湘西南湿热地区不同秋眠级紫花苜蓿光合特性研究

Study on the Photosynthetic Characteristics of Alfalfa with Different Fall-dormancy Levels in the Southwest Region of Hunan Province

利用Li-6400光合速率测定系统测定了16种不同秋眠级紫花苜蓿(Medicago sativa L.)品种的净光合速率、气孔导度、蒸腾速率、胞间CO2浓度、光量子通量密度、水分利用率;同时对不同秋眠级紫花苜蓿草产量进行测定。结果表明:阿尔冈金(Algonquin)、四季旺(Overseason)、维多利亚(Victoria)、WL525、萨兰多(Salado)、WL414、CW403、721丰叶(721Amerilea)、皇后2000(Empress2000)、牧歌,701(Amerigraze701)、丰宝(Powerplant)的光合速率日变化曲线呈双峰型,而CW400、CW680、路宝(Lobo)、猎人河(Hunter River)、盛世(Millenium)呈三峰型,16个品种净光合速率日变化均出现午休现象,其变化规律与秋眠级没有相关性;盛世、牧歌701、丰宝净光合速率较高在20μmolCO2.m-2.s-1以上;牧歌701、路宝、WL525蒸腾速率较高在均在10 mmolH2O.m-2.s-1以上;CW403、721丰叶(721Amerilea)水分利用率较高,达5μmol CO2.mmol H2O-1以上。在湘西南湿热地区环境气候条件下,盛世、牧歌701、丰宝、4季旺等光合能力较强、蒸腾速率高的品种可作推广种植。

The diurnal variations of net photosynthesis rate（Pn）,stomatal conductance（GS）,transpiration rate（Tr）,intercellular CO2 concentration（Ci）,photon flux density（PFD）,and water utilization efficiency（WUE） of 16 alfalfa cultivars with different fall-dormancy levels were measured using Li-6400 Portable Photosynthesis System and the yields were measured at same time.The results show that cultivars Algonquin,Overseason,Victoria,WL525,Salado,WL414,CW403,721Amerilea,Empress2000,Amerigraze701,and Powerplant had the diurnal variation laws with the bimodale shape in the Pn;and CW400,CW680,Lobo,Hunter River,and Millenium the ternary-peak shape in the Pn.An obvious ＂midday-rest＂ phenomenon in Pn was shown for each alfalfa cultivar and no correlation was detected between it and full-dormancy level.Cultivars Millenium,Amerigaze701,and Powerplant had higher Pn which was above 20 μmolCO2·m^-2·s^-1;Amerigaze701,Lobo,and WL525 had higher Tr which was above 10 mmolH2O·m-2·s-1;CW403 and 721Amerilea had higher WUE which was above 5 μmolCO2·mmolH2O-1.In the circumstance of southwest region of Hunan province,cultivars with higher Pn and Tr should be planted widely.