PHOSPHORUS, MANGANESE AND IRON RATIOS IN GRAPEVINE (VITIS VINIFERA L.) LEAVES ON ACID AND CALCAREOUS SOILS

Abstract

Influence of soil reaction on phosphorus (P), manganese (Mn) and iron (Fe) ratios in grapevine leaves was investigated during 2007 and 2008 in northwestern Croatia. The trial was set up on three vitisol subtypes: dystric cambisol (pHKCl 3.95), pseudogley (pHKCl 4.68) and rendzina on marl (pHKCl 7.35). Leaf samples were taken three times during the vegetation period, flowering, during verasion, and at the end of the growing period. The lowest P concentration was determined at flowering stage in 2007 on acid soil (0.15 % P DM), while the highest P concentration was determined in the same year at the harvest time on alkaline soil (0.60 % P DM). The highest Mn concentration (536.7 mg Mn kg-1 DM) in grapevine leaves was observed at the harvest time 2007 on very acid soil and were 3 to 5 times higher than optimal concentration (30-100 mg Mn kg-1 DM). The lowest Mn concentration was determined at the flowering stage 2008 on alkaline soil (22.4 mg Mn kg-1 DM). Smaller amounts of Fe in calcareous soil compared to acid soils were determined at all vegetation phases in 2007, while in 2008 the same trend was recorded only at harvest. In both years of investigation on acid soils an extremely unfavorable P:Mn ratio was determined and it ranged between 3.12 to 24.31. Alkaline soil P:Mn ratio was satisfactory in all sampling times in 2007, while during 2008 was significantly greater than the optimum (optimum P:Mn 25-50). Significantly more favorable P:Fe ratio in both years of research in all phases of the vegetation was determined on calcareous soil (21.3-38.45) compared to acid soils (9.17-31.94). Favorable Fe:Mn ratio was determined only on calcareous soil in 2007 year at harvest (1.38), while in 2008 this ratio was unfavorable in all phases of vegetation on acid (0.25-0.76) and calcareous soils (3.07-8.83).