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Four experiments were conducted to investigate sowing rates (1, 2, 3, or 4g. seeds.mˉ2) effects on lettuce transplant performance, to improve growth and yield of lettuce by populations, plot and furrow cultivations under rainfalls and supplementary irrigation, to boost drought resistance by using either GA3 or NAA rates of 0, 50, 75 or 100 mg.lˉ1. Results of experiment 1 showed that 2 g seeds.mˉ2 was the most suitable rate for the high performance transplant productions. It gave transplant numbers of 738.3 in which large, medium and small size transplants constituted 18, 36, and 46%, respectively. Results of experiment 2 revealed that the possibility of producing lettuce under rainfalls only and supplementary irrigation is not required, furrow cultivation was superior to that of plot. It exceeded the latter by 15.4% in term of yield, high population (28 plants.mˉ2) yielded ( 109.1% ) more than that of ( 14 plnt.mˉ2),however it tended to reduce the weight of individual head. The highest yield ( 8.08 kg.mˉ2) was obtained from furrow high population interactions with either rainfalls or supplementary irrigation. Experiment 3 results confirmed that GA3 highly improved the hearting process, particularly 100mg.l-1 treatment which resulted in the highest yield(5.9 kg.mˉ2), bulk density ( 0.2 g.cmˉ3), head size(2150 cm3) and individual head weight (423.3 g). The final experiment 4 results showed that NAA rate of 50 mg.lˉ1 was the most effective treatment as it gave the highest yield ( 3.12 kg.mˉ2), and weight of single head (403.3 g). However NAA rates were inferior to these of GA3. INTRODUCTION Lettuce is a very popular vegetable crop grown in Iraq and its production facing many problems commencing with its seed germination and their inhibition by extremes temperature and light intensity ( Gray, 1977; Cantliffe et al., 1984 and Wein,1997). Lettuce heading highly influence by ambient environments and cultural practices as their negative effects display on plant stature and performance which reduce the marketable yield owing to physiological disorders and deformed heads( Wurr et al.,1987; Wurr and Fellows,1991; Quaile and Presnell,1991 and Misaghi et al.,1992). Irrigation is one of the most effective cultural practice in vegetable production especially in lettuce owing to their shallow effective root system (30 cm ) depth ( Jackson, 1995; Schwarz et al., 1995 and Gallardo et al., 1996). Mosul city is located on 360o, 42′′ latitude and Altitude of 230m , it receives an actual rainfalls (381 mm.yearˉ1), however, there are uneven yearly rain distribution and also among raining months in the season which is usually commence on November and ends on May(Guest,1966). Mosul suffer from water shortages owing to the topography which makes water conduction be very difficult and cost much besides its scarcity , Received 23/8/2005 Accepted 4/1/2006 Mesopotamia J. of Agric (ISSN 1815-316 X) Vol. ( 33 ) NO ( 4 ) 2005 and therefore four experiments were included to investigate lettuce productions through attempts to produce transplants and grow lettuce under rainfalls and complementary irrigation to find if there are any possibilities to produce this crop under rainfalls by manipulating some cultural practices. MATERIALS AND METHODS Four experiments was carried out in Mosul City which is located on north latitude of 36o,42" and Altitude of 230m to investigate the possibility of producing lettuce under the available rainfalls during fall growing seasons of 2001-2002 and 2003-2004 through simulating cultural practices and use of some growth regulators, and thus we have conducted the following experiments . Experiment 1: Production of lettuce ( Lactuca sativa var longifolia Local cv.) transplants under rainfalls: This experiment was carried out during 2001-2002 fall growing season at Yarimja vegetable growing farms, Yarimja, Mosul city, IRAQ. Largest headed plants of good stature were selected from the previous fall season (200-2001) and cut off 5 cm above soil surface at harvesting , while other undesired plants were pulled with their roots out of the soil. Shoots were sprouted at nodes on the remained stem cuts and new small plants were formed, they were fertilized by NPK (27, 27,0) and weeds were manually eradicated .Finally seeds were collected and then kept at dry place to use them in the next season. A randomized Complete Block Design (RCBD) was used to include four sowing rates( 1, 2, 3 or 4 g. seeds. mˉ2) replicated four times, each replicate was represented by a plot of 1m2. The given seeds of each plot were equally distributed on 9 lines 10cm apart , and therefore this experiments had 16 plots. A laboratory seed germination at 20Co showed a germination percentage of (95%). Soil was dissected in to 16 plots . A sheep manure (0.1 m.mˉ2) and nitrogen fertilizer urea ( 25g.mˉ2) were applied before sowing on November,1 ,2000 .Seedlings were harvested on December, 20 , 2001. The harvested transplants were put into three size categories (large, medium and small) then for each category seedling numbers, seedling lengths, root length, stem lengths, leaf numbers , leaf fresh weights, root fresh weights, stem fresh weighs and weight of fresh transplants were measured . Leaves , roots and stems were oven dried at 60 Co for 72 h and the weighed to calculate their dry matter percentages. Soil analysis (table 1, 2) was carried out in agricultural college, soil department. Were as meteorological data (figure 1, 2) was obtained from Al-Rashidia station, Mosul, Iraq. Table (1): Physical analysis for loam soil of Yarimja field. Soil field Soil bulk density Particle sizes (%) Soil separation capacity (%) (g.cmˉ3) (g.Kgˉ1 0.21 1.58 159.8 Clay

WATER RELATIONS IN LETTUCE(Lactuca sativa L.Var longiflia)