Cultivar and Germplasm

Transcription

1 Cultivar and Germplasm Release RELEASE F MAIZE /ZEA MAYS L. (WALP.)] PEN-PLLINATED CULTIVAR MAYRBELA 05' James S. Beaver 2, Marcs Saliceti 3 and Jel Sud 4 J. Agrie. Univ. P.R. 90(3-4) : (2006) Maize (Zea mays L.) is a traditinal crp in Puert Ric and lcal demand fr the grain remains strng. In 999, Puert Ric imprted 270,69 f yellw dent maize (U.S. n. 2) as a feed grain fr livestck, wrth mre than $26 millin (U.S. Census Bureau, 2000). Small-scale farmers in Puert Ric ften harvest maize near physilgical maturity fr lcal vegetable markets t be used t prepare traditinal dishes. Maize harvested near physilgical maturity can be prfitable. Farmers ften btain prices f $0.20 t 0.25 per ear. The unavailability f seed f adapted cultivars is ften a cnstraint t increased maize prductin in Puert Ric. "Mayrbela' (PI 20935), a yellw flint pen-pllinated maize cultivar, was develped in the 930s frm cultivars f the Castal Trpical Flint Race utcrssed t a U.S. inbred line, fllwed by selectin (Gdman and Brwn, 988). Althugh the cultivar was never frmally released by the Puert Ric Agricultural Experiment Statin, several investigatrs have used Mayrbela in their research. Crsses amng 'Diente de Caball', Mayrbela and sutheastern and midwestern U.S. cultivars were evaluated by Mll et al. (962). Crsses between the Puert Rican maize cultivars and a sutheastern dent 'Indian Chief prduced the highest seed yields at tw lcatins in Nrth Carlina. Pllak et al. (99) fund that the Diente de Caball X Mayrbela crss had the best hetertic cmbinatin amng fur ppulatins evaluated at Isabela, Puert Ric. Fuentes et al. (998) evaluated selectin prgress fr seed yield and agrnmic traits f Mayrbela and Diente de Caball after fur cycles f reciprcal recurrent selectin. Mayrbela had the lwest seed yield reductin (6%) caused by Helicverpa zea. Rbbins and Warren (993) reprted that Mayrbela had resistance t races 0 and f nrthern crn leaf blight caused by Exserhilum turcicum. Seed f Mayrbela was btained frm the USDA-ARS Trpical Agriculture Research Statin. Tw thusand seeds f Mayrbela were planted at the Isabela Substatin in January ne hundred ears were harvested frm the nursery based n the agrnmic characteristics f the female parent. Seventy-eight f these ears were selected based n seed type. The half-sib lines fr the first cycle f mass selectin were evaluated in a nursery planted at the Isabela Substatin in Nvember A randmized cmplete blck design with 78 entries and tw replicatins was used. The experimental units cnsisted f single 5-m rw lengths spaced 76 cm apart. Twenty-five seeds were planted in each rw. Apprximately 500 kg/ha f granular fertilizer was applied at planting. Weeds were cntrlled manually and insects were cntrlled with methmyl (Nudrin) at 'Manuscript submitted t the Editrial Bard 6 December Prfessr, Department f Agrnmy and Sils, University f Puert Ric-Mayagiiez, P.. Bx 9030, Mayagüez, PR Frmer Graduate Student, currently Research Assciate, Department f Agrnmy and Sils. 4 Frmer Graduate Student, Department f Agrnmy and Sils. 253

2 254 BEAVER ET AL./RELEASE F MAIZE CULTIVAR a rate f.2 L/ha. At harvest maturity, plant and ear s f five plants in each rw were recrded. The number f ldged plants in each rw was als recrded. The number f plants and the number f ears per rw were determined and the number f ears per plant was calculated. length, seed quality and the degree f insect damage n the ears were determined based n a randm sample f five ears frm each rw. Seed quality scres were rated n a t 9 scale where = high cmmercial value, and 9 = n cmmercial value. Ears with the highest seed quality scres had an intense yellw clr. Insect damage scres were based n a t 0 scale where t 3 = very resistant, 4 t 6 = mderate resistance and 6 = susceptible (Widstrm, 967). Twenty half-sib lines were selected based n mean seed yield and seed quality scres (Table ). Samples f 00 seeds f each line were bulked and planted in an intercrssing nursery at the Isabela Substatin in January The nursery cnsisted f twenty 5-m rws spaced 0.76 cm apart. Twenty-five seeds were planted in each rw. The previusly described agrnmic practices were used t manage this nursery. ne hundred ears were selected frm this nursery based n the agrnmic traits f the female parent and seed quality. The 00 half-sib families were evaluated in a replicated trial planted at the Isabela Substatin in ctber 2004 (Table 2). The experimental design and mst agrnmic practices were the same as fr the trial planted in Nvember In this trial, hwever, an additinal 500 kg/ha f granular fertilizer was applied shrtly befre flwering. Ear width was estimated based n a randm sample f five ears frm each rw. Btanical Descriptin Mayrbela 05 has a yellw flint seed type with a mean 00 seed weight f 30 g. Plants flwered (silked) at apprximately 55 days after planting (DAP) and reached harvest maturity at apprximately 95 DAP. was m in 2002 and 3 m in 2004 (Tables and 2). was.29 m in 2002 and m in Mst plants prduced ne ear per plant. Ear length averaged 8.7 cm in 2002 and 4.6 cm in 2004 whereas mean ear width was cm in Tlerance t Pests and Diseases Sme leaf damage caused by Spdptera frugiperda (Smith) was bserved during vegetative develpment, but this damage was cntrlled by a single applicatin f insecticide. The 20 half-sib families selected after the secnd cycle f mass selectin had mean ear damage scres < 3, which is cnsidered t be highly resistant (Table 2). N significant damage caused by disease was bserved in the 2002 and 2004 plantings. Prductin Mean seed yield f the 20 half-sib families selected after the first cycle f mass selectin was 5,457 kg/ha, and 6,494 kg/ha after the secnd cycle f mass selectin (Tables and 2). Sme f the differences in mean seed yield may be attributed t higher rates f fertilizatin used fr the 2004 planting. In the 990s, the natinal average seed yield f maize in the U.S. was 7,839 kg/ha (Tiefenthaler et al., 2003), and 2,550 kg/ha in Brazil (Mrris and López-Pereira, 999). Uses Mayrbela 05 can be harvested near physilgical maturity fr the fresh market. The cultivar has an intense yellw seed clr which is a preferred trait in lcal markets. Because Mayrbela 05 prduces tall plants (2.5 m) that have a lw incidence f ldging,

