Photosynthesis and chlorophyll fluorescence of infertile and fertile stalks of paired near-isogenic lines in maize (Zea mays L.) under shade conditions

Abstract

The rainy season affects the development of maize in Liaoning Province in China. Continuous, rainy weather and scant sunlight result in poor pollination, bald tips, and in an abnormally high, barren stalk. Field studies were conducted at the kernel formation stage (3–11 d after silking). Paired, near-isogenic lines of nonbarren stalk (Shennong 98B) and barren stalk (Shennong 98A) were exposed to 38, 60, and 75% shading to investigate changes in photosynthesis and chlorophyll (Chl) fluorescence characteristics under different light intensities. Net photosynthetic rate (P N), leaf maximum photochemical efficiency of PSII (Fv/Fm), photochemical quenching of Chl fluorescence (qP), and actual photochemical efficiency of PSII (ΦPSII) of Shennong 98B were always higher than those of Shennong 98A under natural light, contrary to nonphotochemical quenching (NPQ). Fv/Fm, ΦPSII, and qP increased, while P N and electron transport rate (ETR) decreased after shading, and this was aggravated with increasing shade intensity. P N, qP, ΦPSII, and ETR were lower than the values in natural light condition after seven days of shading. NPQ, Fv/Fm, ΦPSII, qP, and ETR recovered, when shading was removed. The P N of two inbred lines returned soon to the control levels after 38% shade. Under shade and natural light conditions, the P N and Chl fluorescence characteristics of Shennong 98A were both lower than those of Shennong 98B. We suggest that a poor adaptability to low light is an important physiological reason for inducing barren stalk in low light-sensitive maize.