5 | CONCLUSION
The study showed that the negative effects of the stress around flowering persisted in the kernel. In field, the accelerated leaf senescence and decreased net photosynthesis rate was observed. Although the supply of source was sufficient in vitro cultured in the chamber, the effect of stresses imposed around flowering on kernel weight was inevitable. The kernel weight reduction mainly resulted from decreasing enzyme activities related to starch synthesis, which further reduced grain filling rate. It is necessary to further investigate the effect of the early stresses on kernel through the view of key proteins and genes. This information is important for breeding and selecting stress tolerant maize hybrids.