3 TABLE. Perfrmance f half-sib families f 'Mayrbela 05' maize after the first cycle f mass selectin planted at the Isabela Substatin Nvember in Half-sib families Cultivar mean LSD (5) Seed yield (kg/ha) ppulatin ('000 plants/ ha) Ldging (n. plants) length (cm) Mean n. ears per plant Mean seed quality scre ( t 9) Seed quality scres rated n a t 9 scale where = high cmmercial value and 9 = n cmmercial value. ' Insect damage scres ears evaluated using a t 0 scale where t 3 = very resistant, 4 t 6 = mderate resistance and 6 = = susceptible. damage scre 2 ( t 0) d? c' " a r8 < tr C 22 p C * 5- a i W t S t

4 TABLE 2. Perfrmance f half sib families f 'Mayrbela 05' maize after the secnd cycle f mass selectin planted at the Isabela Substatin ctber in t S Half-sib family Cultivar mean LSD (5) Seed yield (kg/ha) ppulatin ('000 plants/ha) Ldging (n. plants) Mean ear length (cm) Mean ear width (cm) Mean n. ears per plant Mean seed quality scre ( t 9) damage scre 2 ( t 0) Seed quality scres rated n a t 9 scale where = high cmmercial value and 9 = n cmmercial value. 2 Insect damage scres ears evaluated using a t 0 scale where t 3 = very resistant, 4 t 6 = mderate resistance and 6 = susceptible p tsa 8 tt"

5 J. Agrie. Univ. P.R. VL. 90, N. 3-4, JULY-CTBER the cultivar may be used t prduce silage. The seed f Mayrbela 05 can als be harvested dry and used as a feed grain fr livestck. Availability f Seed The Agricultural Experiment Statin seed prgram at the Isabela Substatin will maintain fundatin seed stcks f Mayrbela 05. Recurrent selectin based n the perfrmance f half-sib families will be used t cntinue t select Mayrbela 05 fr increased seed yield and reduced insect damage n ears. LITERATURE CITED Fuentes, M., A. Pantja, A. Stmayr and J. Beaver, 998. Selección recurrente recíprca: tlerancia al ataque del gusan de la mazrca y el cgller (Lepidptera: Nctuidae). Agrnmía Mesamericana 9: Gdman, M. M. and W. L. Brwn, 988. Races f crn, pp In: G. F Sprague and J. W. Dudley (eds.), Crn and Crn Imprvement. 3rd ed. Agrn. Mngraph 8. ASA, CSSA, SSSA, Madisn, WI. Mll, R. H., W. S. Salhuana and H. F Rbinsn, 962. Hetersis and genetic diversity in cultivar crsses f maize. Crp Sci. 2: Mrris, M. L. and M. A. López-Pereira, 999. Impacts f maize breeding research in Latin America, Centr Internacinal de Mejramient de Maíz y Trig (CIMMYT), Mexic City, Mexic. Pllak, L. M., S. Trres-Cardna and A. Stmayr-Rís, 99. Evaluatin f hetertic patterns amng Caribbean and trpical X temperate maize ppulatins. Crp Sci. 3: Rbbins, W. A. and H. L. Warren, 993. Inheritance f resistance t Exserhilum turcicum in PI 20935, Mayrbela cultivar f maize. Mayólica 38: Tiefenthaler, A. E., I. L. Gdman and W. F Tracy, Vegetable and crn yields in the United States, 900-present. HrtSci. 38:-3. U.S. Census Bureau, U.S. Trade with Puert Ric and U.S. Pssessins during Widstrm, N. W., 967. An evaluatin f methds fr measuring crn earwrm injury. J. Ecn. Entmlgy 60: