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

Paterniani, R S

Usberti, J A, Jr

Usberti, R

English

University of Kentucky

4-47 Session 4 - Conventional and Novel Methodologies for Plant Improvementwhile counting (days-to-flowering, panicle number/reproductive tiller andnumber of seeds/gram) and percentage data (reproductive tiller number/overalltiller number and seed sample physical purity) were transformed to vx andarc sin vx/100, before statistical analysis. An ANOVA computer programwas used to test differences among hybrids and mean comparisons of differentcharacteristics were made using Duncan’s multiple range test. Finally, singlecorrelation coefficients were calculated among flowering cycles and all thequantitative traits studied.RESULTS AND DISCUSSIONThe hybrids studied were ranked in four different groups according to theirflowering cycle: late-, intermediate-, early- and very early-flowering typesusing statistical analysis and/or consideration of other forage traits. Five ofthem (H-12, H-21, H-32, H-54 and H-64) were classified as late-flowering,five as intermediate-flowering (H-10, H-13, H-56, H-79 and H-55), three asearly-flowering (H-140, H-22 and H-42) and two (H-31 and H-33) as veryearly-flowering types (Table 1). Plant height varied from 2.47 m (H-56) to3.40 m (H-54); reproductive tiller number/overall tiller number, from 26.31%(H-38) to 85.99% (H-22); panicle number/reproductive tiller, from 1.21 (H-64) to 3.41 (H-22); leaf length, from 34.73 cm (H-140) to 90.90 cm (H-64);leaf width, from 1.77 cm (H-22) to 3.53 cm (H-13); panicle length, from20.06 cm (H-140) to 55.23 cm (H-64); fresh weight, from 392.4 grams (H-140) to 1,184.6 grams (H-64); dry weight, from 116.0 grams (H-140) to460.6 grams (H-64); number of seeds/gram, from 705 (H-21) to 1,288 (H-31) and seed sample physical purity, from 4.8% (H-54) to 87.2% (H-31).The genetic materials used revealed wide genetic diversity for all theparameters under study, similar to that observed among cultivars/ecotypes ofthe same species (Costa et al., 1989; Alcantara et al., 1991; Segui et al., 1992;Sun and Liddle, 1993). High and positive simple correlations were calculatedamong flowering cycle and plant height (r= 0.524**); leaf length (r= 0.532**);leaf width (r= 0.609**); panicle length (r= 0.775**); fresh weight (r= 0.788**)and dry weight (r= 0.857**) (Table 2). Late- and intermediate-floweringhybrids allocated most of the produced energy to vegetative functions. Onthe other hand, highly significant negative correlations were observed amongflowering cycle and reproductive tiller number/overall tiller number (r= -0.592**); panicle number/reproductive tiller (r= - 0.484**); number of seeds/gram (r= - 0.881**) and seed sample physical purity (r= - 0.807**). As theresult, early- and very early-flowering hybrids allocated most of their producedenergy to reproductive functions. Based on these results, the best strategy topreserve the variability within the species should be strongly linked to theflowering cycle of the available genetic materials. These results also suggestpotential parentals for future crossings and provide information on thedevelopment of early stage-selection schemes. Higher flexibility in foragemanagement is possible by knowing the flowering cycle of the cultivars/ecotypes to be used. For example, early- and very early- flowering genotypesshould be utilized in situations where higher stocking rates, shorter grazingand longer rest periods are desirable, because of their lower forage productionand higher reseeding potential, as compared to those of intermediate- andlate-flowering genotypes.REFERENCESAlcantara, P.B.; A.R.P. de Almeida and O.M.A.A. Ghisi. 