Jong Myung Choi

INFLUENCE OF ELEVATED PHOSPHORUS LEVELS IN NUTRIENT SOLUTION ON MICRONUTRIENT UPTAKE AND DEFICIENCY SYMPTOM DEVELOPMENT IN STRAWBERRY CULTURED WITH FERTIGATION SYSTEM

The relationship between the total amount of micronutrients absorbed by the above-ground plant tissue and the occurrence of visible micronutrient deficiency symptoms in two strawberry cultivars as influenced by elevated phosphorus (P) levels in fertigation solution was investigated. The plants were cultured with a fertilizer solution containing 0, 0.5, 1, 2, 4, or 6 mM P and tissue nutrient content were determined at 120 days after transplanting. Young leaves of the plants grown with nutrient solution P levels higher than 4 mM and 2 mM, respectively, in ‘Keumhyang’ and ‘Seonhong’, developed interveinal chlorosis. Tissue concentrations (mg·kg−1 dry weight) of metallic micronutrients [iron (Fe), copper (Cu), manganese (Mn), and zinc (Zn)] in both cultivars did not decrease, but the total amount absorbed by the aboveground plant tissue decreased in the treatments in which nutrient deficiencies were observed. These results indicate that total amount of micronutrients is a better indicator of P-induced micronutrient deficiency.

Growth and nutrient uptake responses of ‘Seolhyang’ strawberry to various ratios of ammonium to nitrate nitrogen in nutrient solution culture using inert media

� concentration in the petiole sap, EC and pH of the root substrate were quadratic, with a coefficients of R 2 = 0.99***, 0.98***, and 0.73*.

Visual Symptom and Tissue Nutrient Contents in Dry Matter and Petiole Sap for Diagnostic Criteria of Phosphorus Nutrition for 'Seolhyang' Strawberry Cultivation

Abstract‘Seolhyang’ strawberries (Fragaria ananassa Duch.) were grown in a soilless substrate with fertigation solutions to evaluate the effects of six different P concentrations (0, 0.5, 1, 2, 4, and 6 meq·L−1) on the growth and nutrient contents in dry matter of above-ground tissue and petiole sap. The changes in electrical conductivity (EC) and pH of the root substrate were also investigated. Deficient and excess concentrations of phosphorus, such as 0 and 6 meq·L−1, seriously restricted the plant growth. These two treatments showed the least values in leaf number, plant height, leaf length and width, petiole length, and fresh and dry weights. The solution containing 1 meq·L−1 of phosphorus showed the greatest plant growth compared to the other treatments. The macro-element contents such as P, K, Ca, and Mg showed increased tendencies as P concentrations were elevated but, micro-elements such as Fe and Mn showed decreased tendencies in dry matter of above-ground tissue. When P concentrations were elevated, the pH and EC in the soil solution of root substrate decreased. Considering the crop growth and tissue nutrient contents, the P concentrations should be between 0.5 to 2.0 meq·L−1 and the P contents in the dry matter and petiole sap were 0.23 to 0.62% and 205 to 305 mg·kg−1.

Optimization of substrate formulation and mineral nutrition during the production of vegetable seedling grafts

The use of seedling grafts has been increasingly popular in the production of fruit vegetables in Korea. Superior scion cultivars grafted on seedling rootstocks tolerant to soil-borne diseases often results in higher crop yield and quality. For the production of healthy grafted transplants, seedlings have to be grown under the most favorable cultural conditions. Substrate composition and property as well as mineral nutrition play an important role. Various substrates containing peatmoss, perlite, vermiculite, and coir-dust have been tested for their influence on seedling growth. In the chemical properties of substrates investigated just before grafting and after formation of grafted union, the ECs in 4 substrates rose as the pre-plant fertilizer level was elevated. The ECs in peatmoss containing substrates were lower than those in coir dust containing substrates when all substrates contained equal amount of pre-plant fertilizers. The ECs in substrates containing vermiculite were higher than those in perlite. In all substrates, the elevation of pre-plant fertilizer levels resulted in the increase in NO3−-N and K+ concentrations and decrease in Na+ concentration. The recommended EC levels of substrates for the raising of plug seedlings of bedding plants are applicable to fruit vegetables when the seedlings are grown in peatmoss + perlite (PP) substrate. But those in peatmoss + vermiculite (PV), coir-dust + perlite (CP) and coir-dust + vermiculite (CV) substrates should be altered based on the kinds and rates of substrate components. In case of crops, the water melon rootstock ‘Cham Bak’ (Lagenaria siceraria Standl), showed the stronger salt tolerance than cucumber rootstock ‘Heukjong Hobak’ (Cucurbita ficifolia) indicating that pre-or post-plant fertilizer levels should be varied based on the kinds of crops grown. The peppers grew well in PP and PV substrates rather than CP or CV substrates in before or after grafting. This also implies that the components of substrates should be changed based on the specific crops.

