富士市における秋播早生カンラン生産の推移と所謂心腐れ症の発生について : 蔬菜産地における土壌の生産力低下の1例として(第3報)

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In the previous papers, we described the results of experiments concerning the inferior growth of onion planted following cabbage, a phenomenon pe-culiar in Fuji district known for its production of early spring cabbage. Now, in recent years, the production of early spring cabbage itself decreased rapidly; for exam-ple, annual acreage, production and yield value in 1959 were 110 ha, 1700 tons and ¥17, 787, 000 res-pectively as compared with 250 ha, 5600 tons and ¥86, 196, 000 in 1955. This acute drop of cabbage production is remark-able especially in the central area of this district where cabbage has been grown successively year after year, while in the surrounding area where cabbage is a new crop or has been grown in rota-tion with barley, the normal growth and early har-vesting are possible as it was once so in the central area. One of the causes of this decline is the occurrence of nutritional disorder which appeared as the so called “heart rot” for the first time in the spring of 1957 and successively in 1958, and another is the severe infection of Botrytis. The nutritional disorder seems to be due to the calcium deficiency or rather the failure of calcium absorption and its characteristics, which are strik-ingly similar to some of the calcium deficiency symptoms observed in sand and water cultures, are as follows: when appear before heading; the darkening of leaf color and the splitting and brown-ing of the margins of green leaves: when appear after heading; the hooking and the development of water-soaked areas around the margins of head leaves which turn light brown, in both cases second-ary invasions of soft rot bacteria can be often recognized. The severe occurrence of this disorder has been seen, as above-mentioned, especially in the central area where cabbage had been grown successively and consequently supplied with a great deal of in-organic fertilizers, and moreover it has been seen exclusively following dry winter as in 1957 and 1958, while no occurrence following wet winter as in 1959. In addition it is noteworthy that even in the central area the disorder has been mild in the fields with high water table and also that even in the year in which no disorder occurred in the fields, typical calcium deficiency symptoms appeared in all of the cabbage plants grown under glass cover for seed growing, perhaps due to drying of the soil under glass. Now, we investigated the relation of the occur-rence of calcium deficiency in cabbage to the com-position of culture solution, as its occurrence in celery and tomato had been elucidated to be due to the high salt concentration or the unbalance of the nutrients. The results were as follows. Among seven treatments (culture solutions) includ-ing the standard (Ca 7m. e./l), -Ca (Cal m. e./l), (-Ca)×3, -Ca+NH4, -Ca+K, -Ca+Mg and-Ca+Na (in the latter four treatments, 6(=7-1) m. e./l of Ca was substituted by each of NH4, K, Mg and Na), the growth was superior in the standard, -Ca+K and -Ca+Na while inferior in(-Ca)×3 and -Ca+Mg. Visual deficiency symptoms on the green leaves before heading appeared only in (-Ca)×3, while those on the head leaves, which were often com-plicated with and difficult to distinguish from the decay due to bacteria, developed severely in all of the treatments except the standard and there was little difference in its severity. In addition, it was very interesting that the sudden infection of soft rot bacteria occurred on the outer head leaves immediately before harvest, and it was most severe in -Ca+Mg, followed by -Ca+K, while almost no infection occurred in the standard. Prior to this infection the marginal wilting of the outer head leaves was seen in some plants but the relation of this wilting to the bacterial infection was not clear

富士市における秋播早生カンラン生産の推移と所謂心腐れ症の発生について : 蔬菜産地における土壌の生産力低下の1例として(第3報)

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