Differential Energy Allocation Among 15 New Guineagrass (Panicum Maximum Jacq.) Hybrids

The main aim of this research work was to determine trends of energy allocation among newly developed guineagrass (Panicum maximum Jacq) hybrids, ranging from very-early to late-flowering genotypes. Besides the flowering cycle, eight phenological and two seed quality traits were scored in a greenhouse randomized complete block experiment including plant height (PH), reproductive tiller number/overall tiller number (RTN/OTN), panicle number/reproductive tiller (PN/RT), leaf length (LL), leaf width (LW), panicle length (PL), fresh weight (FW), dry weight (DW), number of seeds/gram (NS/G) and seed sample physical purity (SPP). Very-early and early-flowering hybrids consistently showed the highest correlations values between flowering cycle and RTN/OTN (r= - 0.59**), PN/RT (r= - 0.48**), NS/G (r= - 0.88**) and SPP (r= - 0.80**) (reproductive functions) while intermediate and lateflowering hybrids showed the highest values for LL (r= 0.53**), LW (r= 0.60**), PL (r= 0.77**), FW (r= 0.78**) and DW (r= 0.85**) (vegetative functions). The implications of these results for plant breeding and forage management purposes are discussed

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

Effects of a Recurrent Selection Scheme, Applied to an Interspecific Hybrid \u3cem\u3ePennisetum Purpureum\u3c/em\u3e Schum. (Elephantgrass) \u3cem\u3ex Pennisetum Glaucum\u3c/em\u3e (L.) R. Br. Stuntz (Pearl Millet), on Several Seed Quality Parameters

Elephantgrass cultivars and introductions show practically no viable pure seeds and their uses in cultivated grasslands are exclusively dependent on vegetative propagation. Therefore, in large areas, sowing operation costs make unfeasible setting up new pastures. On the other hand, pearl millet is a high seed producer species though presenting some forage constraints (poor forage production, low regrowth potential after cutting or grazing and low field persistence). Recently, an hexaploid interespecific hybrid between the two species was developed (Schank & Diz, 1996), which is able to produce viable pure seeds, in variable amounts according to the genotype considered (Diz & Schank, 1995). This research aimed to check several seed quality parameters in two selected populations, derived from the original F2 interespecific hybrid population

Yield and Quality Parameters of an Interspecific Hybrid \u3cem\u3ePennisetum Purpureum\u3c/em\u3e Schum. (Elephant-Grass) \u3cem\u3eX Pennisetum Glaucum\u3c/em\u3e (L.) R. Br. Stuntz (Pearl Millet)

Elephant-grass is a tropical forage grass used either as a supplement fodder or for direct grazing. It usually shows regular nutritive value (6-13% crude protein, CP, and 55-60% forage digestibility) (Alcantara et al., 1981). Most of the available cultivars produce no viable seeds. On the other hand, pearl millet has high seed yielding potential along with high quality forage (\u3e15% CP and 70% forage digestibility). However, it shows poor forage production, low field persistence under grazing and low regrowth potential after cutting or grazing. During the 90\u27s, an interspecific hybrid between the two species was developed, trying to combine the elephant-grass adaaptability and forage yielding potential with the pearl millet forage quality and seed yielding potential (Schank et al., 1993; Schank, 1996). The new genetic material was able to produce viable seeds in variable amounts (Diz et al., 1995). The main aim of this research was to produce selected populations with high phenotypic uniformities, showing high average forage production and quality

Seed controlled deterioration of three interspecific elephant grass x pearl millet hybrids

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)In order to allow using seeds from three interspecific elephant grass x pearl millet hybrids (Original, Cutting and Grazing-types) to set pasture fields, it became necessary to analyze their performances in relation to storage conditions and controlled deterioration. Five moisture content levels and three storage temperatures (40, 50 and 65 degrees C) have been tested for each hybrid. Seed sub samples for each moisture content and storage temperature combination were sealed in laminated aluminum foil packages and stored at those temperatures until complete survival curves have been obtained. The recurrent selection increased seed initial quality (Ki) for grazing-type population (lower and more tillered plants); however inverse results were observed for cutting-type population (higher and less tillered plants). Viability equation constants estimated for Cutting-type, Original and Grazing-type hybrids are: K(E) = 8.417, 7.735 and 8.285; C(w) = 5.037, 4.658 and 4.522; C(H) = 0.02309, 0.01969 and 0.03655; C(Q) = 0.000436; 0.000403 and 0.000300, respectively. The viability equation constants for the hybrids are K(E) = 8.033; C(w) = 4.662; C(H) = 0.02544; C(Q) = 0.000386. Through the equations, it is feasible to estimate the germination percentage of a seed lot after different storage conditions.383428434Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Physical and Quality Seed Traits Observed in New Pigeon Pea (\u3cem\u3eCajanus Cajan\u3c/em\u3e) Hybrids

Pigeon pea seed production may be affected by factors such as % of pure seeds, mean seed weight, incidence of pests and diseases and environmental stresses. Harvested seeds from different cultivars may also vary in germination %, hardseededness and germination speed. Hardseededness (seed coat impermeability to water) commonly occurs in forage legume species (Hopkinson, 1993). There is considerable variation among different entries for seed characters but this is not considered within genetic materials. This research analysed harvested seeds of selected individuals of two segregating F2 pigeon pea populations for the above cited traits and assessed the range of variation for them resulting from the hybridisation process

Differential Behaviour of Guineagrass (\u3cem\u3ePanicum Maximum Jacq.\u3c/em\u3e) Hybrids, With Different Al\u3csup\u3e+3\u3c/sup\u3e Reactions, as to Major Nutrient Translocations to the Leaves

Most of the Brazilian cultivated pasture fields presents soils with high Al+3 levels and liming is economically unfeasible. So, there is an urgent need for grasses with good forage yielding potentials that can withstand Al+3 deleterious effects (abnormal root development: short, thick and poorly branched roots, which are unable to effectively translocate water and essential nutrients to the leaves) (Foy, 1984); as a consequence, susceptible genetic materials have their field persistences greatly affected, mainly during drought periods. Researches on Al+3 reaction are usually compare supposedly resistant/tolerant genotypes with a resistant control check; doing so, the genotypic effect is not isolated, making unreliable the comparisons made (Thomas & Lapointe, 1989). Guineagrass hybrids were tested as to nutrient translocations to the leaves, through comparisons of results obtained in treatments with and without N, P and K applications to the soil, for each genotype