Artichoke transplant production: effects of nutrient solution delivery and leaf clipping

Advanced growing systems such as floating systems, widely used to produce leafy vegetables and tobacco transplants, may be a good solution for producing globe artichoke [Cynara cardunculus var. scolymus (L.) Hegi] transplants due to labour saving and rapid plant growth. Leaf clipping is another technique used in tobacco seedling production to reduce height and increase seedling uniformity and quality. Two experiments were carried out under greenhouse conditions. In the first, the effects of two nutrient solution delivery methods (overhead sprinkler system or subirrigation through a floating system) and leaf clipping (with or without) of two seed-propagated artichoke F₁ hybrids, ‘Istar’ and ‘Romolo’, were compared in terms of plant growth, SPAD index and chlorophyll fluorescence. The second experiment aimed to assess the tolerance to water stress of artichoke transplants derived from the four treatments. The effect of leaf clipping was less pronounced than that of nutrient solution delivery method. When averaged over leaf clipping, the shoot dry weight, the root-to-shoot ratio and the maximum quantum use efficiency of PSII were significantly higher by 76.7, 75.0 and 4.0% for ‘Romolo’, and by 39.1, 37.5 and 5.2% for ‘Istar’ with floating raft system compared to the overhead sprinkler system. An opposite trend was recorded for chlorophyll content, since the lowest values of SPAD index were recorded in artichoke transplants grown in the floating system. Artichoke transplants responded in a similar way to water stress after planting irrespective of nursery production system which had limited effect on water stress tolerance after transplanting.