Broccoli [Brassica Oleracea (Plenck) Var. Italica] Plant Growth and Yield as Affected by Colored Plastic Film Mulches

Few studies report on the utilization and benefits of plastic film mulches on broccoli.  The objectives of this study were to determine the effects of colored plastic mulches on broccoli plant growth and yield.  Broccoli (‘Packman’) plants were grown on plastic film mulch and drip irrigation during two fall and one spring seasons.  The treatments consisted of colored plastic film mulches and bare soil.  Root-zone temperature (RZT) was measured at 10 cm below the mulch and the soil surface.  Plastic film mulches affected broccoli plant growth and yield as well as RZT.  The differences in yield among mulches were greater in the spring than in the fall.  Broccoli yield was little affected when mean seasonal RZT was below 21 ºC but increased with increasing mean seasonal RZTs above 21 ºC.  Mean RZTs were highest under dark-colored mulches (blue, black, red, and gray mulches) and lowest under light-colored mulches (silver and white mulches).  Thus, broccoli plant growth and yield responded more favorably to dark colored mulches than to light colored mulches, suggesting that broccoli benefited from increased soil warming.

Keywords: plasticulture; soil temperature; soil degree-days, heat units, temperature stress