Mohammad saeid Jafari; Hamideh Noory; Abdol-Majid Liaghat; Hamed Ebrahimian
Abstract
Lettuce is one of the most important leafy vegetables used primarily for fresh and salad applications. The purpose of this study was to investigate the effect of different levels of water and nitrogen on lettuce yield and find the best irrigation and nitrogen fertilizer practices for producing this crop ...
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Lettuce is one of the most important leafy vegetables used primarily for fresh and salad applications. The purpose of this study was to investigate the effect of different levels of water and nitrogen on lettuce yield and find the best irrigation and nitrogen fertilizer practices for producing this crop in drip irrigation. Iceberg variety of lettuce was planted in 2018 with three irrigation treatments (I1, I2 and I3 to provide 100%, 80%, and 60% of crop evapotranspiration, ETa, respectively) and four nitrogen treatments (N1, N2, N3, and N4 to provide 105, 70, 35 and zero kg of nitrogen per hectare in total, respectively). In 2019, two irrigation treatments (I1 and I3) and two nitrogen treatments (N1 and N4) were used. The experiment had a randomized complete block design with three replications. The results indicated that the effect of irrigation and nitrogen treatments and their interactions on the marketable yield of lettuce; but the dry matter produced was only affected by irrigation and nitrogen treatments. Maximum marketable yield and dry matter production were 66.1 ton.ha-1 and 2728.2 kg.ha-1 for full irrigation treatment with 105 kg.ha-1 nitrogen (I1N1) treatment, respectively. The minimum marketable yield and dry matter were 37.5 ton.ha-1 and 1929.6 kg.ha-1 for 60% ETa treatment with 35 kg.ha-1 nitrogen (I3N3) treatment, respectively. The maximum and minimum irrigation water productivities for marketable yield were 21.63 and 15.38 kg.m-3 for I2N1 and I3N3 treatments, respectively. The linear and nonlinear production functions of yield-water and yield-nitrogen were obtained for lettuce variety Iceberg, which can be used in similar environmental conditions in research and practical applications.
morteza khoshsima; Hamideh Noori
Abstract
In order to study the effect of irrigation water salinity on some chemical parameters and distribution of salt in soil profiles under drip irrigation system (T-tape), a factorial experiment with Randomized Complete Block Design (RCBD) was carried out in the research farm of the department of irrigation ...
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In order to study the effect of irrigation water salinity on some chemical parameters and distribution of salt in soil profiles under drip irrigation system (T-tape), a factorial experiment with Randomized Complete Block Design (RCBD) was carried out in the research farm of the department of irrigation and reclamation engineering, University of Tehran, Karaj, Iran, during June to October 2017. The treatments consisted of three maize hybrids SC 260, SC 400, and SC 704 (V1, V2 and V3) and three levels of irrigation water salinity of 0.7, 3, and 5 dS/m (S1, S2 and S3). To study the salinity profile in the soil during the plant growth period, ECe, pH, Na+, K+ and (Ca2++Mg2+) cations were determined in 0-20, 20-40 and 40-60 cm soil layers and at a distance of 10 and 20 cm from irrigation lines. The result of variance and comparison of the mean measured properties at 0-20 and 20-40 cm soil layers, (ECe and Na+) showed that there was a significant difference between soil salinity (ECe) and sodium (Na+) under different levels of water salinity and depth of soil. The soil salinity and sodium content were directly correlated with irrigation water salinity and growth period of maize hybrids, and had an inverse relationship with soil depth. Indeed, the highest amount of soil salinity (13.4 dS/m) and soil sodium (95.6 meq/L) in the 0-20 cm layer was in V3S3 and the lowest (2.4 dS/m and 5 meq/L) was observed in the 20-40 cm layer of V2S1. Also, regardless of salinity treatments, there was no significant difference between the three hybrids and the salt absorption potential was the same for all tree hybrids. In saline irrigation treatments (i.e. 3 and 5 dS/m), the wetting front moved less away from the irrigation line, and most salt accumulation was observed at a distance of 10 cm from irrigation line and soil surface due to plant consumption and evapotranspiration. According to the results of this study, in the conditions of using saline water for irrigation of crops using a drip irrigation system, at the end of the growing season or in the next winter, leaching is needed to remove salts in the soil surface layer from the root zone of the next crop.