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Plant density can affect development and yield of bell pepper (Capsicum annuum L.). Information on the optimum plant density of different types of peppers in the Caspian Sea region is limited. The experiment was arranged in a randomized complete block with three plant densities (30,000, 42,000, and 78,000 plants·ha −1 ) with an in-row spacing of 0.45, 0.30, or 15 m between plants in rows 0.8 m apart and replicated three times. The 42,000 plants·ha −1 density produced suitable vegetative growth, best yield, and did not have any significant negative effects on bell pepper quality.

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The effect of silver thiosulfate (STS) and putrescine was studied on the vase life and quality of cut chrysanthemum in a factorial experiment based on a randomized complete block design. The experimental factors were composed of silver thiosulfate at four levels (0 or control, 0.02, 0.05 and 0.1 mM) and putrescine at three levels (0 or control, 150 and 300 ppm). The results showed that the application of STS at the rates of 0.05 and 0.1 mM improved vase life of cut chrysanthemum. Also, putrescine at the 150 and 300 ppm improved vase life by increasing relative weight and decreasing wilting percentage. The interaction of the two studied factors was insignificant for most traits including wilting percentage and vase life, which may imply that the application of either substance alone suffices to improve postharvest quality and it is not necessary to use them simultaneously in the preservative solution.

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Phalaenopsis amabilis Blume var. grandiflora Bateman is economically important as cut and pot flower. Polyploidy is considered as a valuable tool in improvement and evolution of ornamental plants. Protocorm-like bodies (PLBs) of P. amabilis were cultured on Murashige and Skoog medium containing 0.20 mg L-1 IBA together with 2.00 mg L-1 KIN and 1.00 g L-1 activated charcoal and grown for a period of five months. Fully-developed plantlets from in vitro grown PLBs were immersed in a bubble reactor filled with half-strength Hoagland solution containing the antimitotic agent colchicine (0.05%, 0.10% and 0.15%, w/v) for 72 h with a few drops (1 mL of 0.1%) of octylphenoxypolyethoxyethanol or Nonidet (P-40) as a surfactant. Plantlets were aerated to prevent hypoxia. Colchicine-treated and untreated plantlets were transferred to pots for a period of 60 days. Tetraploidy was successfully induced by 0.15% colchicine. Polyploidy levels were firstly detected using flow cytometry and then confirmed by cytological and morphological observations. The chromosome number was 2n = 2x = 38 in diploids and 2n = 4x = 76 in tetraploid. Incubation of plantlets in liquid medium containing 0.15% colchicine induced the maximum recovered tetraploids with minimum frequency of survival (50%). The tetraploid plants were more compact and exhibited round and thick leaves with darker green color than diploids. Stomata size in tetraploids were larger with less density than diploids. Chloroplast number in guard cells of tetraploids was about two times more than that of control. These results indicate that induction of tetraploids are a reliable and powerful tool for generation of novel phenotypes with ornamental and horticultural value for genetic improvement and breeding. Produced tetraploids in current study have potential in the ornamental/floriculture trade.