拔节期光强对水稻基部节间长度的影响

基部节间过长是导致水稻倒伏的关键因素之一。光强对水稻茎秆基部节间长度有重要影响。本研究在拔节前1叶龄期(S_0)、第1节间伸长期(S_1)以及第2节间伸长期(S_2),采用遮阳网遮光的方法,设置3种不同光强:29%透光率(A)、67%透光率(B)和100%全光照(不遮光,C),研究不同节间伸长期光强对节间长度的影响。结果表明,在拔节前1叶龄期,基部第1、第2和第3节间长度在不同光强处理间均无显著差异;在第1节间伸长期和第2节间伸长期,随着光强的增加,正在伸长的节间显著缩短,但光强对其他伸长节间的长度无显著影响。回归分析表明,光强与正在伸长的基部节间长度呈显著负相关关系,而与其他伸长节间长度的相关性不显著。在第1节间伸长期,光强每增加1 000 Lum/ft~2,第1节间将缩短0.5 cm;而在第2节间伸长期,光强每增加1 000 Lum/ft~2,第2节间则缩短0.7 cm。上述结果表明,光强仅对正在伸长节间的长度产生显著影响,其中第2节间对光强的反应比第1节间更为敏感。在生产实践中可通过栽培调控提高群体透光率,避免基部节间过度伸长,从而提高水稻抗倒伏能力。

Effects of Light Intensity During Jointing Stage on Basal Internode Length of Rice

Internode length is one of the main traits affecting the lodging resistance of rice.Light intensity can exert a profound influence on the internode length of rice.But so far,the mechanism underling the role of light intensity on the internode elongation is not well understood.A field experiment was conducted to explore the effects of light intensity on basal internode length by artificial shading.During the stages of the 1-leaf age before jointing (So),the 1st internode elongation stage (S1) and the 2nd internode elongation stage (S2),rice plants were subjected to three different light regimes:29％ of full sunlight (A),67％ of full sunlight (B) and full sunlight (no shading,C).In treatment A,plants were shaded with black shading nets.In treatment B,plants were shaded with white shading nets.The light intensity in the basal parts of the rice stem and the length of the 1st,2nd and 3rd internode were measured.The results were as follows:1) In So stage,the light intensity has no significant influence on the length of the 1st,2ud and 3rd internodes.In S1 and S2 stages,the length of the elongating internodes was significantly decreased with the increasing of light intensity,while no significant impact of light intensity was found on the length of non-elongating internodes.2) Regression analysis indicated that the light intensity was significantly and negatively correlated with the length of the elongating internode,but was not significantly correlated with the length of non-elongating internodes.For every 1 000 Lum/ft2 increase in light intensity during S1 stage,the 1st internode length was reduced by 0.5 cm,while during S2 stage,the 2nd internode length was reduced by 0.7 cm.The 2nd internode was more sensitive to the variation of light intensity compared with the 1st internode.In practice,increasing the light transmission into the basal parts of the rice canopy would be an efficient way to shorten basal internodes and improve lodging resistance.