冬季低温条件下麦类作物光合性能的初步研究

A Preliminary Study on Photosynthetic Performances of Wheat,Barley,Oats and Rye at Low Temperature in Winter

本文以田间种植的4种麦类作物幼苗为材料，从进入越冬期的小雪（11月23日）开始，在田间条件下相当于日最高气温的时段内，测定了叶片的净光合速率（Pn）、蒸腾速率（TR）和水分利用效率（WUE）。结果表明：（1）4种麦类作物叶片的Pn和TR，均随测定期间气温（Tair）的不断下降而逐渐降低，而与测定期间光照强度（PAR）和空气相对湿度（RH）的起伏变化关系不密切。（2）TR的下降比Pn下降更为明显，尤其在气温降到零下时TR降低更甚。（3）即使气温降到－2℃时，麦类作物的Pn和TR仍为正值。（4）光合作用中的WUE随气温降低而逐渐提高，在气温降到零下时提高更为显著。（5）测定期间的平均Pn以黑麦为最高，小麦和大麦其次，燕麦最低；TR以小麦最高，以下依次为燕麦、黑麦和大麦，但气温降到零下时以燕麦最低；WUE以黑麦最高，大麦稍次，最低为小麦。如以Pn和TR受低温影响降低较少作为抗寒性表现，则4种麦类作物的抗寒性以黑麦最强，其次为小麦和大麦，燕麦最弱且光合生产力最低。

in this paper, the net photosynthetic rate (Pn), transpiration rate (TR), andwater use efficiency (WUE) of leaves of field-grown wheat, barley, oats and rye were determinated at field conditions from Nov. 23, 1989 to Jan. 6, 1990. The results showed that:(1) Leaf Pn and TR of all the four crops decreased with the decreasing air temperature, butrarely changed with the fluctuation of light intensity and relative humidity. (2) TR decreased more evidently than Pn did, especially at low temperature below 0'C. (3) When airtemperature was as low as -2℃,Pn and TR were still positive values. (4) WUE increasedwith the decreasing temperature, and was significantly high below 0℃. (5) The average Pnof all measurements of rye was the highest , and those of wheat and barley secondly ,and the lowest for oats , in the four crops ; The highest TR was given by wheat , and lowered in the ooder of oats , rye and barley , but TR of oats became the lowest when temperature was be-low 0℃; The maximum WUE was showed in rye , and that of barley a little lower , with that of wheat the lowest . If the decreases of Pn and TR affected by low temperature were taken as the expression of cold tolerance , or resistance , then the order of cold resistance of the fourcrops should be rye , wheat and barley in the same level , and oats comes last.