Effect Of Vermicom Post, Phosphorous Nano-Fertilizer And Humic Acid On The Activity Of Alkaline Phosphatase Enzyme And Its Kinetic Parameters

Abstract

A field experiment was inducted during autumn season of 2020 in one of the fields of Afak district - Al-Diwaniyah governorate / Iraq to investigate the effect of vermicompost, phosphorous nano-fertilizer and humic acid on the activity of alkaline phosphatase enzyme and its kinetic parameters at the flowering and full maturity stages of maize. Randomized Complete Blocks Design was used at three replications. The experiment included 14 treatments: {Control (C), Vermicompost at 4 ton ha-1)V), phosphorous nano fertilizer at 5 and kg ha-1 (nP1 and nP2), humic acid at 20 and 40 kg ha-1 (H1 and H2), VnP1, VnP2, VH1, VH2, H1nP1, H1nP2, H2nP1 and H2nP2}. The results showed that theV treatment hadahighest mean of alkaline phosphatase activity (528.1μg P-nitrophenol g-1 soil 1h-1) and of Vmax(194.8μg þ-nitrophenol g-1 soil 1h-1) at the flowering stage only, and the lowest means of Km(0.2403 and 0.2367mM) at the flowering and full maturity stages respectively. The nP2 treatment achieved the highest means of alkaline phosphatase activity (690.6 and 635.2μg P-nitrophenol g-1 soil 1h-1)at flowering and full maturity stages respectivelyand Vmax(187.5 μg P-nitrophenol g-1 soil 1h-1)at flowering stage only, whereas the nP1 treatment had the lowest means of Km (0.2527 and 0.3087) at the flowering and full maturity stages respectively.Further, the H1 treatment gave the highest means of alkaline phosphatase activity (563.3 and 515.2μg P-nitrophenol g-1 soil 1h-1) at flowering and full maturity stages respectively and Vmax(194.8 μg P-nitrophenol g-1 soil 1h-1) at flowering stage only. Further, the H1 and H2 treatment achieved the lowest means of Km (0.2483 and 0.2690mM) at the flowering and full maturity stages respectively.The VH1 treatment had the highest means of alkaline phosphatase activity (754.5 and 736.4 μg P-nitrophenol g-1 soil 1h-1)at flowering and full maturity stages respectively and Vmax (192.3 μg þ-nitrophenol g-1 soil 1h-1)at flowering stage only. In addition to, VH1treatment gave the lowest means of Km (0.2177 and 0.2373 mM) at flowering and full maturity stages.