The influence of accelerated ageing and stimulative concentrations of 2,4-D on maize (Zea mays L.) seeds. [Doctoral dissertation] | Uticaj ubrzanog starenja i stimulativnih koncentracija 2,4-D na seme kukuruza (Zea mays L.). Doktorska disertacija

The loss of seed vitality occurs during prolonged storage, and a small amount of seedlings are of low vitality, while the share of deformed seedlings increases. The differences in seed vitality of maize hybrids and their parental inbreeds are determined by accelerated ageing treatment (simulating prolonged storage conditions) and analysis of content in constitutive and antioxidant substances. Besides, vitality of seedlings, originated from aged seeds, can be restored by the low concentrations of 2,4-D (2,4-dichlorophenoxyacetic acid) application. Age-induced modifications depend on a genotype: dent maize seeds characterize fragmentation of nonthiolic proteins and coagulation of thiolics, while surgery seeds characterize nonenzymatic glycation of proteins and phenolics, with disulphide dethiolation. Thermodynamical parameter of different enthalpy, i.e. the value of 0J could be a distinction between reversible and irreversible injures in seed. As the glutathione represent the most significant antioxidant in seeds its higher amount is a guarantee of extended longevity. The weak growth of seedlings originated from aged seeds, i.e. a lower fresh mass and length of roots and shoots are consequences of the uneven distribution of mass (including the content of nitrogen, phosphorus and sulphur) and water, with their retention in the seed rest, and it is underlined in sugary genotypes. Thermodynamically, weaker growth can be described as decrease in overall energy potential. The positive influence of 2,4-D low concentrations on seeds, exposed to accelerated ageing is observed in: rising of germinable maize seeds, fresh mass and length increasing of root and shoot, intensification of dry substance hydrolysis and biosynthesis. The growth stimulation was performed via the increase of redox and energy potential of seedlings. The concentration of 5x10E-9 mol/L showed the highest stimulation of germination, while the concentration of 5x10E-9 mol/L, i.e.10E-6 mol/L expressed the highest growth stimulation in sweet, i.e. dent maize genotypes, respectively.