Effects of NaCl and Supplementary Potassium on Gas Exchange,Ionic Content,and Growth of Salt-Stressed Strawberry Plants

Strawberry cultivar ‘Selva’ was grown in a hydroponic culture in a heated greenhouse to study the effects of supplementary potassium (K) added to nutrient solution and applied to the plants grown at high sodium chloride (35 mmol/L) concentration. Treatments were: (1) nutrient solution alone (N); (2) N + sodium chloride (NaCl) (35 mmol/L) (NS); (3) N + NaCl + potassium sulfate (K₂SO₄; 5 mmol/L) (NSK1); (4) N + NaCl + K₂SO₄ (10 mmol/L) (NSK2). Leaf area, biomass production, and gas exchange variables (Pn, E, gs, Ci) negatively affected by salinity. In addition, ionic concentrations (sodium, chlorine, and potassium) increased by salinity treatments. Supplementary potassium had positive effects to ameliorate the harmful effects of NaCl on leaf area. Shoot growing was decreased by potassium (K) application. Ionic concentrations of this cultivar show contradictory results. Although supplementary potassium increased K accumulation, but sodium (Na) and chlorine (Cl) concentrations of plant parts was increased. These results show that potassium can be applied for this cultivar in salinity conditions.     

PRELIMINARY EVALUATION OF COMPOSTED PISTACHIO HULL AND RICE HUSK AS POTTING MEDIUM ON SCINDAPSUS AUREUS VEGETATIVE AND PHYSIOLOGICAL CHARACTERISTICS IN GREENHOUSE CONDITION

Pistachio hull is a horticultural waste product obtained during dehulling process of pistachio nuts. This experiment was carried out to evaluate the effects of pistachio hull and rice husk compost, as culture medium, on vegetative and physiological characteristics of pothos (Scindapsus aureus) plants. Rooted cuttings were used as plant materials and cultured in pots (40 × 30cm) filled with the following media: S₁ = 100% peat (control), S₂ = 100% rice husk, S₃ = 70% rice husk + 30% pistachio hull, S₄ = 50% rice husk + 50% pistachio hull, S₅ = 30% rice husk + 70% pistachio hull and S₆ = 100% pistachio hull. The vegetative parameters were affected by media type, so that no plants survived in 100% pistachio hull. The application of 50% pistachio hull and 50% rice husk (S₄), increased shoot fresh weight, and potassium (K) concentration of shoot and root compared to control. Fresh and dry root weight and phosphorus (P) concentration of shoot was increased with S₂ treatment (100% rice husk).     

Responses of cucumber plant to NH4 and NO3 nutrition: The relative addition rate technique vs. cultivation at constant nitrogen concentration

Different N sources (NO₃⁻, NH₄⁺, or NH₄NO₃) at different relative addition rates (RAR) were supplied to cucumber (Cucumis sativus L.), a species sensitive to NH₄⁺ toxicity. For comparison, cucumber plants were also grown at constant concentrations of 1 and 5 mM NH₄⁺ or 5 mM NO₃⁻. The fresh weight of NH₄⁺-fed plants at RAR 0.15 and RAR 0.25 day⁻¹ was similar to that of NO₃⁻-fed plants, while at RAR 0.35 or RAR 0.45 day⁻¹ growth reduction occurred. When available as a constant concentration, NH₄⁺ decreased plant growth at 5 mM. It is concluded that at low rates of N supply the relative addition rate technique can be used for growing cucumber plants with NH₄⁺ as sole N source without deleterious effects.