هیدروپونیک

Calcium is one of the most important minerals that plays important role in resistance to plant pests and diseases, One of the accumulation sites of this element is the plant cell wall. The presence of calcium pectate in the cell wall is essential for plant survival. Lack of calcium in pistachio fruit causes the Endocarp Lesion in early May during the millet stage and fruit is growing. Calcium spraying is one of the strategies to eliminate the Endocarp Lesion that has become prevalent in recent years. various calcium-containing compounds are used, including various chelates and calcium fertilizers. The seeds of two cultivars of pistachio Badami Zarand and Qazvini were planted in hydroponic culture medium. After one month, complete nutrient solution (HF) with the percentage of elements and the same solution but without calcium (H) were added to the pots. The nutrient solutions were changed monthly. Calcium-containing solutions including calcium chelate, calcium nitrate and calcium acetate were prepared at a concentration of 2 per thousand and all pots were sprayed in 4 varieties at intervals of 5 days. After 4 months, seedling height, crown diameter and concentrations of calcium, magnesium and phosphorus in the plant were measured. The results showed that foliar application of different calcium-containing compounds had no significant effect on calcium concentration of pistachio seedlings. However, the use of calcium in the nutrient solution of the culture medium and also the type of cultivar had a significant effect on the calcium concentration in the plant. Also, foliar application of calcium acetate caused a significant increase in phosphorus concentration in the plant. It seems that foliar application of calcium acetate probably increased phosphorus uptake due to its acidic nature.

Nowadays, the cultivation of vegetables in greenhouses using soilless beds has become a widely adopted practice for vegetable production worldwide. The inclusion of new greenhouse crops like melons offers the potential to supply consumers with fresh and high-quality produce. Greenhouse melon cultivation is a relatively new practice in Iran, and there is a scarcity of published information regarding its various aspects of production in a greenhouse setting. One crucial factor that significantly influences the quality and quantity of greenhouse crops, such as melons, when employing soilless cultivation techniques, is the selection of appropriate nutrient solutions. Therefore, the current study was conducted to investigate the influence of different nutrient solutions on vegetative growth, seed and fruit characteristics, and biochemical status of three melon cultivars (Ahlam, Polinica, Curie) under greenhouse condition.           

The present study was conducted at the Horticultural Sciences Department of Shahid Chamran University of Ahvaz in southwestern Iran during the 2017-2018. A factorial experiment based on randomized complete blocks design with three replications, was carried out to assess the impact of three nutrient solution treatments (Pars, Shizuoka, Hachmath) and three different cultivars (Ahlam, Polinica, Curie) on key characteristics of greenhouse melon. The melon plants of the three cultivars were cultivated in pots containing 8 L of a growth medium consisting of a 4:1 ratio of cocopeat to perlite. At the end of experiment, four characteristic groups including vegetative growth parameters (dry weight of leaf, root, stem and plant and the ratio of leaf dry weight to root dry weight), seed characteristics (seed dry weight and hundred seeds weight), physical parameters of fruit (length, diameter, weight, wide of seed cavity and flesh thickness) and biochemical traits (ascorbic acid content, carotenoid content, taste index, total soluble solid content and titratable acidity) were measured.

The findings demonstrated that in the Hochmuth and Pars nutrient solutions, the Ahlam cultivar exhibited the highest total dry weight (63.66 g and 37.65 g, respectively). However, the Polinica cultivar showed the highest total dry weight in the Pars nutrient solution. The Hochmuth nutrient solution resulted in the highest leaf dry weight for the Ahlam cultivar (43.77 g). The Ahlam cultivar also displayed the highest fruit weight (1584 g and 1510 g, respectively), dry weight of hundred seeds (4.04 g and 3.56 g, respectively), seed dry weight per fruit (11.56 g and 10.75 g), weight of seed cavity contents (104.10 g and 114 g, respectively), fruit diameter (13.51 cm and 13.58 cm, respectively), and fruit lengths (17.58 cm and 18.28 cm, respectively). The weight of seed cavity content was influenced by both the cultivar and the nutrient solution. The Ahlam cultivar, when fed with the Pars nutrient solution, exhibited the highest total titratable acidity (0.07 %) and seed cavity thickness (6.38 cm). Regarding the Polinica cultivar, the Pars nutrient solution resulted in the highest total soluble solids (11.98 %B) and taste index (337.3), while the Hochmuth nutrient solution led to the highest ascorbic acid content (1.05 mg g-1 FW). The nutrient solution treatments did not have a significant effect on carotenoid content of the melon cultivars. Different amounts of elements in different nutrient solutions cause different growth behaviors of plants. For instance, the melon plants fed with Pars nutrient solution showed higher values of growth parameters comparing to the other plants, and it could be related to high N content of this solution. The similar results have been reported on the other crops such as cucumber and tomato.

The outcomes of the current study, which investigated variations in vegetative growth, yield, and quantitative and qualitative traits of melon cultivars under different nutrient solutions, indicated that the genetic traits of the cultivar, vegetative growth, and quality attributes of melon fruit were influenced in the presence of cocopeat and perlite media. The findings suggest that prior to selecting a melon cultivar for greenhouse cultivation, it is crucial to assess the impact of various nutrients on both vegetative growth and the qualitative characteristics of the fruits. Conducting such experiments can enhance the efficiency of nutrient utilization in greenhouse melon production.

