Greinasafn: Physiological properties of plants affecting ice-encasement tolerance

Physiological properties of plants affecting ice-encasement tolerance


Höfundur	Útgefandi	Útgáfuár	Útgáfustaður
Andrews Chris J., Pomeroy M. Keith	Búnaðarfélag Íslands, Bændaskólinn á Hvanneyri, Rannsóknastofnun landbúnaðarins, Rannsóknastöð Skógræktar ríkisins, Tilraunastöð háskólans í meinafræði, Veiðimálastofnun	1989	Reykjavík

Rit	Árgangur	Tölublað	Bls.
Búvísindi		2	41-51

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ABSTRACT

The process of hardening, and conditions leading to ice-encasement damage in winter cereals are discussed. During the anaerobic respiration in ice, CO2, ethanol and lactate are produced. Experiments indicate that in ice CO2 is produced to sufficient concentrations to account for death of plants, and ethanol enhances the toxicity of CO2. Low temperature flooding prior to ice encasement increases the tolerance to ice. Ice encasement in light allows greater survival in comparison to encasement in dark. Balances between anaerobic metabolite accumulation and carbohydrate utilization within plant crowns in ice have been established. In field experiments, late plantings have survived severe ice encasement better than normal plantings. Procedures are discussed for the controlled testing of ice-encasement tolerance.

Key words: anaerobic metabolites, anaerobic respiration, flooding, ice encasement.

YFIRLIT

Áhrif lífeðlisfræðilegra þátta á svellþol jurta

Rætt er um hörðnun og svellþol í vetrarkorni. Við loftfirrða öndun í svellum myndast CO2, etanól og mjólkursýra. Í svellatilraunum myndast nægilegt magn af CO2 til að drepa plönturnar, en ethanol eykur eitrunaráhrif CO2. Lághitaflóð á undan svellun auka svellþol vetrarkorns. Svellun í ljósi dregur úr skemmdum samanborið við svellun í myrkri. Samsöfnun efna, sem myndast við loftfirrða öndun, hefur verið borin saman við hvarf sykra úr plöntum, sem umluknar eru svelli. Í akurtilraunum lifa plöntur sem er sáð seint að hausti betur en snemmsáðar plöntur. Rætt er um aðferðir til prófunar á svellþoli.

INTRODUCTION

Overwintering crop plants in northern areas are subject to a wide range of environmental stresses which may destroy them, or reduce their vigour sufficiently to lead to a subsequent reduction in economic yield. These stresses are associated directly or indirectly with low temperature and include freezing, desiccation, low temperature flooding, ice encasement and snow molds (Pomeroy and Andrews, 1989). Some of these stresses may influence overwintering plants singly, or in combination, while others may affect the plants sequentially with accumulative damage and yield reductions. Winter stresses can be avoided by the use of spring planted crops but frequently the economic yield of the spring planted type is too low to be acceptable to the producer when the possibility exists of obtaining the larger yield from a successful overwintered crop.

In northern maritime areas with high winter precipitation and temperatures which may fluctuate around the freezing point, ice encasement can become the most significant form of winter damage to low-growing rosette type plants (Sjøseth, 1959, 1964). In these conditions, the snow layer covering the plants may partially melt, or rain may fall on the snow and percolate through to the soil surface where water accumulates to form ice when the temperature returns to its winter norm. This condition is always stressful to plants: different species vary in their tolerance to it, and each species may vary in its tolerance to it according to its physiological state at the onset of the ice, and the severity of the ice encasement stress itself. This paper will explore these relationships influencing survival in ice encasement and will discuss the mechanisms of damage to plants in ice. In most cases, reference will be made to experimental work with winter cereals, but similar concepts frequently apply to forage grasses and legumes.