A dynamic Model of Crop Growth Rate of Italian Ryegrass after Cutting

Italian ryegrass can produce plenty of
annual biomass in Arctic conditions.

Summary: The height and yield of Italian ryegrass was studied in North Finnish conditions. A dynamic model for the Crop Growth Rate was constructed in two stages: (a) model for the daily height increment and (b) regression model between height and yield. The explaining variables for the daily height increment were the growth rhythm and the theoretical daily dark respiration. The effect of temperature and incoming radiation on the Crop Growth Rate was discussed.

Introduction: The growth of grasses is preceded by the following three stages, (i) photosynthesis, (ii) translocation of carbohydrates, and (iii) biochemical process during cell division and enlargement. The energy for the first stage is provided by sunlight, and the energy for the second and third stages is released during respiration, from compounds photosynthesized earlier. Provided that the plant is kept at full turgor, then the respiration is mainly controlled by temperature (Utaaker, 1968). In most temperate grassland, the growth is largely limited by the periods of low temperature and drought (Spedding, 1971).

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Pohjonen, V. & Hari, P. 1973. A dynamic model of Crop Growth Rate of Italian ryegrass after cutting. Acta Agric. Scand. 23:121-126.

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Memoir 26.12.2016, updated 16.12.2021

This article with Pertti Hari was my first approach (manuscript 26.3.1973) to develop the concept for the proper time process inside cultivated plants (grasses and trees). This article was also my first peer reviewed article.