分蘖期干旱胁迫对寒地粳稻光合特性及产量形成的影响

Effect of Drought Stress at Tillering Stage on Photosynthetic Characteristics and Yield Formation of Cold-region Rice

为了探讨分蘖期干旱胁迫对寒地粳稻产量形成的影响机理及其耐旱机制,以东农425(耐旱型)和松粳6号(干旱敏感型)为试验材料,通过盆栽方式于分蘖期控制土壤水势至0 k Pa(对照)、-10 k Pa(轻度干旱)、-25 k Pa(中度干旱)、-40 k Pa(重度干旱),依次记为A0、A1、A2、A3。处理21 d后复水,研究分蘖期不同程度干旱胁迫对寒地粳稻叶面积、光合特性、叶绿素总含量、产量及产量构成因素的影响。结果表明,分蘖期干旱胁迫导致叶面积减小、功能叶片净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)和胞间CO2浓度(Ci)均随土壤水势降低而下降。同时,干旱处理期间寒地粳稻功能叶片叶绿素总含量、叶绿素a/b值均随干旱胁迫程度增加而下降,但类胡萝卜素含量的变化却与其相反。干旱胁迫下寒地粳稻产量显著下降,且下降幅度随土壤水势降低而逐渐增大。有效穗数和穗粒数大量降低造成产量显著下降,说明分蘖期干旱胁迫造成减产的主要原因是低土壤水势造成了寒地粳稻库容量或单位面积颖花量的大量降低。与A0(对照)相比,A1、A2和A3下松粳6号产量降幅分别为13.87%、20.87%和32.51%;而东农425分别为10.58%、15.21%和25.52%,均显著低于松粳6号,且耐旱型品种东农425始终保持较高光合生长能力。本研究结果为寒地粳稻抗旱节水栽培技术措施的制定提供了理论依据。

In order to investigate the mechanismof drought stress and drought tolerance at tillering stage on yield formation of cold-region rice, Songjing 6（drought-sensitive） and Dongnong 425（Drought-tolerant） were selected as test materials. Drought stress was started with the tillering stage, finished with 21 days after treatment, and the soil water potential was 0 kPa（control）, - 10 kPa（mild drought）, -25 kPa（moderate drought）, -40 kPa（sever drought）, they were respectively recorded as A0, A1, A2, A3. The effects of different drought stress on photosynthetic characteristics, chlorophyll total content, leaf area, yield and its components of cold-region rice were investigated. The results showed that the leaf area, Pn, Tr, Gs and Ci all decreased with the soil water potential. Besides, during the period of drought treatment the content of chlorophyll, chlorophyll a/b ratio all decreased with the soil water potential, but the carotenoids was opposite. The yield of cold-region rice decreased significantly under drought stress, and the amplitude was opposite, of which the main reason is the significantly cut of effective panicle and spikelets numbers. It indicated that the cut of yield in cold-region rice was because the significant reduction of storage capacity and spikelets per unit area caused by low soil water potential. At the same time, compared with A0 the drop of yield in A1, A2 and A3 of Songjing 6 were 13.87% ,20. 87% and 32.51% respectively; while those of Dongnong 425 were 10.58% , 15.21% and 25.52%, which were significantly lower than Songjing 6. Moreover,drought-tolerant varieties Dongnong 425 remained stronger growth and photosynthetic capacity. Therefore, the test was aimed to find out the mechanism of yield formation of cold-region rice under drought stress and enrich the physiological basis of drought resistance of cold- region rice. In order to provide theoretical basis for the establishment of water saving cultivation techniques of cold-region rice.