AGRONOMIJAS VĒSTIS - Latvijas Lauksaimniecības universitāte

AGRONOMIJAS VĒSTIS (Latvian Journal of Agronomy), No.10, LLU, 2008Table 1. Height, phytomass dry matter (DM), and number of inflorescences (heads) of clover asaffected by exposure to contaminantsOptimal temperatureHigh temperatureTreatment*DMclover height, cm DMclover height, cmg/potg/potafteradaptationat the endof the testheadsperpotafteradaptationat the endof the testheadsperpotK+K 41.7 48.8 13.2 19 40.6 42.9 8.4 17K+R 40.3 44.6 12.7 21 39.5 42.6 9.5 15K+Cu 42.1 53.2 14.6 22 37.2 38.4 8.2 14K+Cd 39.5 45.5 12.1 19 37.4 38.7 8.7 21R+K 43.3 50.3 11.7 16 38.4 40.5 6.5 11R+R 40.2 45.3 10.8 15 39.0 40.3 7.4 14R+Cu 39.4 48.4 10.8 8 39.1 39.9 6.5 7R+Cd 42.7 48.7 9.9 10 40.6 42.7 7.5 12Cu+K 44.3 50.5 12.9 17 40.1 42.9 9.7 15Cu+R 46.1 53.6 14.4 23 41.4 43.7 7.0 7Cu+Cu 43.2 55.7 15.2 23 40.7 42.7 6.0 12Cu+Cd 44.2 54.4 12.5 17 41.3 44.4 9.4 16Cd+K 41.3 48.3 13.6 17 38.0 38.4 5.6 8Cd+R 42.2 53.4 16.0 22 44.1 49.4 7.8 7Cd+Cu 43.2 54.3 15.3 26 39.4 40.8 7.3 9Cd+Cd 41.0 47.7 12.8 18 38.4 38.9 7.0 12LSD 0.05 8.8 4.6 1.6 5.1 4.3 4.2 1.2 4.8*The first letter-mode of exposure during the adaptation stage. The second letter -during the main stage. K –Plants irrigated by water. R –Exposed to 6 ml H 2 SO 4 up to one litre diluted water solutionCd –Exposed to 0.16 mM 3 CdSO 4·8 H 2 O solution. Cu –During adaptation stage irrigated with 2 mMCuSO 4·5 H 2 O solution. During the main stage –irrigated with 4 mM CuSO 4·5 H 2 O solution.After the main stage clover flowered abundantly at optimal temperature, the plants weretaller than those that grew at higher temperature and were at the end of flowering stage. Plants grewthe tallest when at least once had been exposed to copper ions during the adaptation or main stage.At optimal temperature the highest increase in plant height was obtained when coppersulphate had been used during the adaptation and the main stage or during the first stage the plantshad been exposed to cadmium ions and during the second stage to acid or copper ions. This is alsoconfirmed by the dry matter data of clover overground phytomass. In these treatments phytomasswas significantly higher than in the check treatment where clover was irrigated by water. At highertemperature, significantly more phytomass was accumulated only in one case when in adaptationstage the plants were exposed to copper ions and in the main stage the plants were irrigated bywater. Phytomass significantly declined, unlike at lower temperature, when in adaptation and mainstages clover was exposed to copper ions. Our findings suggest that clover that grew at highertemperature produced less overground phytomass than that grown at optimal temperature, andcontaminants reduced overground phytomass of clover. The clover that grew at optimaltemperature formed more inflorescences than the clover that grew at higher temperature. Heavymetal salts with acid (R+Cu, Cu+R, Cd+R) had the greatest inhibiting effect on inflorescenceformation.After exposure of the clover plants in the main stage at optimal temperature to Cu ions, thecontent of photosynthetic pigments declined, except for the plants that had been exposed to acid inadaptation stage. Exposure to Cu and Cd ions in the adaptation stage did not exert any effect on thecontent of photosynthetic pigments (Fig. 1a). The content of chlorophyll a in the plants that grew athigh temperature increased only for the plants that had been exposed to Cu ions in the adaptationstage, however, the differences were not significant (Fig. 1b).177