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The study sought to identify the effects of deficit irrigation on the yield and quality of tomatoes. A greenhouse experiment was conducted during the summer of 1999 and repeated in winter 2000 using nine treatments. Two threshold soil moisture deficit levels, 65% and 80% depletion of plant available water, were factorially combined with 5 irrigation timing patterns: (i) no water stress (ii) stress throughout season, (iii) stress during flowering and fruit set, (iv) stress during fruit growth and (v) stress during fruit ripening. The treatments were set up in a randomized complete block design with 4 replicates. Crop yields, maximum and minimum equatorial diameter and fruit heights were measured. The quality parameters included: soluble solids, pH and the color index. Water stress throughout the growing season significantly reduced yield and fruit size but increased the level of soluble solids. No water stress throughout the growing season or stress only during the flowering stage provided highest tomato yield.

Water management for the irrigation of containerized production remains a task reserved to a highly qualified personnel. Without proper instruments to determine the actual water needs, nursery crops can face growth losses of 20 to 30%. / Reviewing the different methods that are used in field production, tensiometer have shown the greatest potential of adaptation to potted plants. / Tests on the utilization of tensiometer were realized on two peat-vermiculite substrates, using two types of porous cup (1 bat--standard flow and 1 bar--high flow). The instruments were tested while permanently fixed in the growing medium, and temporarily fixed for three hours in the growing medium. / The results show that the instruments give excellent measurements for normal condition of growth, requiring saturation level between 50 and 100%, and that for both mode of operation. / Preferably, the choice of the instrument should be based on the hydraulic characteristics of the substrate. Little difference has been found using both instrument in the substrate 1, but in substrate 2 however, the high flow porous cups have given better response. The high flow cups have higher porosity and bigger pores that suit better substrate 2, which is made of coarser particles.

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Frequent drainage and aeration problems occur in blueberry plantings on acid peats (pH 3.0 to pH 4.2) of British Columbia during a part of the growing season. The effect of waterlogging, pH, and form of N were studied under greenhouse conditions. Using one year old plants of Bluecrop blueberry, a split plot design was employed with two water tables for main plots and a factorial combination of 4 pH levels and 3 levels each of ammonium and nitrate N (20, 40, and 60 lbs. N/acre). An unfertilized check treatment was also included as a treatment. Growth records and leaf analysis showed that poor aeration under waterlogged conditions exhibited characters symptomatic of poor nutrition. Sparse leaf growth, smaller leaves with severe yellowing and premature leaf abscission were observed in the high water table treatments. Leaf analysis revealed highly significant differences in foliar N, P, K, Ca, Mg, and Fe levels. There was also a greater growth response to ammonium N and nitrate N. Higher levels of nitrate N (40, and 60 lbs. N/acre) caused severe leaf scorch. Although higher levels of ammonium N (40, and 60 lbs. N/acre) gave better growth response, growth was prolonged and fall leaf drop and wood maturation were delayed. Plants receiving 60 lbs. N/acre as ammonium N showed symptoms of dieback in the following spring. Although pH had very little effect on leaf nutrient composition, growth appeared to be better at a pH level of around 4.2. / Land and Food Systems, Faculty of / Graduate

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