Studies Regarding Biometric Characteristics of Lettuce (Lactuca sativa L.), Grown at Different Rates of Irrigation

Abstract

Many vegetable species are shallow-rooted and sensitive to mild water stress. A possibility for improving water use is better management of water application, but that’s require information on detailed seasonal changes in crop growth and on root distribution and root extraction of soil water that is not currently available for most vegetable crops. In lettuce, where the harvested part of the plant is the photosynthetic leaf area, it is especially important to maintain optimal growth through the application of water and nutrients (GALLARDO et al, 1996). The experiments were made in bifactorial sequences, in spring of year 2006, placed in the vegetable field glasshouse, from USAMV Cluj-Napoca. The main purpose was to study the watering regime influence on the yield level and the quality of lettuce. The experiment included drip irrigation and microsprinkler irrigation, with three irrigation water levels (60, 70 and 80 % from activ humidity interval). Harvested plants from each variant were evaluated immediately according to yield, plant height, head diameter, leaf number and dry matter. Plant weight (g), head diameter (cm) and plant height (cm) were measured by caliper rule and calculated as the average of measured values. The average leaf number per plant was calculated by counting the leaves, and the dry matter amount was found after drying at 85 o C in 48 hours. Data show that differences due to water regime, irrigation method and the interaction between water regime and irrigation methods were highly significant for both, yield and water use efficiency. At high irrigation levels (80% AHI), yield were high (30 t/ha with dripline) and decreased significantly (23,2 t/ha with microsprinklers) at low irrigation levels (60% AHI). We can draw the conclusion that for lettuce culture in protected area, the best irrigation method is drip irrigation. The microsprinklers with special sprayer are not giving the best results in protected area, because of higher evaporation losses, higher humidity, the wet foliage which increases the potential for diseases, recording a percent of 20 % perished plants. The significant increases in dry matter were found as parallel to irrigation water deficit and the highest and lowest dry matter were found at 60% AHI irrigation level and 80% from AHI, respectively. This may be attributed to higher plant weight observed from 80% AHI treatment than those of deficit irrigation treatments. In other words, when the leaves were desiccated relative difference was bigger. Applying a different watering method for lettuce cultivated in protected areas, influences the plant growth, and so the production obtained. Developing the humidity condition from soil, that means any growing minimal level of watering applying with 10% from IUA caused a growing production. REFERENCES