Contribution of reserves to kernel weight and grain yield determination in maize: phenotypic and genotypic variation

Maize (Zea mays L.) kernel weight (KW) and grain yield depend on plant growth during active grain filling and reserves use. The objective of our study was to analyze the phenotypic and genotypic variation in these traits in a family of recombinant inbred lines (RIL). In two field experiments we measured plant grain yield (PGY) and its components (KW and kernel number per plant, KNP), biomass production per plant and per kernel during active grain filling, and apparent reserves use (ARU) per plant (ARUP, difference between PGY and plant biomass production during active grain filling) and per kernel (ARUK, difference between KW and plant biomass production per kernel during active grain filling). Heritability (h2) and phenotypic plasticity were computed for all traits. Large differences were always evident among genotypes, but phenotypic plasticity was (i) low for KW and plant biomass at R2 and physiological maturity; (ii) intermediate for KNP and PGY; and (iii) high for plant growth, plant growth per kernel after R2, and ARUs. Traits with highest h2 were KW (0.70), KNP (0.61), and ARUP (0.59). Final KW was related to plant growth per kernel (r2 = 0.64; P < 0.001) but not to ARUK, and ARUP was driven (r2 ≥ 0.49; P < 0.001) by KNP. Because of its positive relationship with KNP (main determinant of PGY), high h2 and high phenotypic plasticity, breeding must consider the increase in ARUP for improving grain yield, an objective that needs to be coupled with large reserves accumulation before silking to avoid the risk of lodging.Fil: D'andrea, Karina Elizabeth. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Producción Vegetal. Cátedra de Cerealicultura; ArgentinaFil: Piedra, Carlina Victoria. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Mandolino, Cecilia Ines. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Investigaciones y Transferencia del Noroeste de la Provincia de Buenos Aires. Universidad Nacional del Noroeste de la Provincia de Buenos Aires. Centro de Investigaciones y Transferencia del Noroeste de la Provincia de Buenos Aires; Argentina. Instituto Nacional de Tecnología Agropecuaria; ArgentinaFil: Bender, Ross. University of Illinois at Urbana; Estados UnidosFil: Cerri, Ana M.. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Producción Vegetal. Cátedra de Cerealicultura; ArgentinaFil: Cirilo, Alfredo Gabriel. Instituto Nacional de Tecnología Agropecuaria; ArgentinaFil: Otegui, Maria Elena. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentina. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Producción Vegetal. Cátedra de Cerealicultura; Argentin