Germination of broccoli (Brassica oleracea L. var. italica Plenk) in different seedbed conditions during summer in the Spanish Mediterranean coast

The germination of broccoli (Brassica oleracea L. var. italica Plenk) under high temperatures is problematic this has been pointed out by several authors. Along the Spanish Mediterranean coast seedbeds for autumn crops are established in the summer, when higher temperatures have a negative effect on germination and emergence. The objective of this study was to compare different seedbeds which might improve the percentage of plantlets established during the seedling stage. Seedlings of three broccoli cultivars (Coaster, Gem and Shogun) were placed in four different types of seedbeds: open-air (OA); an 8 m wide tunnel covered with a white shading screen (WS); an 8 m wide tunnel covered with a black shading screen (BS); and 8 m wide tunnel covered with polyethylene (PT). Both germination and emergence of broccoli were better under the black and white shading screens, than in the OA or under PT, and in some cases even better under BS than under WS. Gem also gave better results than Coaster or Shogun in terms of germination and emergence. However, considerable interaction was evident between the different types of seedbeds and cultivars for all the analyzed parameters.