Amanollah Soleimani

Optimizing light and nutrient supply has a key role in seedling quality and yield of cucumber seedlings. The combined effects of light quality {blue (B), white [W; 41% B, 39% intermediate, and 20% red (R)], RB [red (80%) and blue (20%)], and red (R)} and EC value of the nutrient solution (1, 1.7, and 3 ds m-1) were evaluated on the growth and physio-logical responses of cucumber seedlings. The measurements were aimed at the growth rate, biomass distribution, water status, seedling quality, yield, and concentration of photosynthetic pigments, protein, proline, potassium, and phosphorous. The results showed that the effects of light quality on cucumber seedlings depended on the EC values of the nutrient solution. The RB treatment at EC 1.7 of the irrigation water had the highest value of seedling quality parameters and the maximum amount of osmolytes, elements, and pigments, showing adequate water performance. Moreover, in contrast to the conventional seedling production, yield and biomass production increased by 70% and 92%, respectively, in the transplanting phase. This probably resulted from a more efficient elemental uptake, higher biomass distribution, and low vegetative growth in the seedling production phase. These results can contribute to seedling production of vegetables as an efficient protocol for yield productivity. In sum, our findings showed that determining the ideal light spectrum for seedling growth should be considered together with the EC of the nutrient solution.