Colored Shade Cloth Affects the Growth of Basil, Cilantro, and Parsley

A preliminary experiment evaluated the effect of plant growth regulators (PGRs) or mechanical stimulation (brushing) on branching of sweet basil (Ocimum basilicum L.), cilantro (Coriandrum sativium L.), and parsley (Petroselinum crispum (Mill.) Nyman ex A.W. Hill). Dikegulac sodium increased branching in sweet basil up to 400 ppm and thereafter branching decreased compared to control plants. Ethephon increased branching in sweet basil as rate increased up to 500 mg/L compared to control plants. Mechanical stimulation resulted in a significant decrease in plant height, plant width, number of branches, and number of leaders for all species compared to control plants. Benzyladenine and metaconazole had no effect on these species. In the main experiment the effect of colored shade cloth and PGRs or brushing were assessed on sweet basil, Thai basil (Ocimum basilicum "Siam Queen" L.), Genovese basil (Ocimum basilicum "Genovese" L.), cilantro, and parsley. All crops were grown under conventional black, blue ChromatiNet®, or red ChromatiNet® shade cloth. Subplot treatments included: dikegulac sodium at 400 ppm; benzyladenine at 300 ppm; ethephon at 350 ppm; brushing at 10 strokes applied twice daily. We assessed volatile compunds on all crops and conducted a sensory panel on sweet basil. Red shade cloth increased the number of branches and shoot fresh weight in sweet basil, Thai basil, and Genovese basil. Number of leaf stalks and shoot fresh weight also increased in cilantro plants grown under red shade cloth. Red shade cloth increased fresh weight of parsley plants. Sensory panel results showed a preference for the appearance of sweet basil grown under red shade cloth. Red shade cloth can be used to grow sweet basil, Thai basil, Genovese basil, cilantro, and parsley plants that have more branches and higher fresh weights.