PHOSPHATE-COMPOUNDS IN GERMINATING MAIZE CARYOPSES AS RELATED TO HETEROSIS

The initial weight of maize (Zea mays L.) caryopsis was related to cha nges in the seedling weight and in the content of the intermediates of phosphate metabolism - phytin, inorganic phosphate, adenylic nucleoti des, and nucleic acids - studied during the early stages of germinatio n in two inbreds and their heterotic first generation hybrid (F1). The F1 hybrid was superior to the parental forms by the initial caryopsis and embryo weights, by the phytin and inorganic phosphate content, an d by the higher rates of biomass accumulation and phytin degradation i n the course of germination. In the 4-day-old F1 seedlings, the integr al parameters of energy metabolism (ATP content, the sum of adenylic n ucleotides, energy charge, and the reverse phosphate potential) were h igher than in the parental inbreds. The F2 hybrid was inferior to the inbreds and the F1 hybrid by most of these parameters; this phenomenon directly related to the decrease in the initial fresh weight of the c aryopsis and embryo. This evidence supports the physiological hypothes is of hybrid vigor advocated by Ashby.