| In order to research the effects of rice husk biochar and humic acid application on rice growth physiology, yield and cadmium content of rice grain under cadmium contaminated soil, both pot and field experiments through random block design were conducted. Hybrid rice Zhuliangyou 819 was used as experimental material, ten different treatments of rice husk biochar and humic acid combination for control, A (rice husk biochar 1000kg/hm~2+ humic acid 450kg/hm~2), B (rice husk biochar 2000kg/hm~2+humic acid 450kg/hm~2), C (rice husk biochar 4000kg/hm+ humic acid 450kg/hm), D (rice husk biochar 1000kg/hm+ humic acid 600kg/hm~2), E (rice husk biochar 2000kg/hm~2+humic acid 600kg/hm~2), F (rice husk biochar 4000kg/hm~2+humic acid 600kg/hm~2), G (rice husk biochar 1000kg/hm~2+ humic acid 750kg/hm~2), H (rice husk biochar 2000kg/hm~2+humic acid 750kg/hm~2), I (rice husk biochar 4000kg/hm~2+humic acid 750kg/hm~2) were set under high-cadmium soil of the field experiment. Conventional rice Xiangzhaoxian 45 were used as experimental materials, four teatments, including control, rice husk biochar, humic acid and (rice husk biochar+ humic acid) were set under both no-cadmium treatment soil and high-cadmium treatment soil of the pot experiment. The samples for measurment relative physiological index were collected at the heading stage, filling stage and maturity stage of rice. Main results were as follows.1. Rice husk biochar and humic acid improved the rice agronomic characters. Rice plant height and yield componets were improved by both rice husk biochar and humic acid. The maximum of rice plant height showed up in treatment F of field experiment. The plant height of (rice husk biochar+humic acid) treatment was the tallest among 4 treatments of pot experiment, and plant height under no-cadmium and high-cadmium were increased by 8.85% and 7.25%, respectively. In the field experiment, the maximum of the number of grain per panicle, setting percentage and thousand kernel weight were all reached in treatment F, were increased by 17.46%,17.74% and 11.99% comparing to control; in pot experiment, the maximum of number of grain per panicle, setting percentage and thousand kernel weight were all reached in treatment (rice husk biochar+humic acid), were increased by 4.60%, 7.09% and 8.22%comparing to control.2. Rice husk biochar and humic acid increased rice photosynthetic parameters, as well as improved rice yield and its quality. The leaf net photosynthetic rate at different development stages and average yield of the pot experiment treated with (rice husk biochar+ humic acid) were largely increased more than those treated with rice husk biochar and humic acid. Average yield was increased by 12.76% in treatment F of the field experiment more than that in control. In pot experiment, the leaf net photosynthetic rate of treatment (rice husk biochar+humic acid) in high cadmium soil increased by 12.46% and 18.19% comparing to control.3. Rice resistance was increased by rice husk biochar and humic acid. The leaf superoxide dismutase activity, peroxidase activity and catalase activity at both heading stage and filling stage were increased through adding rice husk biochar and humic acid. The highest activities of three enzymes were all in the (rice husk biochar+humic acid) treatment under field experiment.4. Rice husk biochar and humic acid were lowed cadmium accumilation of rice grain. Grain cadmium contents of Zhuliangyou 819 of rice husk biocar and humic acid combination treatments under field experiment were significantly lower than that of control, and grain cadmium content of F treatment was lower than that of control by 54.64%?5. There were significantly interaction effects on rice physiology between rice husk biochar and humic acid. The effects of rice husk carbon and humic acid on superoxide dismutase (SOD) activity, catalase activity, peroxidase activity of Xiangzhaoxian 45 at heading stage and grain filling stage of were carried out fitting the general linear model of variance analysis using SPSS22.0 and generated interaction diagram which indicated significant interaction effects of rice husk carbon and humic acid on rice leaf physiology. |
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