RESUMEN
Adsorption of atrazine was studied on two Vertisols and two Alfisols varying in their physicochemical properties. Soils were equilibrated with various concentrations of atrazine using batch techniques. Adsorption affinity for atrazine was approximated by Freundlich constant (Kf), which is a measure of the strength or degree of adsorption. Kd values were calculated for atrazine despite some non-linearity in adsorption on both Vertisols and Alfisols. The Kd values are greater for Vertisols than Alfisols and increased with organic carbon content. Correlations were worked out between extent of adsorption and soil properties and were positively correlated with organic carbon (r = 0.688), clay content ( r = 0.712) and clay + organic carbon (r = 0.708). KOC values were calculated taking into account the organic carbon content for both Vertisols and Alfisols.
RESUMEN
Flowering phenology and reproductive biology of Rhynchosia beddomei, an endemic medicinal plant of Tirumala hills was studied in the natural habitat in the year 2010-11. Flowering was initiated in December 1st week and continued up to end of March. Peak flowering was observed in 4th week of December and another small peak was also observed in February 2nd week. The flowers are yellow in colour and are arranged in axillary or terminal recemes. Maximum pollen germination was observed in 12.5% sucrose solution + BBM at the time of anthesis (between12 noon to 12. 30PM) and in 37.5% concentration at 3.00PM. Maximum pollen viability was observed at 11.30 AM in TTC and FCR tests. Pollen tube growth was maximum in 12.5% sucrose with BBM at 11.30 AM. Pollen were lipid rich and starch poor. Predominance of outcrossing was observed and was brought about by insects, particularly bees.