DYNAMICS OF NUTRIENT REMOBILIZATION FROM SEED OF WHEAT GENOTYPES DURING IMBIBITION, GERMINATION AND EARLY SEEDLING GROWTH

The changes in nutrient content of grain tissues and seedling parts of two wheat genotypes (Triticum aestivum L., Excalibur and Janz) with l ow or high seed Zn content were followed from imbibition to early seed ling development (12 days). The grains were separated into seed coat, endosperm and embryo, while the seedlings were separated into roots an d shoots. The dry weight of the seed coat did not change throughout th e experimental period, whereas the endosperm weight declined rapidly f rom day 4 onward. The weight of embryo did not show any difference bet ween and within cultivars. About a half of seed Zn was remobilised int o shoot and roots during 12 days of growth, regardless of the initial seed Zn content in both genotypes. The seed coat contained 55-77% of t he total seed nutrients in the two wheat genotypes, except in the case of S (around 40%). Manganese, Fe, Ca, K, and P were remobilised effec tively from the seed coat as well as from the endosperm, while remobil isation of Zn and Cu was relatively less from the seed coat than from the endosperm. After 10 days of growth, all nutrients monitored were c ompletely remobilised from the endosperm. Remobilised K was directed p rimarily into shoots; an increase in K content in shoots was relativel y higher than the accumulation of dry matter, with a consequent increa se in K concentration in shoot tissue. The remobilisation of some nutr ients leg. Fe, Ca and Zn) from various grain tissues during inbibition , germination and early growth is different from the remobilisation in more mature plants.