Effect of foliar applied phosphatic fertilizer on absorption pathways, yield and quality of sweet persimmon

Pot and field experiments were conducted to identify nutrient absorption pathways, growth, yield and quality of sweet persimmon using ³²P tagged fermented mono-calcium di-hydrogen phosphate (FMCP) and normal FMCP fertilizer, respectively. In pot experiment, lower surface treated leaf absorbed higher amount of radionuclide phosphorus than upper surface treated leaf and phosphorus absorption increased with the increase in duration. The highest radioactive phosphorus absorption obtained was 8.88 × 10⁴ and 3.57 × 10⁴ Bq/g dry weight of leaf against dorsal and ventral treated leaf surfaces at 96 h after fertilizer application. During experimentation, stomata were closed from 2 to 10 h after application of FMCP fertilizer and nutrient absorption was higher in the lower surface than the upper surface. As a result, phosphorus was absorbed through cuticle by diffusing in aqueous pores in lower surface of leaf. Alternate day and night (24–96 h), lower surface also performed higher amount of phosphorus absorption than upper surface of leaf due to stomatal activity and aqueous pores because lower surface contains higher number of stomata than upper surface of sweet persimmon. It may be concluded that aqueous pores as well as stomata can be important pathways for the absorption of foliar applied FMCP fertilizer. In field experiment, foliar application of normal FMCP fertilizer increased the vegetative growth, number of effective flowering buds and decreased insect–disease infestation of sweet persimmon over control. Sweet persimmon yield increased due to the fact of decreasing trend of fruit dropping by foliar fertilization. Maximum fruit number (1110 and 1449 per tree) was observed in T₄ (foliar spray @ 7.5 ppm P of FMCP fertilizer) and T₅ (alternate foliar spray of 10 and 7.5 ppm P of FMCP fertilizer) treatments in 2005 and 2006, respectively. In T₄ and T₅ treatments, the average fruit yield increased by 153.0 and 211.4 kg tree⁻¹ in 2005 and 2006 over control, respectively. FMCP fertilizer gave maximum fruit yield in T₄ and T₅ treatments in 2005 and 2006, respectively and it differed from other foliar treatments including control. Treatment T₅ increased fruit hardness (2.32 kg/Ø 5 mm), ⁰brix content (14.0%) and reduced acidity (0.018%) in 2005. These results allow us to infer that foliar application of FMCP fertilizer was not only augmenting the fruit yield of sweet persimmon but also improved the quality of produce.