1991. Algumasmedidas morfofisiologicas em seis cultivares de Panicum maximum Jacq..Revista de Agricultura 66: 47-63.Bayorbor, T.B.; S. Kumai; R. Fukumi and J. Hattori. 1992. Herbageyield, chemical composition and in vitro dry matter digestibility of panicgrasses, under 3-cut harvest system and during regrowth period. Journal ofJapanese Society of Grassland Science 38: 315-326.Costa, J.C.G.; Y.H. Savidan; L. Jank and L.H.R. Castro. 1989.Morphological studies as a tool for the evaluation of wide tropical foragegrass germplasms. Proc. 16th. Int. Grass. Cong., Nice, France, p. 277-278.ABSTRACTThe main aim of this research work was to determine trends of energyallocation among newly developed guineagrass (Panicum maximum Jacq)hybrids, ranging from very-early to late-flowering genotypes. Besides theflowering cycle, eight phenological and two seed quality traits were scoredin a greenhouse randomized complete block experiment including plant height(PH), reproductive tiller number/overall tiller number (RTN/OTN), paniclenumber/reproductive tiller (PN/RT), leaf length (LL), leaf width (LW), paniclelength (PL), fresh weight (FW), dry weight (DW), number of seeds/gram(NS/G) and seed sample physical purity (SPP). Very-early and early-floweringhybrids consistently showed the highest correlations values between floweringcycle 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 late-flowering 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**) (vegetativefunctions). The implications of these results for plant breeding and foragemanagement purposes are discussed.KEYWORDSPlant breeding, flowering cycles, morphological/agronomic parameters, char-acter correlationsINTRODUCTIONGuineagrass (Panicum maximum Jacq.) is a warm-season perennialbunchgrass widely grown as a forage crop in tropical and warm-temperateregions of both hemispheres. Like most tropical grasses, it is a facultativeapomictic species, where apospory and pseudogamy occur during thereproductive process. Due to the important role of guineagrass in the expansionof animal production, a number of research projects have been conducted onthis species in recent years, covering a wide range of topics including: plantbreeding (Sukhchain and Sidhu, 1991; Segui and Machado, 1992; Noirot,1993; Sukhchain and Sidhu, 1993), cytology (Nakagawa et al., 1993; Hamoudet al., 1994; Naumova and Willemse, 1995), herbage yield and/or chemicalcomposition (Hill et al., 1989; Santana, 1991; Bayorbor et al., 1992; Kawamotoet al., 1992; Segui et al., 1992; Singh et al., 1995), morphology (Costa et al.,1989; Alcantara et al., 1991), trampling resistance (Sun and Liddle, 1993)and adaptation to acid soils (Thomas and Lapointe, 1989). Most of the abovestudies do not take into account flowering cycle differences among germplasmsources, making data comparisons difficult. Also, none was designed toconsider different energy allocation trends among genotypes widely variablefor specific characteristics, which is the main scope of this research.MATERIALS AND METHODSFifteen guineagrass hybrids, derived from artificial crossings amongpreviously selected highly sexual (female) and apomictic materials (male)were evaluated. Seeds of each hybrid were sown in germination boxes, filledup with a mixture of top soil, sand and organic matter (3:1:1 by volume).Fertilizer was added to soil according to analysis recommendations. Afterfour weeks, 30 individual