减库对大豆叶片碳代谢的影响

Abstract

<p id="C3">Carbon metabolism is one of the most obvious physiological processes affected by source-sink relationship, which is closely related to plant growth and yield formation. The study of the effect of sink-limiting treatment on carbon metabolism of soybean leaf can provide a theoretical basis for understanding yield reduction mechanism caused by the imbalance of source-sink relationship. Taking early maturing soybean Sudou 13 as materials, pool experiments were carried out at the soybean experimental station of Jiangsu Academy of Agricultural Sciences in 2019 and 2020. The sink-limiting treatments (all pods removal, 1/2 pods removal, and all seed injury) were conducted at R4 stage, and intact (fully podded) plants were used as control. The results showed that sink-limiting treatments delayed leaf senescence and abscission and caused stay-green. Sink-limiting treatments inhibited the net photosynthetic rate (<italic>P</italic>_n) in a short time after treatment, but did not affect the initial carboxylation rate (ɑ), and the decrease of <italic>P</italic>_n was mainly restricted by stomata limitation. With the prolongation of the time after treatment, the inhibition effect on photosynthesis gradually weakened and turned into a promoting effect. At late growth stages, the stay-green syndrome leaves still maintain relatively higher initial carboxylation rate (<italic>a</italic>), sugar phosphate synthase (SPS), sucrose synthase (SuSy), acid invertase (SAI) activity, photosynthetic pigment, soluble sugar, starch, sucrose, and fructose content, which was beneficial to maintaining a relatively high photosynthetic performance. Sink-limiting treatments induced more photosynthetic products to be distributed to vegetative organs, and stimulated stems and leaves to be new sink organs in certain extent, which was beneficial to the output of photosynthetic products and maintained relatively high levels of carbon metabolism of leaves at late growth stages. The effects of removing all pods and seed injury treatments on delaying leaf senescence and abscission, reducing photosynthetic performance and carbon metabolism was significantly higher than those of removing 1/2 pod. In conclusion, sink-limiting under the same source condition could induce stay-green syndrome. The greater the degree of sink-limiting, the more severe the green retention. Sink-limiting treatment significantly affected the carbon metabolism of soybean plant, although it inhibited photosynthetic performance in a short period after treatment. It maintained higher photosynthetic and key enzyme activities of carbon metabolism at late growth stages, which was conducive to the synthesis of more carbohydrates and stimulated the stems, leaves, and petioles to transform into new sink organs to a certain extent.