Root System Morphological and Physiological Characteristics of Indica-japonica Hybrid Rice of Yongyou Series

Abstract

A field experiment was conducted to compare the root system morphological and physiological characteristics of four types of rice populations including indica-japonica hybrid rice of Yongyou series(A), japonica hybrid rice(B), conventional japonica rice(C), and indica hybrid rice(D) under high-yielding cultivation condition in the rice-wheat cropping system. Results were as follows:(1) The root dry weight, aboveground dry weight, number of root tips, root length, root surface area, root-shoot ratio and root volume of A were obviously higher than those of B, C, and D at the middle and late growth stage.(2) The proportion of number, length, surface area and volume of the adventitious roots(root diameter 0.3 mm) to the whole roots of A were higher than those of B and C, while lower than those of D at heading; the proportion of number, length, surface area and volume of the fine branches(root diameter ≤ 0.1 mm) and coarse branches(0.1 mm root diameter ≤ 0.3 mm) to total roots of A were higher than those of D, while lower than those of B and C at heading. The proportions of root weight in 0–5 cm, 5–10 cm, and 10–15 cm soil layers to total roots weight of A were higher than those of B and C, while lower than those of D; however, the proportions of root weight in 15–25 cm, 25–35 cm, 35–45 cm, and 45–55 cm soil layers to the total root weight where lower than those of B and C, while higher than these of D at heading.(3) The total absorbing surface area, active absorbing surface area, bleeding intensity, root oxidation activity, and root reducing activity of A were higher than those of B, C, and D. Compared with B, C, and D, the indica-japonica hybrid rice of Yongyou series had significant advantage in root-shoot coordination level, root amount, branch structure, root distribution in soil and biological activity in the middle and late growth stage. This peculiarity of A provides an important guarantee to realize the super-high-yield.