| In order to study the cytoplasmic effects of male sterile wheat, male sterile lines of CHA (chemical hybridizing agent) and cytoplasmic K (Aegilops kotschyi), T (Triticum timopheevi), V (Aegilops ventricosa) types of male sterile wheat at different developmental stages were compared with their maintainer lines in the diurnal changes of photosynthetic and physiological parameters, comprising net photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (Tr), water use efficiency (WUE), photon flux density (PFD), intercellular CO2 concentration (Ci), atmospheric CO2 concentration (Ca), leaf temperature (Ti), atmospheric temperature (Ta), and stomatal limiting value (Ls). And these parameters may reflect the photosynthetic efficiency of the leaves and environmental adapting capability of the plant. The experiment was conducted to analyze the diurnal changes and the physiological mechanism of photosynthetic midday-depression, the response to male sterile cytoplasms of female parent genotypes and the differences of photosynthetic and physiological parameters of 4 male sterile lines and their maintainer lines, which can reflect differences of heredity of 4 male sterile cytoplasms under the same nuclear background and also exhibit differences of the effect of nuclear-cytoplasmic interaction. In addition, in order to study the effect factors of photosynthetic rate in male sterility lines of wheat, male sterile lines of CHA and cytoplasmic K, T, V types of male sterile wheat were compared with their maintainer lines in the dynamic changes of net photosynthetic rate (Pn) and relatively physiologic and environmental factors, which relationship between them were also analyzed. Follows are the major results:1. The curve of diurnal changes of Pn presented two peak values, with one peak at 10:00 higher than the other at 14:00. And the phenomenon of photosynthetic midday-depression of leaf happened at noon. The diurnal changes of Pn was positively correlated with Gs, Ci and negatively correlated with Ls, and the correlation coefficients were 0.8187*, 0.8136* and -0.8496* respectively. Accompanied by the decline of Gs, Ci and the raise of Ls, Pn declined distinctly in midday, which means the limitation of Pn by stomatal factor.2. Compared with their maintainer lines, CHA and K, T, V-male sterile lines had lower Pn values, decreasingly 0.88, 2.76, 3.30, and 2.04μmol CO2 m-2 s-1 respectively, indicating that the CHA and K, T, V-cytoplasm has negative effects on Pn with different extent, especially T and K-types.3. K, T, V cytoplasmic male sterile lines had lower WUE values than their maintainer lines, decreasingly 0.94-1.54μmol CO2 mmol-1 H2O and indicating that K, T, V-cytoplasm has significantly negative effects on WUE. Compared with the maintainer lines, CHA-sterile lines has no significant difference in WUE values, indicating chemical hybriding agent (BAU-9403) has no significantly negative effects on the water use efficiency of wheat flag leaf. The influences of damage caused by BAU-9403 were less than the negative effects of other male sterile cytoplasms.4. Pn and Gs, Tr had their most values at anthesis stage. The dynamic changes of Pn was positively correlated with Gs and Tr, and the correlation coefficients were 0.9305**-0.9677**, and 0.8081*-0.9068** respectively (r0.05=0.754, r0.01=0.874).5. Cytoplasms of K, T, V-type male sterile had negative effects on Pn, Gs and WUE of flag leaf with different extent. Tr of flag leaf depressed distinctly on account of CHA, but CHA had no significantly negative effects on the water use efficiency of wheat flag leaf. As to K, T, V, CHA-type male sterile wheat, the dynamic changes of Pn were the same with Gs and Ci, and were different from Ls, which indicated that the dynamic changes of Pn were restricted by the stomatal factor.6. Regression equation was significant (R2= 0.9658), which could preferably reflect the rules of dynamic changes of Pn and the other factors in K, T, V, CHA-type male sterile lines.7. Gs was the uppermost direct effect factor on Pn of K, T, V, and CHA types. And their direct path coefficients between Pn and Gs were 0.4943-0.6774, which were all significant. Furthermore, Tr, PFD, and Ta had significant effect on Pn of K, T-type male sterile lines, so did PFD and Ca on Pn of V-type male sterile lines. Chemical hybridizing agent led that Gs and Ci restricted the raise of Pn in CHA-type male sterile lines, which reflected Gs and Ci were the uppermost effect factors on Pn of CHA types.8. Moreover, the Pn value varied between genotypes of different female parents, Pn of Ji 5418 and its CMS lines showed significant or highly significant differences with that of Tai 911289, indicating that genotypes of female parents have different effects on different cytoplasms in Pn. This result also demonstrates the enormous potential for improving the photosynthetic capability in Ji 5418. Therefore, it is better to reduce the negative effects of male sterile cytoplasms on photosynthetic function of wheat by selecting preponderant recurrent parent to make backcross in a breeding project.9. The results of analysis of transmission electron microscope indicate that differences exist between K, V, T male sterile lines and their B lines in numbers of chloroplasts, numbers of granums, numbers of starch grains, the developmental degree of granums layers, and configuration of chloroplasts, which lead that the net photosynthetic rate of male sterile lines is lower than their B lines. |
