Anion proportion in the nutrient solution impacts the growth and nutrient status of anthurium (Anthurium andraeanum Linden ex. André.)

Abstract

"Anthurium is native to habitats characterized by low nutrient supply, however, when 33 cultivated, it demands a complete fertilization program. The objective of the present study was to 34 determine the effect of varying proportions of anions (nitrate (NO3 ), phosphate (H2PO4 ) and 35 sulphate (SO42) in the nutrient solution on the growth and nutrient status of container grown anthurium. The effect of the anion proportion was modeled using mixture analysis. Plant growth increased when fertigated with solutions containing an anion proportion of 0.78: 0.12: 0.10, 0.20 : 0.12 : 0.68 and 0.80 : 0.02 : 0.18. The contour plots showed that optimum response may be achieved in two areas, an area with high NO3 proportion (0.50-0.80) and an area with high SO4 , provided H2PO4 was high (0.09 – 0.12 for H2PO4 and 0.55-0.70 for SO42 ). The counter 41 plots indicate that high SO42 proportions combined with low NO3 and H2PO4 were detrimental 42 and that optimum growth depends not only on N concentration, as it may be attained at either high or low NO3 . Nitrogen and S concentration was higher in plants fertigated with high NO3 44 (0.55 – 0.80) and SO42- (0.40 -0.70) solutions. Shoot P was higher when plants were fertigated 45 with solutions of low (as long as NO3 was at proportions of 0.50 and SO42- at 0.35) or high 46 H2PO4 proportions (as long as SO42 proportion was at 0.35). At low concentration of S in the

shoot, increasing S resulted in increasing shoot N. however, further S increments in the shoot were associated with a decrease in N. Plants fertigated with the highest proportion of H2PO4 resulted in the lowest S concentrations despite some solutions contained high S04, suggesting that H2PO4 counteracted the uptake of SO4. Nitrogen and S were predominantly diverted to the roots in control plants, however, when plants were fed with both high SO4 and high H2PO4 solutions even more S was allocated to the roots, which explains the increased growth due to the lower S concentrations. In conclusion, the increased growth of anthurium was attained at either high or low NO3 proportion and it is able to cope with high SO42- by avoiding the transport of S to the shoot, decreasing SO4 intake, maintaining a favorable internal N/S and S/P proportion, 56 and increasing P tissue concentration."