The Change of Photosynthetic Activity and the Varietal Difference in the Ripening of Tobacco

[摘要] An investigation was made on the relation between photosynthetic activity and the amount of internal constituents, especially of nitrogen components, and furthermore, on the difference of their relation between varieties. Using two flue-cured tobacco vareities, Hicks and Bright Yellow, photosynthesis and respiration were measured on the detached 6th, 9th and 11th leaves from the bottom, after the time of topping to that of harvest The results obtained were summarized as follows: 1. Photosynthesis and protein nitrogen content on leaf area basis decreased gradually with the progress of leaf age. But the decrease was rather steeper in protein nitrogen, total nitrogen and potassium concentration on dry matter basis. 2. Correlation between photosynthesis and above mentioned nitrogen constituents had most intimate relation with photosynthesis. This result revealed that protein nitrogen content had most intimate relation with photosynthesis. Potassium concentration was also seemed to be related with photosynthesis to some extent. 3. Partial correlation between protein nitrogen content, potassium concentration and photosynthesis were calculated to study independent relation values between each constituents and photosynthesis. The partial correlation coefficient between photosynthesis and potassium, independent of protein nitrogen content, was lower than that of simple correlation coefficient between potassium and nitrogen protein content. From this fact, it was assumed that potassium would not affect on photosynthesis directly, but indirectly through the metabolism of protein. 4. Difference of each components in two varieties was compared in the course of growing stages of tobacco. Photosynthesis, respiration and nitrogen contents were higher in Hicks than in Bright Yellow, but Photosynthesis per protein nitrogen content was lower in Hicks. The difference of photosynthetic activity was considered to originate from the difference of protein level.

[学科分类] 农业科学（综合）