Formula for Determining Number of Basic Seedlings at Scattered-Planting with Seedling Dry-Raised on Plastic Trays in Double-Season Rice

摘要

The tiller emergence in seedling nursery beds and field, and panicle formation in the field were investigated under scattered-planting with seedling dry-raised on plastic trays in double-season rice. A significant difference was noted in the non-synchronously-emerged tillers (the tillers that formed from latent buds and did not emerge following the normal tillering law on seedling nursery beds and recovered to grow after scattered-planting or transplanting) as well as the percentage of the available synchronously-emerged tillers between seedlings raised on plastic trays under dry-land conditions (DPT) and seedlings raised on nursery beds under wetland conditions (WB). The seedlings under DPT had some non-synchronously-emerged tillers, but those under WB had not. Therefore, the traditional formula for determining the number of rice seedlings was improved, and the formula for determining the number of basic seedlings under scattered planting with DPT in double-season rice was introduced. For early rice, it was X=Y/{(1+t1r1)1+(N-n-SN)Rr2+(SN-3-t1)R2r5}, and for late rice, it was X=Y/{(1+t1r1)1+(N-n-SN)Rr2+(N-n-SN- 3)Rr2R1r3+(SN-3-t1)R2r5}. Where, X represents reasonable number of basic seedlings per unit area at scattered-planting; Y, number of fitting paniclesper unit area; t1, total number of tillers per plant; r1, percentage of the total available tillers; N, total number of leaves of the main culm; n, total number of elongated internodes in the main culm; SN, seedling leaf ages at scattered-planting; R, percentage of the primary tillers emerged in available node-position; r2, percentage of the available primary tillers; R1, percentage of the secondary tillers in the field (except the secondary tillers of the seedlings); r3, percentage of the available secondary tillers; R2, percentage of the asynchronously-emerged tillers after scattered-planting; r5, percentage of the available non-synchronously- emerged tillers after scattered-planting.