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INFLUENCE OF SOIL PROPERTIES ON PHYTOTOXICITY OF 4–AMlNO‐3,5,6–TRICHLOROPICOLINIC ACID (PICLORAM)
Author(s) -
GROVER R.
Publication year - 1968
Publication title -
weed research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.693
H-Index - 74
eISSN - 1365-3180
pISSN - 0043-1737
DOI - 10.1111/j.1365-3180.1968.tb01425.x
Subject(s) - picloram , chemistry , loam , organic matter , helianthus annuus , phytotoxicity , cation exchange capacity , soil ph , soil water , environmental chemistry , agronomy , sunflower , soil science , biology , environmental science , organic chemistry
Summary. Effective dosages of picloram (4–amino‐3,5,6–trichloropicolinic acid) required to reduce fresh weight of sunflowers ( Helianthus annuus L. var. Menonite) were determined for seven Saskatchewan soils under controlled environmental conditions. The relationships between ED 50 value and clay content, organic matter content and cation exchange capacity were evaluated by correlation and regression analysis for possible usefulness in predicting dose requirements. ED 50 values were also determined for Weyburn loam and in culture solutions adjusted to various pH levels. There Was no significant correlation between ED 50 values of picloram and soil clay content or cation exchange capacity. ED 50 values were highly correlated with soil organic matter content, and they increased as the soil pH was lowered or raised from pH 6.5. The increase in ED 50 values in the acidic range was attributed to adsorption of the unionized molecules of picloram on the organic matter in the soil. The increase in ED 50 values in the alkaline range may be mainly due to reduced uptake of the ionized acid by plant roots.