Abstract
A field experiment was conducted during two spring seasons of 2002 and 2003, to study the possibility of decreasing water stress decay and improved growth , yield and quality of potato plants cv. Desiree by using liquid paraffin as antitranspirant and Naphthalen acetic acid as growth regulator. Plants were exposured to water stress twice by no water supply till plant wilting during tubers formation period 51 and 82 days after planting date. Liquid paraffin at two concentration ( 0 and 2 % ) were applied twice after 53 and 84 days of planting ,and naphthalene acetic acid at two concentration ( 0, and 40 mg / L. ) were applied twice after 48 and 78 days of planting .The study included 8 treatments laid out in factorial experiment within split–plot design replicated three times .The results can be summarized as follows : Exposuring potato plants to water stress caused a significant decreases in total water content (TWC) in leaves , leaf area , dry weight of plant , tuber number per plant , tuber weight , and plant and marketable yield .However ; a significant increases was observed in dry matter percentage , total soluble solids (TSS) and percentage of loss and decayed tubers after storage .Foliar application of liquid paraffin at 2 % significantly increased the TWC and total chlorophyll content in leaves , tubers number , tuber weight , plant and marketable yield . Foliar application of NAA by 40 mg./ L. significantly increased the marketable yield and the total soluble solids percentage in tubers. The interaction treatments between liquid paraffin and NAA , significantly decreased the damage effect of water stress on stressed plants and improved growth and yield of unstressed plants , however the spraying of liquid paraffin and NAA decreased the differences between water stressed and non-water stressed plants in many growth and yield characters .