seedlings per hybrid were transplanted to plasticbags (10 x 15 cm), filled up with the same soil mixture, and placed in agreenhouse in a randomized complete block design with three replications(ten plants per replication). During the experiment, all plastic bags werewatered daily. At the onset of the flowering period, the number of days toflowering was scored for each individual plant. As the hybrids reached fullblooming, the panicles were bagged together (in the same treatment) to avoidseed shattering. At seed harvest, eight vegetative traits (plant height,reproductive tiller number/overall tiller number, panicle number/reproductivetiller, leaf length, leaf width, panicle length, fresh and dry weight) and twoseed quality parameters (number of seeds/gram and seed sample physicalpurity) were scored in each treatment. Measurement data (plant height, leaflength, leaf width, panicle length, fresh and dry weight) were used per seID NO. 995DIFFERENTIAL ENERGY ALLOCATION AMONG 15 NEW GUINEAGRASS(PANICUM MAXIMUM JACQ.) HYBRIDSJ. A. Usberti, Jr. 1; R. Usberti 2 and R. S. Paterniani 31 Genetics Department, Instituto Agronomico, Campinas-SP, Brazil. P.O. Box 282 Central Seed Testing Laboratory, DSMM-CATI, Campinas, Brazil. P.O. Box 12913 Campinas State University  (UNICAMP) Brazil4-48 Session 4 - Conventional and Novel Methodologies for Plant ImprovementHamoud, M.A.; S.A. Haroun; R.D. Macleod and A.J. Richards. 1994.Cytological relationships of selected species of Panicum L.. BiologiaPlantarum 36: 37-45.Hill, K.; J.R. Wilson and H.M. Shelton. 1989. Yield, persistence and drymatter digestibility of some C3, C4 and C3/C4 Panicum species. TropicalGrasslands 23: 240-249.Kawamoto, Y.; T. Kinjyo; M. Ikeda; E. Miyagi; F. Hongo and Z. Koja.1992. Clipping effects on seasonal dry matter production and nutritive valuesof tall type grass species of tropical forage. Journal of Japanese Society ofGrassland Science 38:141-151.Nakagawa, H.; N. Shimizu and W.W. Hanna. 1993. Cytology of“Natsukaze” guineagrass, a natural apomictic hybrid between a sexual andan apomictic plant. Journal of Japanese Society of Grassland Science 39:374-380.Naumova,T.N. and M.T.M. Willemse. 1995. Ultrastructural characterizationof apospory in Panicum maximum . Sexual Plant Reproduction 8: 197-204.Noirot, M. 1993. Allelic ratios and sterility in the agamic complex of theMaximae (Panicoideae): evolutionary role of the residual sexuality. Journalof Evolutionary Biology 6: 95-101.Santana, R.R. 1991. Season production of 11 Panicum maximum cultivarsharvested at a 45-day interval. Journal of Agriculture of the University ofPuerto Rico 75: 61-66.Singh, D.K.; S. Virenda; P.W.G. Sale and V. Singh. 1995. Effect of cuttingmanagement on yield and quality of different selection of guineagrass(Panicum maximum Jacq.) in a humid subtropical environment. TropicalAgriculture 72: 181-187.Segui, E. and H. Machado. 1992. Estimacion de la heredabilidad en hierbade guinea (Panicum maximum Jacq.). Pastos y Forrajes 15: 191-196.Segui, E.; H. Machado and F. Blanco. 1992. Seleccion de hibridos enPanicum maximum Jacq. superiores en terminos de MS y calidad a losprogenitores. Pastos y Forrajes 15: 103-108.Sukhchain, B.S.S. and B.S. Sidhu. 1991. Combining ability studies inguineagrass. Crop Improvement 18: 23-26.Sukhchain, B.S.S. and B.S. Sidhu. 1993. Combining ability analysis forreproductive traits in guineagrass. Tropical Agriculture 70: 252-255Sun, D. and M.J. Liddle. 1993. Plant morphological characteristics andresistance to simulated trampling. Environmental Management 17: 511-521.Thomas, D. and S. Lapointe. 