At the beginning of silking, maize production began to form, but leaves started senescence and photosynthetic capacity decreased at this time, all of those severely restricted the formation of the production. In order to study the effects of exogenous substances on the process of leaf senescence, 40 mg. L-1 DCPTA and 20 mg. L-1 CCC were mixed in the research. When the maize grew to the six expanded leaves stage, 10 mL compound mixtures （TR） were sprayed on both sides of leaves for per plant, and the control was treated with water （CK）. Three plants were selected randomly for determination of physiological index at 10, 20, 30, 40 and 50 days after silking. The results showed that TR could increase the chlorophyll content significantly, FvFm, Fv/F0 and Y（Ⅱ） values of TR were higher than those of CK while F0 values were opposite. Compared with CK, TR increased SOD and POD activities and soluble protein content, and reduced MDA content. Correlation analysis showed that chlorophyll content had negative correlation with F0, and MDA content had negative correlation with other indexes. Compared with CK, TR reduced the negative correlation effect between chlorophyll content and MDA, increased the positive correlation effect between chlorophyll content and Fv/Fm, SOD, PODI and soluble protein. The study provided theoretical and experimental evidence for the application of the compound mixtures of DCPTA and CCC to the production.
Wang Yong-chaoGu Wan-rongYe Le-fuSun YangLi Li-jieZhang HeLi JingWei Shi
DCPTA （2-diethylaminoethyl-3, 4-dichlorophenylether） is a new plant regulator which can be used to regulate growth and development for crops. Experiments on maize seedlings were conducted in the growth chamber to study the effects of foliar applied DCPTA. The plant pots were placed in a completely randomized design with three replicates. The maize seedlings were treated with 0 mg·L-1 （control）, 20 mg·L-1 and 40 mg·L-1 DCPTA solution. The effects of DCPTA on the photosynthetic characteristics （photosynthesis, stomata conductance, intercellular CO2, and transpiration rate）, related physiological characteristics （contents of soluble sugar and starch）, chlorophyll fluorescence parameters （Fo, Fro, Fv/Fm, Fv/Fo, qP, and qN） and the weight of dry matter in maize seedling were studied. The results showed that DCPTA enhanced photosynthesis of maize seedling. In general, photosynthetic rate in leaves was significantly promoted through spraying DCPTA solution, and 40 rag＂ L~ DCPTA was found to be the best concentration for maize. The relationship between stomata conductance and transpiration rate in maize leaves could be described as linear. With regard to the chlorophyll fluorescence parameters, our fmdings showed that 40 mg·L-1 DCPTA in maize seedling caused an increase in Fm, Fv/Fm, Fm/Fo, qP and a decrease in Fo and qN at some time points checked. It is suggested that DCPTA increased photosynthetic rate by raising both the content of chlorophyll and activities of PSII and the contents of sugar and starch. Compared with the control, the treated maize seedling caused an increase in plant height, root length, shoot dry mass, root dry mass, or the total （root plus shoot） dry mass.
Gu Wan-rongMeng YaoZhang Jun-baoJi BiaoWang Yong-chaoLi JingWei Shi
