超高产冬小麦冬前光合性能研究初报

为明确冬小麦冬前光合性能的动态变化及其影响因素,为通过栽培措施调控培育冬前壮苗提供研究依据,用光合测定仪在田间条件下对每公顷产量9t左右的超高产冬小麦冬前叶片的光合性能进行了初步研究。结果表明:4个冬小麦品种不同叶位叶片的净光合速率(Pn)、蒸腾速率(TR)和气孔导度(gs)的变化趋势相似,都是在测定始期或稍后出现最高值,之后逐渐下降,并受到冬前初次剧烈降温的影响而骤降至低谷,之后又有所回升。不同叶位个光合参数的回升幅度有所不同,高位叶的Pn较低位叶回升明显,而低位叶的TR和gs较高位叶回升明显。Pn,TR和gs与有关生态条件的相对变化方向及相关分析表明,冬前叶片Pn和gs受气温和光合有效辐射(PAR)的双重影响,而TR主要受气温的影响。不同叶位之间,叶片光合性能的综合能表现为第3叶>第1叶>第2叶>第4叶,它们之间的差异主要由叶面积不同产生。

A Preliminary Study on the Photosynthetic Performance of Super High Yielding Winter Wheat during Pre-winter Period

In order to make clear the dynamics of photosynthetic performance of winter wheat during pre-winter period and the factors affecting photosynthesis, a determination was conducted using a photosynthesis measuring system in the fields of winter wheat with grain yield about 9t/hm2 for four varieties. The main results showed that, the dynamics of net photosynthetic rate (Pn), transpiration rate (TR) and stomatal conductivity (gs) of the leaf blades at different positions on the main stem for all varieties were similar. All the photosynthetic parameters above reached the maximum values at the beginning of determination or a little later, then decreased gradually. A sharp decrease leading to the lowest value of the parameters occurred owing to the first dramatic decrease of temperature. Recovery of the parameters occurred thereafter, but the Pn of leaves at higher position recovered more prominent than those of lower leaves, while the TR and gs of lower leaves recovered better. The dynamic tendency of Pn, TR, gs and the relevant ecological factors and correlation analysis showed that, Pn and gs of leaves during pre-winter period were affected by both temperature and PAR, but TR was cotrolled by temperature only. The synthetic performance of photosynthesis of the 3rd leaf was the best, then the 1st, 2nd and 4th in order, and the difference among these leaves mainly came from the difference of their leaf area.