Eco-physiological Characteristics Related with Lodging Tolerance of Rice in Direct Sowing Cultivation. III. Relationship between the characteristics of root distribution in the soil and lodging tolerance.

Effect of Field Drainage on Root Lodging Tolerance in Direct-Sown Rice in Flooded Paddy Field

“…Seeds of both varieties were coated with coating materials including calcium peroxide to perform better germination and seedling establishment, and sown on the soil surface of field plots with unwoven cloth laid on May 12 and 13 in 30 cm-wide rows and with 7.5 cm intrarow spacing at the rate of 6 coated seeds per hill. The unwoven cloth was used for both varieties using the method described in a previous report (Terashima et al, 1995) : briefly, after rotary cultivation, the topsoil layer (from the soil surface to around 15 cm depth) was removed and a piece of unwoven cloth was laid on the exposed subsoil. The topsoil was then returned to the same position on the unwoven cloth and puddled after irrigation.…”

“…Pushing resistance per unit root dry weight was higher in rice grown in soil with higher bulk density and higher soil hardness than in soil with lower bulk density and lower soil hardness (Terashima et al, 1995). Differentiation of soil physical properties between topsoil and subsoil due to cultivation and puddling (Nakatsuka and Ishii, 1989), was considered to be related to the higher contribution of roots in the subsoil to anchoring, and in turn, to the superior anchoring ability of the varieties that extend more roots into the subsoil layer (Terashima et al, 1995).…”

“…Changes in the soil physical properties caused by field drainage may be another possible cause of better plant anchoring. Terashima et al (1995) pointed out that soil physical properties like soil hardness and bulk density significantly affect plant anchoring by roots.…”

“…Differentiation of soil physical properties between topsoil and subsoil due to cultivation and puddling (Nakatsuka and Ishii, 1989), was considered to be related to the higher contribution of roots in the subsoil to anchoring, and in turn, to the superior anchoring ability of the varieties that extend more roots into the subsoil layer (Terashima et al, 1995). Since field drainage affects the soil hardness of the topsoil layer (Tada et al, 1967a(Tada et al, , 1967bKohno, 1979), it is inferred that pushing resistance may be increased by field drainage through changes in soil physical properties like soil hardness.…”

Effects of elevated [CO2] on stem and root lodging among rice cultivars

“…In addition, while the stiff stems of modern cereal resist buckling, reducing incidence of stem lodging, they can transmit the forces generated by wind action into the ground-forces which can cause root lodging in which the root system rotates in the soil [14]. Studies confirmed that during rice growth, after stem lodging, root lodging is the next greatest lodging risk, and also proved that the larger roots system and thicker crown roots in subsoil were the very important characteristics for anti-lodging for root [15,16]. Although most studies approved that elevated [CO 2 ] promoted root growth, and increased the root volume, root biomass of rice [17,18], no study has examined the risk of root lodging under elevated [CO 2 ].…”