Salt water selection - Ensuisen

This is one of the gravity selection methods to select good seeds. The degree of fullness of the inside of the seeds compared to the outer shell is determined by soaking them in a solution of salt or ammonium sulfate with a fixed specific gravity, and the selection is made by seeing whether they float or sink. This is different from selection based on the true specific gravity of the seeds. It is particularly widely used when selecting rice seeds. The heavier and more mature the rice, the larger the embryo and the more nutritious the endosperm. Such rice has strong germination vigor and excellent early growth, making it ideal for use as seeds. The specific gravity of the solution used in salt water selection varies depending on the type of crop. For non-glutinous rice, salt water with a specific gravity of 1.13 (about 250 grams of salt in 1 liter of water) is used, and for glutinous rice, non-glutinous rice with awns, upland rice, etc., salt water with a specific gravity of 1.08 to 1.10 (about 170 to 180 grams of salt in 1 liter of water) is used. The seeds are soaked in salt water with a volume about twice the amount of the seeds, stirred, and the floating seeds are discarded and the sinking seeds are used. After salt water selection, the seeds are thoroughly washed with water. In addition to rice, salt water selection is also carried out on wheat, barley and other crops.

[Hoshikawa Kiyochika]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

よい種子を選ぶための比重選の一つ。種子の外殻に対する中身の充実の程度を、食塩や硫酸アンモニウムの一定比重溶液につけてその浮沈によって選別するもので、種子の真の比重による選別とは異なる。とくにイネの種もみを選ぶ場合に広く行われている。よく実った重いもみほど胚(はい)が大きく、胚乳養分量も多い。このようなもみは発芽の勢いが強く、初期の生育が優れているため、種もみとするのに好ましい。塩水選に用いる溶液の比重は、作物の種類によって異なる。うるち稲には比重1.13（水1リットルに食塩約250グラム）、もち稲や芒(のぎ)のあるうるち稲、陸稲などには比重1.08～1.10（水1リットルに食塩約170～180グラム）の塩水を用いる。種子の約2倍量の塩水に浸し、かき混ぜて、浮いた種子は捨て、沈んだ種子を用いる。塩水選後は種子をよく水洗いする。イネのほかコムギ、オオムギその他の作物でも塩水選が行われる。

［星川清親］

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