Ahmet Turhan

Influence of rootstocks on yield and fruit characteristics and quality of watermelon

The objective of this study was to examine the effects of grafting and kinds of rootstocks on yield that are economically feasible for the watermelon producer. Fruit characteristics and quality attributes of grafted plants in open field conditions were also analyzed. The tongue approach grafting method was adopted. Three Watermelon cultivars of ‘Crimson Tide’, ‘Dumara’, and ‘Farao’ were used as the scion. Three hybrid squashes of ‘Dynamo’, ‘RS-841’, and ‘Shintosa’ were used as rootstocks. Results showed that some fruit quality indicators such as dry matter, total soluble solids, total sugar and titratable acid contents were lower in grafted plants while lycopene contents remained unchanged. The pH was slightly altered by grafting. Use of rootstock did not show advantages at comparable fruit quality indicators. Results also showed that fruit shape index, rind thickness, fruit weight, total yield and marketable yield were significantly influenced by grafting. Use of rootstocks significantly increased previously mentioned values which is related with yield, as compared to the non-grafted plant. Analyses proved the use of rootstocks as economically feasible and an advantageous alternative in watermelon production.

Optimizing levels of water and nitrogen applied through drip irrigation for yield, quality, and water productivity of processing tomato (Lycopersicon esculentum Mill.)

The main goal of this study was to evaluate the effects of different levels of irrigation water and nitrogen on yield, quality, and water productivity of processing tomato grown in clay-loam soil. Three water levels of pan evaporation (Epan) replenishment applied via drip irrigation (1.00 × Epan, 0.75 × Epan, and 0.50 × Epan) and four N application rates with fertigation (0, 60, 120, and 180 kg N·ha−1) were tested in the sub-humid climate conditions of Turkey during the 2010 and 2011 growing seasons. The highest marketable yields were observed with full irrigation (1.00 × Epan) for each season. Decreasing irrigation rate generally improved dry matter, total soluble solids, total sugars, titratable acidity, lycopene and total carotene, and decreased fruit NO3-N content and fruit total protein content slightly. The highest water productivity was obtained with a moderate soil water deficit (0.75 × Epan). The 180 kg N·ha−1 fertilization rate produced the highest values for marketable yield, fruit size, total soluble solids yield, NO3-N, and total protein content. Increasing N rate also increased the values of fruit total sugars and titratable acidity. Increasing both irrigation and N levels increased the NO3-N and protein contents. The higher lycopene and total carotene values were obtained in the treatments of 60 and 120 kg N·ha−1. Increasing N supply improved the water productivity with the 3 irrigation application ratios. Considering the quantity and quality for the processing and water productivity, the 0.75 × Epan irrigation regime and a 120 or 180 kg·ha−1 nitrogen supply can considered optimal.

Yield and economic return of drip-irrigated vegetable production in Turkey

Abstract Field experiments were conducted for 2 years (2004 and 2005) on sandy loam soil in south Marmara region of Turkey to study the effect of five levels of pan evaporation replenishment (20%, 40%, 60%, 80%, and 100%) on marketable yield, irrigation water productivity (IWP), and economic return of tomato (Lycopersicon esculentum), pepper (Capsicum annuum), green bean (Phaseolus vulgaris), and eggplant (Solanum melongena) under a drip irrigation method. The highest mean marketable yield (2 years) of tomato (87.5 t ha−1), pepper (59.2 t ha−1), green bean (7.6 t ha−1), and eggplant (46.5 t ha−1) was recorded at 100%, 100%, 80%, 100%, and 80% of pan evaporation replenishment, respectively. The IWP of tomato (23.6 kg m−3), pepper (16.5 kg m−3), green bean (2.6 kg m−3), and eggplant (13.6 kg m−3) was the maximum at 80%, 80%, 40%, and 80% of pan evaporation replenishment, respectively. The results revealed that a further increase in irrigation amount resulting from 100% of pan evaporation replenishment did not increase the marketable yield of crops but reduced the IWP significantly. The net return increased with the increase in pan evaporation replenishment. The results revealed that the pepper is the most profitable crop, followed by tomato, eggplant, and green bean.

