行政院農業委員會台南區農業改良場  研究彙報第1號

大豆植物體內水分含量對其生育及子實之影響

蘇匡基 施宗禮

摘  要

為確立利用植物體內水分的變異為灌溉指標的技術,於民國56年秋作與民國57年春作,用大豆品種愛家豆(晚生),台大高雄5號(中生)及十石(早生)等三品種調查葉片相對膨壓度之高低對於大豆生育及產量之影響結果摘述如下:

(1)大豆葉片相對膨壓度,依採取時間,葉片之老嫩,及品種之不同在同一土壤水分及氣象環境下表示不同數值。即白天以日出時相對膨壓度最高,隨太陽之上昇相對膨壓度減低到下午1-2點間最低,以後逐漸恢復高值。葉片近於頂部之展開葉較近於基部的老葉其相對膨壓度稍高。品種間以愛家豆,其相對膨壓度較其他品種為高而變幅(Diurnal fluctuation)較小。

(2)相對膨壓度與土壤水分含量間其相關係數僅(+)0.4391~(+)0.5684而已,但氣象因素,如與氣溫、相對濕度或Pan蒸發量間具有高的相關關係,其相關係數各(-)0.7788,(+)0.6955及(-)0.8002。而此等係數均在1%水準顯著,因此相對膨壓度似受土壤水分含量影響較少而氣象因素的影響較大。

(3)下午1-2點間大豆葉片相對膨壓度保持75%以上時較70%以下時,其株高、分枝數、莢果數、種子千粒重及種子產量均增高,生育日數亦會增加。以相對膨壓度為依據的灌溉指標,與慣行的土壤水分含量或蒸發盤蒸發量為依據的灌溉處理間。其生育及產量並無顯著的差異。

總而言之,利用相對膨壓度為灌溉指標的技術,由於採樣時間、葉位、品種間的變異大,費時又費工,其實用價值尚不及目前慣用的土壤水分蒸發量為指標的灌溉技術。


Effects of Internal Water Content of Plant on the Growth and Yield of Soybean

Kuang-chi Su

Summary

       To establish the irrigation criterion according to variation of internal water contents, the study on effects of relative turgidity of soybean leaves was conducted in Fall 1967 and Spring 1968.  Late variety, Acadian, medium variety Taita-Kaohsiong No. 5 and early variety Hsih-hsih were used.  The results were as follows:

1. The value of relative turgidity of soybean leaves showed significant variation according to the times of sampling, age of leaves, and varieties. On the daytime, the value was maximum at sunrise, then decreased toward the minimum at 1 to 2 pm, and increased again toward sunset. The leaves near the top showed higher relative turgid than the leaves near the ground.  Variety Acadian showed higher value and less fluctuation than the other varieties.

2. The correlation coefficient between relative turgidity and soil moisture content was (+) 0.4391 to (+) 0.5684.  Relative turgidity was related to atmospheric condition. The correlation coefficients with air temperature, relative humidity, and pan evaporation were (-) 0.7788, (+) 0.6955 and (-) 0.8002, respectively.  These results indicated atmospheric condition has more effect in regulating the internal water balance of plant than the soil moisture condition.

3. Soybean grown under high relative turgidity (above 75% between 1 to 2 pm) showed higher plant height, number of branch, number of matured pod, 1,000 seed weight, and grain yield than the lower relative turgidity.  There were no significant different on growth and yield between different criterions as relative turgidity, soil moisture, or pan evaporation.

Since the value of relative turgidity were varied according to time of sampling, age of leaves, and varieties, and the procedure was time and labor costing, using relative turgidity for scheduling soybean irrigation may not exceed the conventional soil moisture criterion or evaporation criterion.



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