Competition among the Individual Plants within a Crop : 1 Interdependence between organs in different plant types

Abstract

The aim of the study was mainly to elucidate the difference in the top-root interdependence between different plant types (Erect and weep-type), from the population point of view. Materials used were Allium fistalosum L. for Erect-type and A. tuberosum Rotel for weep-type. 3 to 4 weeks after sowing, seedlings, about 10 cm in plant height, were planted in a wooden pots (25 cm × 25 cm × 25 cm) filled by the Hewitt's nutrient solution. As the treatments, 2 planting densities, 3 cm × 3 cm and 6 cm × 6 cm, and 2 nutrient levels, 1/2 and 1/5 Hewitt's solution, were employed in the experiment. Sampling was made 4 times at 2 week intervals during the experimental period after planting. Plant height, cumulative leaf blade length, maximum root length, cumulative root length, number of primary roots, top and root dry weight, and root activity were measured at every sampling occasions. As an index showing the root activity, α-Naphtylamine (α-NA) oxidizing activity in roots was ripplied. The results obtained were as follows; 1. Plant dry weight was affected more markedly by the planting density in E-type (A. fistalosum L.) over the period of experiment. In W-type (A. tuberosum Rotel), however, the nutrient level had more serious influence upon the plant growth in the latter stage of growth. 2. A high positive correlation between plant dry weight and root dry weight, cumulative root length, maximum root length were recognized in every treatment in both plant types. 3. The values of the T/R ratio in every plot was increased gradually in advance with growth in E-type (A. fistalosum L.), and was, on the contrary, decreased in W-type (A. tuberosum Rotel). 4. Calculated coefficient of allometric relative growth rate (α) was α>1 in E-type (A. fistalosum L.) and was α<1 in W-type (A. tuberosum Rotel). 5. α-NA oxidizing activity in roots decreascd in advance with growth in every treatment and it's value was higher in lower nutrient level and lower planting density.