Effect of different concentrations of diluted seawater on yield and quality of lettuce

This study was carried out to investigate the effects of irrigating lettuce (Lactuca sativa L. cv. Funly) with different concentrations of diluted seawater (0%, 2.5%, 5%, 10%, 15%, 20%) on the fresh yield, marketable yield and quality (DM, total soluble solids, titratable acidity, total sugar, vitamin C, NO3-N, protein, and total oxalate content). The experiments were conducted in a greenhouse in the autumn of 2012. The fresh yield, marketable yield, and DM of lettuce irrigated with 2.5% and 5% seawater were similar to those of control, but these parameters decreased in response to 10% seawater, and the lowest values were obtained in response to 20% seawater. The 2.5% seawater treatment had no effect on the vitamin C and NO3-N content, but both significantly decreased when lettuce was irrigated with seawater concentrations higher than 2.5%. Total soluble solids, total sugar, and protein content significantly increased in response to low salinity (2.5% and 5%) but decreased in response to increasing seawater stress. The titratable acidity values remained unchanged under the various saline conditions. Irrigation with diluted seawater did not affect the total oxalate content up to a concentration of 5%, but increasing the concentration of seawater above 5% increased oxalate content. The results of this study demonstrated that low concentrations of seawater are suitable for lettuce production and lettuce can be grown successfully using diluted seawater at concentrations of 2.5% and 5%.

Alleviation of deleterious effects of salt stress by applications of supplementary potassium–calcium on spinach

Abstract The aim of the present study is to investigate the effects of salinity and the influence of supplemental K+ and Ca2+ on the alleviation of the deleterious effects of salinity stress in spinach plants. Spinach cultivars used were Green Gold, Larissa, Mikado, Ohio and Matador. In addition to four NaCl levels of 50, 100, 150 and 200 mM, the treatments were repeated with 10 mM K and 10 mM Ca at each NaCl level. The results revealed that Na+ and Cl− concentrations were significantly increased and the K+, Ca2+ and NO3 − concentrations were decreased with increasing NaCl concentrations in the growth medium. Being very important to the physiology and biochemistry of plants decreases in K+, Ca2+ and NO3 − reduced both growth and the yield. The additions of K+ and Ca2+ reduced the Na+ and Cl− concentrations in the plant tissues, increased the K+, Ca2+ and NO3 − concentrations, resulting in an improvement in the marketable yield of the spinach plants. Even though the effects of supplemental K+ and Ca2+ were similar in some plants at different salt concentrations, the effect of additional Ca2+ alone was higher overall. Thus, the results of this study confirmed the principal effects of K+ and Ca2+ supplies in reducing the detrimental effects of salinity.

Response of red pepper to deficit irrigation and nitrogen fertigation

ABSTRACT The main objective of this investigation was to evaluate the response of red pepper grown in a subhumid climate to different irrigation and nitrogen levels. Open-field trials were conducted in the Marmara Region, Turkey. Plants were subjected to three water levels [full irrigation (FI) = 100% crop evapotranspiration (ETc) and two deficit irrigations (DIs)= 66 and 33% ETc restoration] and four levels of N (0, 80, 160, and 240 kg N ha−1) during the 2012, 2013, and 2014 growing seasons. A split-plot experimental design was used. The highest values of biomass and marketable yield (MY) were observed under FI. DI significantly increased the fruit soluble solids content. The biomass yield, MY, and fruit weight significantly improved with increasing nitrogen levels. The 240 kg N ha−1 treatment under FI provided the maximum net income. Increasing N supply under DI conditions enhanced the water-use efficiency based on both biomass yield and MY. These results indicate that with respect to the yield, the net income, and the water productivity of red pepper, the FI with a nitrogen supply of 160–240 kg ha−1 is recommended for drip irrigated and N-fertigated red pepper under subhumid climate conditions.

Economic Return versus Crop Water Productivity of Watermelon under Full and Deficit Irrigation Conditions

Field research was carried out in a sub humid climate at the Uludag University, Bursa, Turkey. Using the yield data obtained from the field research for 2011 and 2012, a partial economic analysis was conducted for watermelon (Citrullus vulgaris, var. Crimson Sweet) at four drip irrigation treatments of full irrigation [FI, 100% evapotranspiration (ETc)] and deficit irrigation (DI) [75% FI, 50% FI and 25% FI] and then compared to both physical and economic water use efficiency (WUE). Total costs and net incomes differed among irrigation strategies. Marketable yield (MY) and net income to land decreased with decreases in the amount of irrigation. The highest MY and net income to land were obtained with the full irrigation treatment. The results showed that full irrigation is recommended under non-water-limiting environments for higher yield and net income. The highest net income to water, physical WUE and economic WUE values were resulted from the 75% FI. With consideration to net income and water use efficiency, deficit irrigation management strategy of 75% FI under water-limiting conditions can be preferable, because it achieved irrigation water savings of 25%, an increase of 9% in crop water use efficiency and an acceptable net income with a yield loss of only approximately 8% compared with full irrigation.