Date Published: April 18, 2019
Publisher: Public Library of Science
Author(s): Chang Tian, Jichang Han, Juan Li, Guo Zhen, Yangyang Liu, Yangjie Lu, Yike Wang, Yang Wang, Yuan Huang.
To analyze three row orientations (south-north, east-west, southwestern 20°) and two row spacings (‘65 + 65’, ‘160 + 40’), we investigated the effect of row orientation and planting pattern on photosynthetic performance, physiological and biochemical indicators related to the aging of leaves. Results revealed that during maturity stage, in north-south and east-west, the initial fluorescence (Fo) at ‘65 + 65’ were higher than those under‘160 + 40’; the maximum quantum yield of PS2 photochemistry(ΦP0), basal quantum yield of non-photochemical processes in PS2(ΦN0)of the lower leaves and photosynthetic rate of the upper and ear leaves under‘160 + 40’were higher than those under‘65 + 65’. The polyphenoloxidase (POD) activities of leaves at different positions under ‘160 + 40’ were higher than that under‘65 + 65’, while the malondialdehyde (MDA) content was lower. The photosynthesis rate, superoxide dismutase (SOD) and catalase (CAT) activity of leaves at different positions under southwestern 20° ‘160 + 40’ were higher than others. Whilst MDA content ‘160 + 40’ were lower. Therefore, in De Hui City, Jilin Province, southwestern 20° ‘160 + 40’ delayed leaf senescence at the late stage of growth of maize, as well as the effect of increasing maize yield was most obvious.
Maize (Zea mays L.) has higher yields than rice and wheat. Therefore, maize has spread over China’s most area and become one of China’s major corps. To increase the production of maize, numerous experiments shave been done. Since 1988, Lu et al. and Duan et al. have proved that premature leaf function could largely affect the seed setting rate and further decide the grain yield; Later, Davide, Ma and Dwyer demonstrated that premature leaf senescence, reduced green leaf area and shortened photosynthetic time would severely damage the grain yield. So it’s well believed that keeping corps green and prolonging the photosynthetic time can improve the photosynthetic rate after anthesis, and thus significantly increase the grain yield. In 1986, Gentinetta and Brodbeck achieved a significant increase in yield, with an inbred maize which can maintain its greenness well. In 1993, Thomas and Smart showed that the yield would increase when the leaf aging rate decreased. The aforementioned results helped link the leaf aging speed to grain yield. Since seeds and vegetative organs grow simultaneously, how to prolong the leaf function and prevent the prematurely aging have become a major concern.
Maize is a high-light-efficiency C4 crop, whose canopy structure can be affected by the row configuration. Chlorophyll fluorescence is reddish-brown light, which is emitted by chlorophyll molecules with light stimulation under dark conditions. The fluorescence could be different depending on plant species and leaf age, which could predict carbon assimilation rate . The ΦP0 and ΦN0 of the ear leaf under different planting patterns showed gradually decreasing trend . The ΦP0 and ΦN0 of the upper leaves were lower, while the Fo was higher. Hence it’s confirmed that the upper leaves grew faster than lower ones.
In this paper, we experimentally demonstrated that SW 20 ‘160 + 40’ was the most favorable choice among all the planting patterns. SW 20 ‘160 + 40’ could help increase the photosynthetic rate of ear leaf; during the maturity stage, SW 20 ‘160 + 40’ could help remove the active oxygen free radicals in different parts of maize; in addition, SW 20 ‘160 + 40’ could also help prevent cells from damage, maintain the integrity of the structure, delay leaf senescence and increase maize yield. Therefore, in De Hui field site, SW 20 ‘160 + 40’ planting pattern significantly delayed leaf senescence in the late maize growth, and intensely increased the maize yield.