On the boron deficiency in plant. II.The external boron deficiency symptoms and boron requirements of “Kenaf”plants in culture solutions

The results obtained in this studies are summarized as follows : 1) The presence of boron in dilute concentration is essential to continue the growth of “Kenaf\u22 plants in chemically pure water culture solution. 2) For the life cycles of Kenaf plants, boron above 0.025p.p.m. must be contained in the nutrient culture solutions renewing them once a week. 3) Supplying the boron to boron-starved plants soon after the boron deficiency symptoms appeared, they enable to reestablish their ordinary growth in their life cycles. 4) Kenaf plants grown in nutrient solution free from boron develop the following symptoms of boron deficiency : (a) poor development, roughness and discoloration of root system, (b) chlorosis, thickening and wrinkling of the leaves, (C) appearance of small and short fissure(or split)like lines and scabs on the surface of petioles and stems,(d) petioles, sometimes also stems, bend, (e)characteristic brittleness of the stems and leaves,(f) cessation of the terminal growth of the stem. 5) Bending phenomena of petiole is most clear, definite and easy visible symptom of boron deficiency.繊維作物の一種である“ケナフ”(Hibiscus cannabinus) が示す硼素缺乏症状に就いて報告する．著者の知る限りでは,従来あげられている硼素の指示植物の孰れよりも“ケナフ”は秀れているものであると推称したい程に，著しい且つ発見しやすい缺乏症状の数々を呈供する植物である．以下その概略を記述することにする