Performance of Seedling Grafts of Tomato as Influenced by Root Substrate Formulations, Fertigation Leaching Fractions, and N Concentrations in Fertilizer Solution

Influence of root substrate formulations, leaching fractions (LF) of fertigation during seedling growth before grafting and fertilizer N concentrations after grafting on growth of tomato grafted seedlings and changes in root substrate chemical properties were investigated. Sphagnum peatmoss + perlite (7:3, v/v, PP) and coir + perlite (7:3, CP) containing pre-plant fertilizers were used as substrates. LF (volume leached/applied) was set as 0, 0.25, 0.50, 0.75 and 0.9 during seedling cultivation. Seedlings of rootstock (J3B Strong) and scion (Sunmyung) were grown in 50- and 105-cell trays, respectively. Plants were fed with 50, 100, or 200 mg·L−1 N using 14-0-14 and 20-10-20 commercial fertilizers alternatingly for seedling stages 2, 3, and 4, respectively. Grafted tomato seedlings planted in 50-cell trays containing PP or CP were callused and rooted inside a humid greenhouse plastic tunnel for 7 days. When grafted tomato seedlings were rooted after acclimation under lower humidity condition, N fertilizers with 4 different concentrations (0, 50, 100, 200 mg·L−1) were applied. During 31 days of culture, highest fresh weight of rootstocks was obtained with 0.75x LF in CP, while PP showing no influence on seedling growth by LF. Electrical conductance (EC) of CP with 0.75x LF was 2.88 dS·m−1. Growth of scion seedlings was largest with 0.25x LF in PP, and EC of this treatment was 0.855 dS·m−1. For 13 days post-grafting, plant growth was better as LF increased for both substrates. When seedlings were grown with 0.90x LF, EC for PP and CP was 0.833 and 2.923 dS·m−1, respectively. Fresh weight of grafted plants grown for 31 days after grafting was the highest with 50 mg·L−1 N for PP and 0 mg·L−1 N for CP. Substrate EC in these treatments were 0.66 and 1.42 dS·m−1, respectively. This study suggests that LF and fertilizer N concentration must be optimized according to substrate formulations for growing high-quality grafted seedlings.

Influence of Incorporation Rates of Sulfur on Reduction of the Bicarbonate Injury in Hydroponic Cultivation of ‘Ssanta’ Strawberry

This research was conducted to determine the influence of incorporation levels of sulfur into a coir dust+pine bark medium (1:1, v/v) on the changes in the bicarbonate (HCO3 ) concentrations and pH of soil solution, crop growth, and nutrient uptake of ‘Ssanta’ strawberry. In the preparing of the mixed medium, sulfur powder was added with the rate of 0 (control), 0.23, 0.45, 0.90, and 1.80 g·L and Hoagland nutrient solution containing 240 mg·L HCO3 was supplied during the crop cultivation. The growth measurements and tissue analysis for the determination of nutrient contents were carried out 140 days after solution application and the soil solution analysis was performed every two weeks. As the level of sulfur was elevated, the overall growth of mother plants became better showing that the growth indexes except chlorophyll contents were the lowest in control treatment but the statistical differences were not found among the three treatments of 0.45 g·L or higher sulfur. The higher the levels of sulfur incorporation, the higher the occurrence of runners and the growth of daughter plants. The length of the runners and the number of daughter plants occurred per mother plants were higher in the treatments of 0.90 and 1.80 g·L than the three treatments of 0, 0.23, and 0.45 g· L, but the statistical differences were not observed between the 0.90 and 1.80 g·L treatments. The rose of pH and HCO3 concentrations in soil solution of root media continued all the cropping period, but those decreased slightly in the treatments of 0.90 g·L or higher. The soil solution concentrations of K and PO4 3in the treatments of 0.90 and 1.80 g·L was lower than those in other treatments and the statistical differences in the Ca and Mg concentrations were not observed among all treatments. The nutrient contents in tissue analyzed in this experiment were the lowest in the control treatments and those increased as incorporation rates of sulfur were elevated. Above results indicated that when ‘Ssanta’ strawberry is grown hydroponically and the root medium is coir dust and the pine bark (5:5, v/v) mix, the sulfur incorporation rate as pre-planting fertilizer has to be higher than 0.9 g·L root medium to reduce the HCO3 injury. Additional key words : daughter plant, inorganic element, mother plant, pH, physiological disorder