Smith G S, Cornforth I S, Henderson H V
Ruakura Soil and Plant Research Station, Ministry of Agriculture and Fisheries, Private Bag, Hamilton, New Zealand.
New Phytol. 1985 Nov;101(3):393-409. doi: 10.1111/j.1469-8137.1985.tb02846.x.
Critical leaf concentrations for deficiency of nitrogen, potassium, phosphorus, sulphur, and magnesium were estimated for perennial ryegrass (Lolium perenne L.) grown in sand culture. The values associated with a 10% reduction in dry matter yield were as follows (all results expressed as g kg DM except for the nitrate-nitrogen value which appears as μg DM): Kjeldahl-nitrogen 32; nitrate-nitrogen 500; potassium 28; phosphorus 2.1; sulphur 1.8; and magnesium 0.7. A major difference between the critical leaf concentrations estimated in this study and the tentative values published elsewhere was for potassium. Concentrations required in the shoot for near maximum growth were higher than previously reported. Differences in the nitrogen status of the plants probably account for this result. The depressing effect of potassium on the absorption of magnesium and calcium is discussed in relation to plant and animal nutrition. Sulphur was found to be inefficiently absorbed by phosphorus deficient plants despite non-limiting amounts of sulphur applied in the nutrient solution. A possible explanation for this effect may be linked to the observation that the transport of sulphate into the chloroplast was coupled with that of phosphate. The concentration of macroelements required in the nutrient solution to produce maximum shoot growth of perennial ryegrass was very much greater than that generally applied to plants grown in sand culture.
通过砂培种植多年生黑麦草（Lolium perenne L.），估算了氮、钾、磷、硫和镁缺乏时的临界叶片浓度。与干物质产量降低10%相关的值如下（除硝酸盐氮值以μg DM表示外，所有结果均以g kg DM表示）：凯氏氮32；硝酸盐氮500；钾28；磷2.1；硫1.8；镁0.7。本研究估算的临界叶片浓度与其他地方公布的暂定数值之间的主要差异在于钾。茎中实现接近最大生长所需的浓度高于先前报道的数值。植物氮素状况的差异可能是导致这一结果的原因。结合植物和动物营养，讨论了钾对镁和钙吸收的抑制作用。尽管营养液中施入了非限量的硫，但发现缺磷植物对硫的吸收效率较低。这种效应的一个可能解释可能与硫酸盐向叶绿体的转运与磷酸盐的转运相关这一观察结果有关。营养液中产生多年生黑麦草最大茎生长所需的大量元素浓度远高于通常用于砂培植物的浓度。
