Stable cultivation techniques of row sown direct seeding into puddled and leveled soil of paddy fields in the Shonai area [Japan]

"The objective of this research is the establishment of the cultivation techniques of direct row sown rice variety ""Haenuki"" in flooded paddy field in Shohnai area of Yamagata prefecture, and the cultivation techniques enable to get planting-cultivation-level yield (580kg/10a)and quality. So, We attempted to explain about the problems and their solutions for the achievement of the objective, and about the proper growth index and the cultivation techniques to realize it. The outline of the growth index to achieve the objective is following. 1 Proper panicle number is about 30,000/square m, and which is grotten with about 500/square m ear number. 2 Tiller number 600-750/square m at 9th leaf period (nearly after time of the last bearing tiller emergence) is necessary to get this ear number. 3 Seedling number 60-100/square m is necessary to get this stem number. 4 Heading date ealier than August 15th is necessary for the satisfactory ripening condition. In Shonai area, there is two problems to be solved for the realization of this index. 1 The insufficiency of panicle number caused by the withering at middle growing stage in the paddy field of medium and coarse strong gley soil with poor soil fertility. 2 The insufficiency of panicle number caused by the poor seedling number and the inferior growth level at the early growing stage in the paddy fields of fine textured strong gley soil. The techniques to solve these problems and the techniques to lead to the index are following. 1 The early heading date (earlier than August 15th) ensured by the early seeding date in last 5days of April (about ten days earlier than usual). 2 Minimum budding number is ensured with ponding water release after seeding, inspite of low temperature condition in this seeding date. 3 The decision of use or unuse of topdressing on 3rd leaf period and 5th leef pireod, according to seedling number. 4 The decision of topdressing technique after 9th leaf period, with the diagnostic technique at 9th leaf period. By the overall use of these techniques, we have succeeded in the achievement of our intend-ed objective."