Jia Yuanli, Wang Tao, Zhou Gaozi, Tang Lei, Yue Xueping, Liu Xinrui, Cao Tao, Yang Juan, Tao Youfeng, Deng Fei, Zhou Wei, Ren Wanjun, Chen Yong
Crop Ecophysiology and Cultivation Key Laboratory of Sichuan Province, Key Laboratory of Crop Ecophysiology and Farming System in Southwest China, Ministry of Agriculture, Sichuan Agricultural University, Chengdu, China.
Front Plant Sci. 2023 Oct 4;14:1213609. doi: 10.3389/fpls.2023.1213609. eCollection 2023.
The mesocotyl facilities the emergence of deep-sown rice. However, the effects of mesocotyl elongation on mechanically transplanted rice seedlings remain unclear. In this study, the indica three-line hybrid rice Chuanyou 6709 (CY6709) and the indica conventional rice Guichao II (GCII) were selected as experimental materials. The seedlings were grouped based on mesocotyl lengths of 1.0 and 2.0 cm (M1 and M2, respectively), and seedlings without mesocotyl elongation were used as a control (M0). Seedling morphology, root morphology and physiology, and dynamic changes in soluble sugar and protein, malondialdehyde (MDA), and antioxidant enzyme activity in the mesocotyl were evaluated. The results showed that the elongation of mesocotyl is not conducive to improving the quality of mechanically transplanted seedlings, resulting in weak seedlings and poor root coiling force. The mesocotyl lengths of the seedlings showed a single peak with increasing seedling age, which gradually disappeared. The longer the mesocotyls, the slower their senescence. The MDA content of M2 was significantly lower than that of M1, and the activities of soluble sugar, soluble protein, and antioxidant enzymes of M2 were higher than those of M1, implying that seedlings with longer mesocotyls yielded lower-quality seedlings, reducing their suitability for mechanized transplantation. Compared with those of M0, the root-shoot ratio, stem base width, leaf age, leaf area, white root number, root coiling force, root length, root surface area, and root volume of M1 and M2 were reduced. Therefore, in the raising of rice seedlings, excessive elongation of the rice mesocotyl is not conducive to optimum root growth and development of aboveground structures for seedlings that are suitable for mechanized transplantation. Controlling the mesocotyl elongation can facilitate the cultivation of high-quality mechanically transplanted seedlings.
中胚轴有利于深播水稻的出苗。然而，中胚轴伸长对机械插秧稻秧苗的影响尚不清楚。本研究选用籼型三系杂交稻川优6709（CY6709）和籼型常规稻桂朝二号（GCII）作为试验材料。根据中胚轴长度1.0厘米和2.0厘米将秧苗分组（分别为M1和M2），将没有中胚轴伸长的秧苗作为对照（M0）。对秧苗形态、根系形态与生理以及中胚轴中可溶性糖、蛋白质、丙二醛（MDA）和抗氧化酶活性的动态变化进行了评价。结果表明，中胚轴伸长不利于提高机械插秧秧苗质量，导致秧苗瘦弱、根系盘绕力差。秧苗的中胚轴长度随秧龄增加呈单峰变化，该变化逐渐消失。中胚轴越长，其衰老速度越慢。M2的MDA含量显著低于M1，M2的可溶性糖、可溶性蛋白质和抗氧化酶活性高于M1，这意味着中胚轴较长的秧苗培育出的秧苗质量较低，降低了其对机械化移栽的适应性。与M0相比，M1和M2的根冠比、茎基部宽度、叶龄、叶面积、白根数、根系盘绕力、根长、根表面积和根体积均降低。因此，在水稻育秧过程中，水稻中胚轴过度伸长不利于培育出适合机械化移栽的秧苗的地上结构的最佳根系生长发育。控制中胚轴伸长有助于培育高质量的机械插秧秧苗。
