孕穗期冬小麦及田间优势杂草光合特性对模拟光强的响应

2006年4-5月冬小麦孕穗期利用Li-6400便携式光合测定系统测定了模拟光强(simulated photosynthetic radiation,SPR)下麦田杂草小花糖芥(Erysimum cheiranthoides)、酸模叶蓼(Polygonum lapathifolium)、小蓟(Cephalanoplos lapathifolium) 和冬小麦(Triticum aestivum)的净光合速率(P_n)、蒸腾速率(T_r)、气孔导度(G_s)、胞间CO_2浓度(C_i)、叶面温度(T_l)及叶面饱和蒸气压亏缺(V_(pdl)).结果表明:3种杂草和冬小麦随光强增加P_n增大,小蓟和酸模叶蓼分别在SPR为700和1300 μmol·m~(-2)·s~(-1)出现光饱和,小花糖芥和冬小麦在模拟光强范围内没有出现光饱和.T_r、Gs随SPR增加响应趋势一致,冬小麦、小花糖芥呈上升趋势,小蓟下降,酸模叶蓼气孔导度对SPR反应不敏感,保持在0.3 mol·m~(-2)·s~(-1)左右,T_r保持在大约5.0 mmol H_2O·m~(-2)·s~(-1),显著高于冬小麦和其它杂草(p<0.05).冬小麦和小花糖芥T_1 和V_(pdl)随SPR增加变化较小,且高于小蓟和酸模叶蓼.模拟光强条件下小花糖芥与冬小麦的光合特性相似,是麦田自然资源的主要竞争者.

Responses of Photosynthetic Characteristics of Wheat at Booting Stage and Weeds Species to Simulated Photosynthetic Radiation

The portable photosynthesis system Li-6400 was used to compare net photosynthetic rate (P_n), transpiration rate (T_r), stomatal conductance (G_s), intercellular CO_2 concentration (C_1), leaf temperature (T_1), and vapor pressure deficit ( V_(dpl) ) of wheat ( Triticum aestivum ) and weeds Erysimum cheiranthoides, Cephalanoplos segetum , and Polygonum lapathifolium under varying simulated photosynthetic radiation in a wheat field. The results showed that Pn of wheat and three weeds increased as SPR was tuned up. P_n of C. segetum and P. lapathi folium reached light saturation when SPR was 700 and 1300μmol·m~(-2)·s~(-1), but E. cheiranthoides and wheat were not in the range of SPR. T_r, and G_s of E. cheiranthoides and wheat increased with SPR, while C. segetum decreased. G_s of P. lapathi folium was not susceptive with SPR changes, which was at about 0. 3 mol H_2O·m~(-2)·s~(-1) , and T_r was at about 5.0 mmol H_2O·m~(-2)·s~(-1) , which were all significantly higher than wheat and other weed (P<0.05). T_1 and V_(pdl) of wheat and E. cheiranthoides did not change with the increase of SPR, and were higher than P. lapathifolium and C. lapathifolium. Photosynthetic characteristics of E. cheiranthoides for the response of light intensity were similar to wheat, and this weed was a formidable competitor for natural resource in wheat field.