1989. Testing new accessions of guineagrass(Panicum maximum) for acid soils and resistance to spittlebug (Aeneolamiareducta). Tropical Grasslands 23: 232-239.PH RTN/OTN PN/RT LL LW PL FW DW NS/G SPP(m) (%) (cm) (cm) (cm) (gram) (gram) (%)FC (days)z 0.524** -0.590** -0.484** 0.532** 0.609** 0.775** 0.788** 0.857** -0.881** -0.807**t value 4.03 4.80 3.63 4.12 5.04 8.05 4.62 5.99 12.21 8.98z FC=flowering cycle; PH=plant height; RTN/OTN=reproductive tiller number/overall tiller number; PN/RT=panicle number/reproductivetiller; LL=leaf length; LW=leaf width; PL=panicle length; FW=fresh weight; DW= dry weight; NS/G=number of seeds/gram and SPP=seedsample physical purity;**  = Student t test significant at 1% probability level.HYBRID FCz PH RTN/OTN PN/RT LL LW PL FW DW NS/G SPPdays   ranking (m) (%) (cm) (cm) (cm) (gram) (gram) (%)H-12 215.7 ay     L 3.07 bc 47.67 efg 1.85 cde 75.83 cd 3.33 ab 30.57 cd 793.0  b 341,7  b 715 h 16.9 deH-21 214.8 a      L 3.10 b 36.42 gh 1.46 ef 74.83 d 3.40 ab 36.07 bc 838.8  b 347.7  b 705 h 16.1 defH-38 214.3 a      L 2.98 bcd 26.31 h 1.55 def 74.03 d 3.30 b 27.57 de 716.5  bc 290.8  bc 779 g 12.0 efH-54 205.4 ab    L 3.40 a 58.69 cde 1.29 f 90.43 a 2.77 c 49.90 a 933.1  b 343.0  b 862 ef   4.8 fH-64 198.2 b      L 3.32 a 58.13 cdef 1.21 f 90.90 a 2.70 cd 55.23 a 1184.6  a 460.6  a 838 f   6.8 efH-10 169.3 c      I 3.11 b 44.24 efg 1.39 f 81.86 bc 2.33 ef 40.70 b 820.0  b 335.3  b 857 ef 18.1 deH-13 139.4 d      I 2.80 de 67.47 bc 1.87 cd 66.40 e 3.53 a 41.53 b 551.1  cd 233.5  cd 685 h 30.0 cdH-56 137.7 de    I 2.47 f 44.25 efg 1.17 f 88.20 ab 2.37 ef 48.90 a 541.2  cd 218.2  cde 948 d 36.9 bcH-79 132.1 ef     I 2.52 f 43.27 fg 1.18 f 90.56 a 2.17 f 51.13 a 786.1  b 278.7  bcd 918 d 44.5 bcH-55 127.4 fg     I 2.58 f 51.28 defg 1.17 f 90.43 a 2.50 de 48.80 a 702.0  bc 198.8  def 911 de 41.4 bcH-140 123.4 gh    E 2.59 f 77.74 ab 2.24 bc 34.73 f 1.77 g 20.06 f 392.4  d 116.0  f 1044 c 50.4 bH-22 118.4 hi     E 2.87 cde 85.99 a 3.41 a 35.27 f 1.77 g 24.57 def 449.5  d 127.6  ef 1006 c 54.6 bH-42 115.2 i       E 2.67 ef 83.75 a 2.53 b 39.03 f 1.90 g 23.13 ef 401.0  d 138.0  ef 1133 b 74.7 aH-31   91.2 j      VE 2.96 bcd 69.20 bc 2.22 bc 38.93 f 1.83 g 23.83 ef 404.7  d 136.7  ef 1288 a 87.2 aH-33   89.8 j      VE 3.01 bc 65.43 bcd 2.32 b 40.67 f 1.80 g 24.03 ef 410.0  d 142.0  ef 1268 a 85.6 aXx 152.86 2.89 57.32 1.79 67.47 2.49 36.40 661.6 247.2 930.46 37.52CV(%)x 3.08 3.98 8.45 12.63 5.91 5.08 9.72 18.59 19.83 1.71 16.35x X=overall character mean; CV=coefficient of variation (%);y Means, in the same column, followed by different letters are statistically different, according to Duncan’s multiple range test, at 5% probability level;z FC=flowering cycle (L=late; I=intermediate; E=early and VE=very early); PH=plant height; RTN/OTN=reproductive tiller number/overall tiller number; N/RT=panicle number/reproductive tiller; LL=leaf length; LW=leaf width; PL=panicle length; FW=fresh weight; DW=dry weight; NS/G=number of seeds/gramand SPP=seed sample physical purity.Table 1Phenological and seed quality parameters recorded on 15 new  guineagrass (Panicum maximum Jacq) hybrids in a randomized complete blockexperiment.Table 2Simple correlation coefficients calculated among flowering cycle and eight phenological/two seed quality parameters on 15new  guineagrass(Panicum maximum Jacq.) hybrids.

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

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

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