Lettuce (Lactuca sativa L.) is one of the most important leafy vegetable. Due to importance and high demand the greenhouse and hydroponically growing of lettuce is increasing. One of the key points in effectiveness of hydroponic production is the formulation of suitable nutrient solution. Nitrogen as an essential element could be provided by two form in nutrient solution, ammonium and nitrate. Although both form provide the nitrogen for plants but they can affect the growth and physiological aspects differentiatly. In other side open systems of hydroponic in addition to to high cost for nutrient solution preparation can cause soil and water pollution, so its need to use hydroponic systems that decrease the amount of nutrient solution consumation. In this study we assessed the effect of three different NH4+:NO3- ratio in nutrient solution in an easy and very low cost closed hydroponic system so called Kratky method on lettuce production.

The experiment was conducted in hydroponic greenhouse as a factorial based on completely randomized design. Three nutrient solutions with the same level of total nitrogen but with different ammonium to nitrate ratio (0.5:8, 1:8 and 2:8) were used for growing the three lettuce cultivars (Local Romain, French red and Salinas) in closed hydroponic system without the exchange of nutrient solution during the growing cycle and just water were added to substition the of the consumed solution. The seeds of lettuce cultivars at first were planted in cell try that were filled with coco peat-perlite with 1:1 ratio and after emergence and until reaching to suitable size for transplating seedling were fertigated with hoglnd nutrient solution. Two lettuce seedlings were transplanted via the small plastic small baskets and styrofom plate in pots with seven liters volum until the end of growing period. The characters like leaf and root fresh and dry weight, chlorophyll, carotenoid and anthocyanin content were assessed.

The results indicate that the ammonium:nitrate ratio had significant effect on the lettuce leaf and roots fresh and dry weight, chlorophyll index and anthocyanin contents. The cultivars had significantly difference effects on leaf and roots fresh and dry weight, collorophyl index, carotenoid and anthocyanin content. But the interaction between the ammonium:nitrate ratio and lettuce cultivars were not significant on the investigated characters. Between the cultivars Salinas and locally Romaine respectively had the highest and lowest yield. The highest and lowest root fresh and dry weights also were obtained from the 2:8 and 0.5:8 ammonium to nitrate ratios respectively while the 0.5:8 and 1:8 ammonium to nitrate ratio were not the significantly different from each other on the leaf fresh wight. The same rule also was for the leaf dry weight. The Salinas and French red had the highest dry weight and the localy romain significantly leaf lowest dry weight. On the roots fresh and dry weight characters there was significantly difference between the cultivars that was close to the results on leaf fresh and dry weight. So that Salinas withought the significantly difference with the French red had the highest root fresh weight and lowest root fresh weight belongs to locally romain. Result showed that lettuce being a vegetative crop satisfied by increasing the ammonium:nitrate ratio in nutrient solution. This is close to the results that previously has been reported by some authors.

The highest fresh and dry weights of lettuce were obtained by the solution with the 2:8 ammoniums:nitrate ratio, which indicate the superiority of the lettuce simultaneously feeding with nitrate and ammonium. In addition to quatitative characteristic like the yield the yield, simoultaneously feeding with ammonium and nitrate affected the qualitative characteristics like the anthocyanin and cartenoeid contents. Also providing the some parts of Nitrogen needs of plant as ammonium can reduce the nitrate accumulation. All of three nutrient solution with different ammonium to nitrate ratio but with the same level of total nitrogene and without any need to aeration also without the change of nutrient solution and only by substitution of consumed water were able to feed the lettuce plants without any visible disorders. This kind of hydroponic due to the drastic decrease of production costs would be suitable method specially for small scale hydroponic vegtable production greenhouse.

Most growers do not pay attention to the issue of proper nutrition, including the proper ratio of elements in the nutrient solution and changing the concentration of each element and their ratio at different stages growth. Lack of available information in this regard, in the present study, it has been decided to evaluate the effect of different ratios of nitrogen and potassium on the quantitative and qualitative characteristics of tomato fruit under hydroponic conditions. The balance of nutrients in the culture medium is one of the factors affecting the yield and quality of crops and horticulture. The present study was conducted to investigate the effects of different ratios of nitrogen and potassium on the quantitative and qualitative characteristics of Hirad tomato fruit in hydroponic conditions.

Treatments include concentrations of nitrogen and potassium in the vegetative and reproductive period including 1) nitrogen and potassium at concentrations of 130 and 250 ppm in the vegetative stage and 160 and 350 ppm in the reproductive stage; 2) nitrogen and potassium at concentrations of 140 and 260 ppm in the vegetative stage and 170 and 360 ppm in the reproductive stage, respectively; 3) nitrogen and potassium at concentrations of 150 and 270 ppm in the vegetative stage and 180 and 370 ppm in the reproductive stage, respectively; and 4) nitrogen and potassium were at concentrations of 160 and 280 ppm in the vegetative stage and 190 and 380 ppm in the reproductive stage, respectively.

The results showed that the nutrition of tomato plant with different ratios of nitrogen and potassium affects different characteristics of the plant such as quantitative and qualitative indicators. The highest stem diameter value was obtained in the vegetative and reproductive stages in treatment 3. Treatment 2 showed the highest yield of single plant, total acid and fruit lycopene, and in treatment 4, the highest amount of fruit chlorophyll and soluble solids was observed.

Also, the highest ascorbic acid content was obtained in treatment 1.In general, in order to achieve maximum yield and improve the quality of tomato fruit, it is recommended to use more potassium and less nitrogen.