A Comparative Study of the Effects of Some Growth Regulators on the Biochemistry of Oryza sativa L.

A comparative study was made on the effects of indol-3yl-aceticacid (IAA), maleic hydrazide (MH), naphthalene acetic acid (NAA),and gibberellic acid (GA) at a concentration of 1o^-1 mg I^-1,on the growth and metabolism of Oryza sativa L., cv. Bhasamanik.All the growth substances excepting NAA caused promotion ofroot elongation and increased the number of roots formed buthad very little effect on shoot growth. NAA was found to havea retarding effect on the general growth of the plant, but alsoincreased the number of roots formed. At the concentration used IAA caused enhanced protein synthesisin parallel with increased root growth. However, with MH nosuch direct relationship could be observed between root growthand protein synthesis at the early stage, but stimulation ofroot growth was directly related to increased protein synthesisat the later stage. Despite the adverse effect of NAA on thegrowth of the plant, protein synthesis was not affected. Infact a general increase in the protein content of the plantwas observed. In plants treated with GA increased sugar contentand enhanced protein synthesis were noted. The levels of free amino acids were found to be affected markedlyby the application of the growth regulators. With NAA treatmentan accumulation of asparagine in the shoot and with GA an increasein the level of alanine in the root were noted. Aspartic aciddecreased in the roots, but increased in the shoots of treatedplants. Glutamic acid was lower in plants treated with IAA,MH, and NAA, while treatment with GA increased it in the shootat the tillering stage. In the shoots of IAA-, MH-, and NAA-treatedplants an increase in the quantity of serine was noted whereasunder the action of GA both serine and glycine decreased.