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Acta Agronomica Sinica ›› 2022, Vol. 48 ›› Issue (2): 529-537.doi: 10.3724/SP.J.1006.2022.14024

• RESEARCH NOTES • Previous Articles    

Effects of sink-limiting treatments on leaf carbon metabolism in soybean

ZHANG Guo-Wei1(), LI Kai2, LI Si-Jia1, WANG Xiao-Jing1, YANG Chang-Qin1, LIU Rui-Xian1,*()   

  1. 1Institute of Industrial Crops, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, Jiangsu, China
    2Institute of Soybean, Nanjing Agricultural University / Key Laboratory of Soybean Biology and Genetic Breeding, Ministry of Agriculture and Rural Affairs / National Center for Soybean Improvement/State Key Laboratory of Crop Genetics & Germplasm Innovation, Nanjing 210095, Jiangsu, China;
  • Received:2021-02-07 Accepted:2021-07-12 Online:2022-02-12 Published:2021-08-09
  • Contact: LIU Rui-Xian E-mail:zgw_0721@163.com;liuruixian2008@163.com
  • Supported by:
    This study was supported by the National Key Research and Development Program of China(2018YFD0201000);the China Agriculture Research System(CARS-04);the Jiangsu Agricultural Industry Technology System(JATS[2020]152)

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Abstract:

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 (Pn) in a short time after treatment, but did not affect the initial carboxylation rate (ɑ), and the decrease of Pn 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 (a), 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.

Key words: soybean, carbon metabolism, source-sink relationship, sink-limiting treatment, photosynthetic performance

Fig. 1

Effects of sink-limiting treatment on leaf numbers in soybean T1: remove all pods; T2: remove half of pods; T3: seed-injured treatment; T4: the control. Bars superscripted by different lowercase letters are significantly different at P < 0.05."

Table 1

Effects of sink-limiting treatment on chlorophyll content in soybean leaves"

处理后天数
Days after treatment		 年份
Year		 处理
Treatment		 Chl a Chl b Car Chl a+b Chl a/b
7 d 2019 T1 1.82 a 0.45 a 0.46 a 2.27 a 4.02 b
T2 1.75 ab 0.42 ab 0.45 a 2.17 ab 4.16 a
T3 1.78 a 0.44 ab 0.45 a 2.22 a 4.06 b
T4 1.70 b 0.41 b 0.41 b 2.11 b 4.13 a
2020 T1 1.68 ab 0.43 ab 0.45 a 2.11 a 3.91 b
T2 1.71 a 0.41 bc 0.46 a 2.12 a 4.17 a
T3 1.69 ab 0.46 a 0.46 a 2.15 a 3.67 c
T4 1.61 b 0.38 c 0.42 b 1.99 b 4.24 a
14 d 2019 T1 1.80 a 0.44 a 0.46 a 2.24 a 4.12 b
T2 1.75 b 0.42 ab 0.45 a 2.17 b 4.14 ab
T3 1.77 b 0.43 a 0.45 a 2.19 b 4.16 a
T4 1.61 c 0.39 b 0.42 b 2.00 c 4.12 b
2020 T1 1.76 a 0.43 a 0.45 a 2.19 a 4.09 a
T2 1.77 a 0.44 a 0.46 a 2.21 a 4.02 ab
T3 1.79 a 0.45 a 0.44 a 2.24 a 3.98 ab
T4 1.56 b 0.40 b 0.41 b 1.96 b 3.90 b
35 d 2019 T1 1.58 a 0.41 a 0.41 a 1.99 a 3.90 a
T2 1.48 b 0.39 a 0.36 b 1.87 b 3.79 b
T3 1.58 a 0.40 a 0.41 a 1.98 a 3.93 a
T4 1.12 c 0.32 b 0.32 c 1.44 c 3.51 c
2020 T1 1.62 a 0.42 a 0.43 a 2.04 a 3.86 b
T2 1.36 b 0.36 b 0.32 c 1.72 b 3.78 c
T3 1.63 a 0.41 a 0.39 b 2.04 a 3.98 a
T4 1.06 c 0.31 c 0.29 d 1.37 c 3.42 d

Fig. 2

Effects of sink-limiting treatment on gas exchange parameters of leaves in soybean in 2020 Bars superscripted by different lowercase letters are significantly different at P < 0.05. Treatments are the same as those as given in Fig. 1."

Table 2

Effects of sink-limiting treatment on chlorophyll content of leaves in soybean in 2020"

处理
Treatment		 7 d 35 d
a Pmax Cisat Γ Rp a Pmax Cisat Γ Rp
T1 0.1866 a 46.33 c 1522.16 b 64.33 a 10.78 a 0.1314 a 41.83 a 1522.65 a 71.95 c 8.4828 a
T2 0.1902 a 50.33 b 1640.36 a 64.42 a 11.10 a 0.0942 b 33.51 b 1018.47 b 78.12 b 6.3825 b
T3 0.1844 a 47.67 c 1661.21 a 65.12 a 11.13 a 0.1288 a 38.38 a 1499.22 a 69.33 c 8.0170 a
T4 0.1855 a 53.12 a 1600.62 a 62.14 b 8.85 b 0.0436 c 26.09 c 998.73 b 118.36 a 4.9093 c

Fig. 3

Effects of sink-limiting treatment on enzymes activities of carbon metabolism in soybean leaves in 2020 Bars superscripted by different lowercase letters are significantly different at P < 0.05. Treatments are the same as those as given in Fig. 1."

Fig. 4

Effects of sink-limiting treatment on soluble sugar, starch, fructose, and sucrose contents in soybean leaves in 2020 Bars superscripted by different lowercase letters are significantly different at P < 0.05. Treatments are the same as those as given in Fig. 1."

Table 3

Effects of sink-limiting treatment on dry matter accumulation and partition in soybean (g plant-1)"

年份
Year		 处理
Treatment		 茎
Stem		 叶柄
Petiole		 叶
Leaf		 籽粒
Seed		 荚皮
Pod shells		 总干重
Total dry weight
2019 T1 16.90 a 8.98 a 15.87 a 0 c 0 d 41.8 d
T2 15.63 b 8.26 b 14.93 b 12.15 b 4.78 c 55.8 b
T3 16.71 a 8.72 ab 15.72 a 0 c 5.58 b 46.7 c
T4 14.18 c 6.06 c 13.03 c 23.45 a 8.61 a 65.3 a
2020 T1 16.27 a 7.93 a 14.93 a 0 c 0 d 39.1 d
T2 14.54 b 7.26 b 14.01 b 11.47 b 4.57 c 51.9 b
T3 16.23 a 8.01 a 15.08 a 0 c 5.71 b 45.0 c
T4 13.38 c 6.34 c 11.98 c 22.18 a 8.48 a 62.4 a
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