effect of different irrigation and substrate on the growth and yield of lettuce (lactuca sativa l.cr paris island)

this experiment was conducted at research greenhouse of college of agriculture, ferdowsi university of mashhad in 1381-1382. the experiment was designed based on the splitted plots in the form of completely randomized design and in four replications. irrigation intervals were in three levels of 12, 4, and 2 times per day at primary plots, and three substrates of new perlite, used perlit, and rice bran at secondary plots. we used paris island as the lettuce seed. wet weight, dry weight, and height were influenced from irrigation interval. accordingly which 4- and 12-day irrigation intervals resulted in 466.39 and 386.94 g corresponding to highest and lowest dry weight, respectively and 12-day irrigation interval arose increase in lettuce height. significant differences for wet and dry weights were found under different substrates. high wet and dry weights were due to used perlit and rice bran substrates, respectively. there were no significant interactions between irrigation interval and substrate on all of the growth properties of lettuce.