Effect of trace elements Zn, B, Mg and Cu on the growth and sporulation of Pyricularia oryzae, the causal organism of blast disease of rice

Blast is one of the most common disease of the Rice crop caused by Pyricularia oryzae. Blast of Rice is a recurrent problem of Rice producing countries declines productivity drastically. Mycelium growth and sporulation of P. oryzae is depend upon many factors i.e. humidity, temperature, availability of nutrients etc. Like other fungi P. oryzae also requires some nutrients in very minute quantity for their physiological and metabolic activities. Regulating these micronutrients or trace elements we can control the growth and spore production in P. oryzae. In this paper, we studied effect of four trace elements i.e. Zinc (Zn), Boron (B), Magnesium (Mg) and Copper (Cu) on growth and sporulation of P. oryzae. Zinc, Boron and Copper are most effective and promote growth and sporulation at 2 ppm (parts per million) concentration when we increased concentration of these elements in the medium, growth and sporulation decreased .On the other hand less growth and sporulation reported in the absence of Magnesium. Minute quantity of Magnesium is required for optimum growth i.e. 2 ppm. after this increasing concentration of Magnesium is not significant.

Low Mass Hydrogen Envelopes and the DB Gap

The existence of a gap in the distribution of helium atmosphere white dwarfs at the effective temperature interval 30,000 K ≤ Te ≤ 45,000 K is well documented (Wesemael, Green and Liebert 1985; Liebert et al 1986; Green and Liebert 1987).To explain the presence of this gap and other variations of the non-DA to DA ratio, it has been proposed (Fontaine and Wesemael 1987; Liebert, Fontaine and Wesemael 1987) that the helium-rich PG 1159 stars are the progenitors of essentially all white dwarfs. Some minute quantity of hydrogen of total mass, MH, is assumed to be mixed in the outer helium envelope, and settle upward as the star cools from the PG 1159 stage. Eventually enough hydrogen is at the surface to make the star appear a DA. The star has to become DA before it cools down to ≈ 45,000 K and cools to ≈ 30,000 K as a DA. At this temperature, depending on MH, the underlying helium convection zone may break into the hydrogen layer, diluting it and making the star a DB.

Constituents of the liverwort Lophocolea heterophylla

From Lophocolea heterophylla sesquiterpene hydrocarbons β-barbatene, ent-β-selinene, cuparene, calacorene, calamenene and cadalene were obtained; α-barbatene is probably an artifact. ent-Isoalantolactone is the main sesquiterpenoid component. The characteristic smell of the plant is due to the presence of a minute quantity of the alcohol C12H20O, not characterized in details. Nonacosan-10-one and esterified nonacosan-10-ol are present in the lipid part of extract, in addition to „normal" components (n-alkanes, cerides).