柑橘缺硼症之診斷與防治方法之研究

A Study on Diagnosis and Correction of Boron Deficiency in the Citrus Orchard

邱再發(C. F. Chiu) ； 張淑賢(S. S. Chang)

《中華農業研究》 32卷2期 (1983/06) Pp. 161-171

https://doi.org/10.29951/JARC.198306.0008

摘要

民國65年10月底獲知東勢鎮有一椪柑及柑桶園發生病態果實，果型變小、堅硬如石、剝開則絨層變硬加厚，瓣囊縮小退化而無汁，但果樹之枝葉生長仍然正常。此症狀疑似缺硼症，經採取該園之果實及其上方之春梢葉片之樣品進行分析，結果顯示葉片與果皮中硼含量均在10ppm以下，遠低於Chapman等氏所提之正常濃度範圍(25-150ppm)，故推斷此一異常係缺硼所致。爲進一步證實之，並探討安全之硼素施用量與施用方法及覆草對硼素吸收之影響，並觀察施硼之殘效，乃自66年至70年間進行試驗，處理分爲(1)對照，不施硼(2)土壤施用硼酸40g/株(3)土壤施用硼酸120g/株(4)0.3%硼酸液每年葉面噴施兩次(5)土壤施用硼酸40g/株＋0.3%硼酸液葉面噴施(6)土壤施用硼酸40g/株＋覆草20公分等。試驗結果摘述如下：
1．試驗果園之土壤熱水可溶性硼含量低，表土(0-15cm)含0.15ppm，底土(15-30cm)含0.10ppm。當乾旱之年缺硼症即發生，此時葉片及果皮中之硼濃度均在10ppm左右。但雨量充足之年則無缺硼症發生，此時八月之春梢非結果枝葉片含硼20ppm左右，果皮含14ppm。若於果實肥大期缺硼，則異常之石頭柑發生；若於春梢萌發至開花結果期缺硼，則結果量低。
2．春梢非結果枝葉片中之硼含量隨葉齡增加而增加，即老葉硼濃度高於新葉。但缺硼之柑樹，無論新葉或老葉硼含量均低。
3．在10年生、中細質地土壤之缺硼柑園，於樹冠下之土壤表面撒施40-120g/株硼酸，可安全矯正缺硼症，且其殘效可維持四年以上。硼酸施用之當年，葉片磷濃度隨硼酸施用量之增加而降低，兩者之負相關顯著。故於類似本試驗園條件之缺硼柑園，宜施50g/株之硼酸以防治缺硼，且一次施用，四年內不宜再施。惟此用量應視樹齡及土壤質地而調整。
4．每年於葉面噴施兩次0.3%硼酸液（亦可矯正缺硼症），但葉片中硼濃度逐年增加。或因噴施液掉落於土壤而殘留之故，因此葉面噴施不宜連年施行。
5．土壤熱水可溶性硼含量亦反應土壤施硼量，所施硼酸有自表土向底土移動之趨勢。

並列摘要

Abnormal fruit of ponkang and tungkang in Tunghsi orchard were investigated in October, 1976, showing smaller size, thicker peel, less juicy and much harder than that of normal fruits. The leaf and peel B content were about 10ppm which were much lower than the normal range of boron content (B 25-150ppm) as indicated by the Chapman's standard. The cause of the abnormal fruits was expected to be boron deficiency. Therefore, a field experiment was layed out in order to clarify the effect and method of boron application with the following treatments: (1) Control, no boron applicated, (2) Boric acid 40g/tree, by soil application, (3) Boric acid 120g/tree, by soil application, (4) 0.3% boric acid solution, by foliar spray twice a year, (5) Boric acid 40g/tree plus foliar spray, (6) Boric acid 40g/tree plus straw mulching. The leaf and soil boron contents with seasonal sampling were analyzed. The experimental results obtained were summarized as follows.
1. The hot water soluble B contents in the experimental field were low, that is, 0.15ppm in surface soil (0-15cm) and 0.10ppm in subsoil (15-30cm). The leaf and peel B contents were about 10ppm when the boron deficiency of citrus occurred in the dry year. It was 20ppm in leaves and 14ppm in peels when the precipitation was abundant during the year and no occurrence of boron deficiency was observed.
2. The B con tent in leaves from nonfruiting twigs of spring cycle increased with leaf age, that is, the B content was higher in old leaves than in young leaves. However, the B content was always low either in old leaves or in young leaves when boron was deficient in citrus trees.
3. Soil application of boric acid 40-120g/tree on citrus orchard with medium textured soil and 10-year-old trees was effective for correction of boron deficiency and its residual effect was maintained for more than 4 years. It was found that the P content in leaves decreased as the application amount of boric acid was increased. There was a significant negative correlation between the P and B content in leaves in the year of boric acid application. Boric acid 50g/tree by soil application every four years was recommended for boron deficient orchards under the same soil conditions.
4. Foliar spray of 0.3% boric acid solution was also effective, however, considerable amount of boron were accumulated in the soil which was fallen from the continuous yearly-spray of boron. So, it is suggested that the foliar spray should not be done every year.