The effects of recycled paper-mulch, which weighted three fourths of the conventional paper-mulch, on the weed control in rice transplanting cultivation were examined at the plain regin and hilly and mountainous region of Tottori Prefecture. In the plain region covering with the light-weight and black-colored recycled paper-mulch was more effective than when using the light-weight or conventional undyed recycled paper-mulch for weed control. In the hilly and mountainous region at an altitude between 210 and 310 meter above the sea level, the light-weight and black-colored recycled paper-mulch was also as effective as the conventional black-colored recycle paper-mulch. In both regions light-weight and black-colored recycled paper-mulch showed good performance of practical use. About 99.5% of barnyard millet, one of the harmful weeds in the paddy, were controlled by using the recycled paper-mulch. We developed a method of assessing when to introduce or contine use of recycled paper-mulch for rice cultivation based on the population density of barnyard millet.

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To elucidate the relationships between the internode elongation on the main stem and branches, we examined relationships between the leaf emergence and internode elongation at each node position in determinate cv. Enrei and indeterminate cv. Touzan 69. The rate of leaf emergence per day was higher in Enrei (0.44 leaf/day) than in Touzan 69 (0.35 leaf/day). The time of leaf emergence from the nth node (counted from the cotyledonary node) on the main stem coincided with that from the branch developed from the (n-4)th node. The final length of the internode on the main stem was shortest at the 2nd or 3rd internode (internode between cotyledon and primary leaves is called 1st internode), and longest at the internode just below the node from which no branches developed. The higher the internode position beyond this node, the shorter the length of internode. In both cultivars, the nth internode began to elongate when the elongation of (n-3)th or (n-4)th internode was completed. The leaf emergence from the nth node coincided with the elongation of the (n-4)th internode. In Enrei, the nth internode of the main stem began to elongate coincidently with the first internode of the branch appearing from the (n-3)th node on the main stem. A close relation was observed in the patterns of the leaf emergence and internode elongation between the main stem and branches of soybean plants.

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