Effects of Organic and Inorganic Fertilizers on the Growth of Rice Plants under Different Light Intensities

Abstract

Effects of organic fertilizer (liquid concentrated protein extract ; N : 9.2%, P₂O₅ : 2.4%, K₂O : 3.1%) and inorganic fertilizer on the growth of rice plants were studied under various light intensities. Rice seedlings (cultivar ; Nipponbare) of 2.5-leaf age were transplanted in 1 /2000a Wagner pots, and were fertilized with the water solution of organic (organic plot) and inorganic fertilizers (inorganic plot), every ten days after transplanting, under 0 and 50% shading from transplanting until the flag leaf expansion. The amounts of N, P₂O₅ and K₂O (460, 120, 150 mg per pot, respectively) applied was adjusted to be the same. Leaf emergence rates of main stem were affected by light intensity, but not by fertilizing. More tillers emerged in the inorganic plot than organic plot without shading. Under 50% shading, the organic plot seemed to produce more tillers than the inorganic plot. Photosynthetic rate, leaf color (SPAD) value and N content of flag leaf were higher in inorganic plot than in organic plot. Top dry matters at the stage of flag leaf expansion were heavier in inorganic plot under no shading, and heavier in the organic plot under 50% shading. Root dry matter at the same stage was heavier in organic plot under both light intensities.