Photosynthetic base of reduced grain yield by shading stress during the early reproductive stage of two wheat cultivars
Photosynthetic base of reduced grain yield by shading stress during the early reproductive stage of two wheat cultivars
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DOI：
10.1038/s41598-020-71268-4
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发表时间：
2020-09
影响因子：
4.6
通讯作者：
Hong Yang;B. Dong;Yakai Wang;Yunzhou Qiao;Chang-hai Shi;Lele Jin;Mengyu Liu
中科院分区：
文献类型：
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作者：
Hong Yang;B. Dong;Yakai Wang;Yunzhou Qiao;Chang-hai Shi;Lele Jin;Mengyu Liu
小麦幼孢子期是小麦籽粒形成对非生物胁迫最敏感的时期。YM期遮荫胁迫降低籽粒产量的主要原因是籽粒数减少。然而，籽粒数减少的光合作用基础尚不清楚。本研究以河农825、科农9204两个小麦品种为材料，在YM期分别进行了100%(对照)、40%(S1)、10%(S2)的自然光照处理，光照时间分别为1、3、5、7天。结果表明，合农825和克农9204的籽粒数分别比对照降低了33.3%和14.2-72.7%，− 分别降低了3.6%和33.3%。合农825和克农9204的叶片净光合速率分别下降4.5-93.9%和26.4-99.0%。在S1-D_1条件下，河农825叶片Pn降低的主要原因是光强降低。随着遮荫强度和遮荫时间的增加，叶片Pn下降的原因是光照强度低，气孔导度和叶绿素含量低，叶绿体和光合作用系统的超微结构受损。在S2-D7胁迫下，合农825的叶绿素含量、Fv/Fm(光系统II的最大光化学效率)和Jmax(最大电子传递)分别降低19.6%、5.2%和28.8%，科农9204分别降低29.9%、7.8%和33.1%。去遮荫处理后，克农9204在D5和D7处理的叶片Pn均达不到对照水平。结果表明，遮荫时间较短(小于3天)时，叶片Pn降低的主要原因是遮荫时间较短(小于3天)时，叶片Pn降低的主要原因是遮荫时间较长(大于5天)时，叶片Pn降低主要是由于遮荫时间较长(大于5天)时，叶片Pn降低的主要原因是由于遮荫时间较短，叶片光合作用系统受到破坏，特别是对遮荫敏感的品种科农9204。
The young microspore (YM) stage is the most sensitive period for wheat grain formation to abiotic stress. Shading stress during YM stage reduces grain yield mainly due to grain number decrease. However, the photosynthetic base for grain number decrease is still unclear. In this study, 100% (control), 40% (S1), and 10% (S2) of natural light were applied for 1, 3, 5, and 7 days (D1, D3, D5 and D7) during YM stage of two wheat cultivars (Henong825, Kenong9204). The results showed that grain number in Henong825 and Kenong9204 was reduced by − 3.6 to 33.3% and 14.2–72.7%, respectively. The leaf photosynthetic rate (Pn) in Henong825 and Kenong9204 was deducted by 4.5–93.9% and 26.4–99.0%. Under S1–D1, the leaf Pn of Henong825 reducing was mainly due to the reduction of light intensity. With shading intensity and duration increasing, the reasons for leaf Pn decrease were the low light intensity, the low Gs (stomatal conductance) and chlorophyll content, the damage of ultrastructure of chloroplast and photosynthetic system. Under S2–D7, the chlorophyll content, Fv/Fm (maximal photochemical efficiency of photosystem II) and Jmax (maximum electron transport) were reduced by 19.6%, 5.2% and 28.8% in Henong825, and by 29.9%, 7.8% and 33.1% in Kenong9204. After shading removal, the leaf Pn of Kenong9204 under D5 and D7 could not reach to the level of CK. This study indicated that the reduction of leaf Pn was mainly due to the low light intensity under short shading duration (shorter than 3 days), and due to low light intensity and damage of the leaf photosynthetic system under longer shading duration (longer than 5 days), especially for Kenong9204 (shade-sensitive cultivar).