這是個眾多自養生物成長和吸收的典型的廣義模式。基於上面的圖二,從園藝學的觀點來看,提供不受限的環境(綠色方塊~即良好的目標範圍)能提高水草的產量,因為濃度的目標範圍很寬廣,而且在此範圍內的水草成長速率也比較高。對大部分的園藝家而言,長時間持續維持一個固定的濃度很困難也不切實際,但是維持一個可用的範圍就很容易達成。限制水草的營養,在探討個別品種的差異與反應時是有用的,但是這對於一個穩定的栽培而言絕非是個好方法。在抑制作用發生之前,不受限的營養與光照強度必需達到相當高的程度。從水草的角度來看,許多營養的抑制濃度在哪其實並不是很清楚,更何況這也和動物(例如魚類和無脊椎動物)的致死濃度息息相關。這個濃度範圍提供了一個很大的可用範圍,相當容易就能夠達成,並且提供在水草栽培上的穩定濃度。限制的作法其實範圍是很窄小的,而且從實際面來看,很不容易提供一個穩定的濃度範圍,況且從初始與維持劑量來看,也很難不發生錯誤。由於光照會促進水草的吸收速率,所以只要光照強度超過了補償點的較低光照強度下,此時的低營養濃度比較不會出錯。一般來說,在接近光補償點的低光照強度下,不受限營養的濃度範圍也較低。根據Van等人1986年針對三種水草以及在Tropica針對鹿角苔所做的研究 ,都發現相同的結果。由園藝的角度來看這兩個研究,不受限的營養範圍在低光照強度下,是個比較好且穩定的栽培方式,水草也更強壯。
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Translation by Erich L.T. Sia