| To investigate the effects of elevated ozone concentration ([O3]) on root growth, biomass production and nutrient (N, P, K) absorption and utilization of rice, we conducted an experiment for the first time in the world with using Free Air ozone Concentration Enrichment (FACE) system at Xiaoji town, Jiangdu County, Jiangsu Province, China (119°42′0″E , 32°35′5″N). Four rice varieties: Wuyunjing21 (conventional Japonica cultivar), Yangdao6 (conventional indica cultivar), Shanyou63 (three-line hybrid rice cultivar) and Liangyoupeijiu (two line hybrid rice cultivar), were grown at ambient and elevated (target at 50% above ambient) [O3]. Main results are as follows:1. With the exception of adventitious root length per hill at heading, elevated [O3] slightly reduced root dry weight per hill, adventitious root length per hill, roots volume per hill and adventitious root number per hill at tillering, jointing, heading, and maturity stage, but the effects were not statistically significant except adventitious root number per hill at tillering. On average, the diameter per adventitious root was smaller under elevated [O3] by 1.7%, 6.5% and 2.5% at tillering, jointing and heading, respectively. The effect of elevated [O3] was significant at jointing and heading stage. There was no significant interaction between O3 and varietyies for the above root morphological characteristics. 2. Elevated [O3] slightly increased the total absorption area and active absorption area per unit dry weight of root at tillering, jointing, heading, but the effects were not statiscally significant except the total absorption area per unit dry weight of root at tillering stage. There was no significant effect by Elevated [O3] on the amount ofα-NA per unit dry weight of root at tillering and jointing stage, but it was slightly increased by 16.6% at heading stage. Elevated [O3] also has no significant effect on the total absorption area per hill, the active absorption area per hill, and the amount ofα-NA per hill at different stages. There was significant interaction between O3 and varieties for the total absorption area per unit dry weight of root at tillering and the active absorption area per unit dry weight of root at tillering and jointing, but not for the other root physiological characteristics.3. On average, elevated [O3] slightly reduced the total matter accumulation of rice by 9.0%, 6.0%, 11.1% and 13.2% at tillering, jointing, heading, and maturity, respectively. The effect of elevated [O3] was significant jointing, heading, and maturity stage. There was significant interaction between O3 and varietyies at heading, but not at other stages.4. Elevated [O3] slightly increased the nitrogen (N) content at tillering, jointing, heading and maturity stage by 1.0%, 4.4%, 6.3% and 3.5%, respectively, but the effects were not statistically significant except at heading stage. Elevated [O3] slightly increased the N accumulation at tillering, jointing, heading and maturity stage by 8.0%, 1.5%, 5.4% and 9.9%, respectively, but the effects were not statistically significant except at maturity stage. There was no significant effect on N allocation in leaves, stem-sheath, panicle and roots. Mostly there was no interaction between O3 and varieties for the forenamed characteristics.5. There was no significant effect on phosphorus (P) content at tilling, jointing, heading and mature stage in rice plant. Elevated [O3] slightly reduced P accumulation by 6.6%, 5.4%, 9.0% and 13.2% at different stages respectively, but the effects were not statistically significant except at heading and mature stage. There was no effect on the distribution ratio of P in leaves, stem-sheath, panicle and roots except in stem-sheath at jointing. Mostly there was no significant interaction between O3 and varieties for the forenamed characteristics.6. Elevated [O3] slightly increased the potassium (K) content at tilling, jointing, heading and mature stage by 12.1%, 9.1%, 8.2% and 9.6% in rice plant, but the effects were not statistically significant. With the exception of the distribution ratios in leaves and stem-sheath at maturity stage, elevated ozone had no significant effect on the accumulation of Kand the distribution ratio of K in different organs at different stages. There was no significant interaction between O3 and varietyies for the forenamed characteristics.
|
PDF Full Text Request