conservation tillage, a fast growing practice in iran, is considered as a means to achieve sustainability in agricultural systems. this study was carried out to determine the effect of tillage systems (no-tillage, minimum tillage and conventional tillage ) on yield and yield components of three irrigated wheat varieties. the field experiment was conducted at the experimental station of the univ...

The order of discovery can have a profound effect upon the way in which we think about the function of a gene. In E. coli, recA is nearly essential for cell survival in the presence of DNA damage. However, recA was originally identified, as a gene required to obtain recombinant DNA molecules in conjugating bacteria. As a result, it has been frequently assumed that recA promotes the survival of ...