancy of Acer saccharum March (1973) Journal of Experimental Botany, 24, pp. 105-106Wood, T., A reagent for the detection of chloride and certain purines and pyrimidines on paper chromatograms (1955) Nature, London, 176, pp. 175-17

Germination Of Coffee Seeds (coffea Arabica L. Cv. Mundo Novo)

The life-span of coffee seeds is extended when seeds are stored with high moisture content. Germination in darkness is always higher than in the light. Exogenous gibberellic acid and abscisic acid inhibit germination while kinetin reverses this inhibitory effect. Low levels of endogenous gibberellin- and abscisic acid-like and high levels of cytokinin-like substances favour germination while the opposite combination of regulators delays germination. © 1976 Oxford University Press.27598399

Correlative Growth In Seedlings Of Phaseolus Vulgaris L.: Inhibition Of Stem Growth By The Primary Leaves

Primary leaves of one-week-old seedlings of dwarf beans effectively inhibit stem elongation either in natural daylight or in continuous darkness. Stem elongation is promoted by exogenous gibberellic acid and kinetin and inhibited by indol-3-ylacetic acid (IAA) or abscisic acid, and it is suggested that IAA is the inhibitory substance emanating from the primary leaf blades which affects the growth of the stem. © 1978.4217826326

Influence Of Temperature And Photoperiod On Flowering And Tuberous Root Formation Of Pachyrrhizus Tuberosus

P. tuberosus, a native species of the Amazon region, was cultivated under different thermal regimes and photoperiods in an attempt to relate these stimuli to flower initiation and tuberous root formation. It is shown that P. tuberosus is an intermediate-day plant (flowers only under photoperiods above 9 h and below 16 h). With regard to tuberization P. tuberosus may be considered a short-day plant: tuberization occurs only in photoperiods below 16 h. High thermal regimes 30/25 °C (13 h day/11 h night) delay and reduce flowering and completely inhibit tuberous root formation. Thermal regimes of 25/20 °C and 20/15 °C (13 h day/11 h night) were the most suitable for flowering and tuberization. © 1989 Annals of Botany Company.64441141

Effects Of Moisture Content On Germination Of Seeds Of Hancornia Speciosa Gom. (apocynaceae)

Seeds of Hancornia speciosa germinated best at a temperature of 20-30 °C. The viability of the seeds during storage was short and the best storage conditions for viability entailed keeping the seeds in polyethylene bags. Seed viability was maintained only when the seeds were stored at a moisture content above 30%; storage conditions which allowed dehydration resulted in a rapid loss of viability (the seeds showed recalcitrant behaviour).Low temperature during storage did not improve longevity. A relationship between germination and moisture content was established, but when the moisture content fell below 25% there was a drastic reduction of germination. After 9 weeks of storage, even at high moisture content, seeds lost viability.Loss of seed viability during seed dehydration was associated with increased leakage of electrolytes and organic solutes, and reduced tetrazolium staining during subsequent imbibition. © 1992 Annals of Botany Company.6911