Boron deficiency of sunflower (Helianthus annuus.)

해바라기의 붕소결핍(硼素缺乏)

Boron deficiency appeared as a cause of poor growth of sunflower(Helianthus annuus) according to soil and plant analysis. The investigated results are as follows; 1. Boron deficiency was due to low content of available boron (hot water soluble) in soil and clitical concentration appeared as 0.17 ppm. 2. Clitical concentrations in plant appeared to be 20 ppm for head(flower), 25 for leaf, 15 for stem and 10 for root. Boron concentration among positional leaves was greatly decreasing in the upper leaves. 3. Soils low in boron were relatively higher in calcium, silica and pH than in normal soil but relationship between boron and organic matter or other nutrients was uncertain. 4. The content of Ca and P is high in the head of boron deficient plant but low in root. Plants deficient in boron also showed a tendency of high N and low K but no clear tendency was shown in Mg and Fe. 5. Symptoms of boron deficinicy were yellowing of upper leaves, browning and drying of upper part of stem, cracking and blackening of stem and roots resulting short stem and poor growth.

해바라기의 생육불량(生育不良) 원인(原因)을 토양(土壤) 및 식물체(植物體) 분석(分析)에 의(依)하여 본 결과 붕소결핍(硼素缺乏)으로 나타났으며 다음과 같은 결과를 얻었다. 1. 붕소결핍(硼素缺乏)은 토양(土壤)의 유효붕소함량(有効硼素含量)(열수침출(熱水浸出))이 적은데 기인(基因)했으며 유효붕소(有効硼素) 임계농도(臨界濃度)는 0.17ppm으로 나타났다. 2. 식물체(植物體)에서의 임계농도(臨界濃度)는 화부(花部)(두부(頭部))에서 15ppm 근(根)에서는 10ppm으로 나타났다. 상위엽(上位葉)으로 갈수록 B함량(含量)은 상당히 감소하였다. 3. 붕소(硼素)가 적은 토양(土壤)은 Ca가 많았으며 유기물(有機物)이나 산도(酸度) 기타 양분(養分)과의 관계가 불확실했다. 4. 붕소결핍(硼素缺乏)된 식물체(植物體)는 Ca와 P가 두부(頭部)에는 높고 근부(根部)에 낮으며 N는 높고 K는 낮은 편이며 Mg와 Fe는 관계가 불확실했다. 5. 붕소결핍(硼素缺乏)은 줄기와 상부(上部)의 갈변고사(褐變枯死) 및 줄기와 뿌리가 부분적으로 파열(破裂)되고 흑변(黑變)하였다.