Effect of Fertilizer-N and Herbicides on the Growth and N Content of Sunflower
1976
Sameni, A. M. | Maftoun, M. | Hojjati, S. M. | Sheibany, B.
Little is known about herbicide-N fertilizer combinations with respect to the growth and mineral composition of sunflower (Helianthus annuus L.). The present study was undertaken to evaluate the effect of prometryn (2,4-bis(isopropylamino)-6-(methylthio)-s-triazine), terbutryn (2-(tert-butylamino)-4-(ethylamino)-6-(methylthio)-striazine), trifluralin (a,a,a-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine), and N level on the growth and N uptake by this crop. Sunflower was grown in greenhouse for 60 days in soil to which was added various levels of N and herbicides. Dry matter yields, N concentration and N uptake were determined. Low N levels significantly increased stem diameter and chlorophyll content of leaves as compared to the no N level. Nitrogen application above 25 ppm did not increase stem diameter. All N-treated plants produced more dry matter and contained significantly higher N than untreated seedlings. Prometryntreated seedlings developed chlorotic symptoms, causing plant death. Nitrogen uptake increased with 1 ppm terbutryn, but 2 ppm terbutryn increased N concentration and uptake but decreased plant height, stem diameter, chlorophyll content, and total plant weight of sunflower. The tendency for terbutryn to increase N concentration was more pronounced when sunflower was under N stress. Trifluralin did not significantly increase top dry weight or N uptake, nor did it interact with N treatments.
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