Abstract
We have carried out stress diagnosis of lowland rice by measuring stress-related compounds to examine the stresses by which rice plants suffer from severe injury during their growth period and to clarify the environmental factor causing withering of leaf margin that has been observed at the north mountainous region in Nagasaki prefecture. Abnormal leaves appeared at the middle of August. The levels of polyamine and ACC apparently increased in the abnormal leaves, indicating the response of these compounds to severe stress. Leaf ACC level in rice increased during and over the rainy season when acid mist had been hovering over this area. As for leaf polyamine, striking increase was observed at the middle of August. These results suggest that weak stress occurred during and over the rainy season but the serious environmental stress, which could induce severe leaf injury, occurred from the beginning to the middle of August.
