| The trial was carried out at Chongqing, the southwest region of China by cultivation of tree new cultivars of firm-flesh strawberry (Fragaria ananassa: F chiloensis X F virginiana) introduced from France (Darselect: Parker X Elsanta) and Spain (Tudla: Parker X Chandler and Cartuno) respectively. The biological and agronomical features such as ripening precocity, productivity, resistance to diseases and fruit quality etc. were comparatively observed. The biochemical and physiological characters as well as the biomass and metabolic reactions of strawberry plants cultivated in pot were largely studied under artificial water stress conditions. The results showed that Tudla is the most adapted cultivar in the region in terms of vigor, fruit weight, productivity and trans-storage. Its hollow core and lower content in soluble solid substances are however considered as disadvantage for Chinese consumers. Anyway, it will be full of perspective in the South of China in condition of augmentation of fruit sugar percentage by cultural practices. As for Cartuno, it has also a vigorous growth with a smaller fruit caliber than Tudla. But it showed lower yield, worse trans-storage and more sensible to powdery mildew (Shaerolheca humuli or Oidium fragariae) and gray mold rot (Botrytis cinerea) than the other two cultivars. As contrast, Darselect presented a best quality with regard to sugar content in fruit, particular strong flavor and good aspect and trans-storage as well as applausive organoleptical taste and predilection demonstrated by Chinese people. Nevertheless, its lower productivity with smaller fruit than that in the origin location (cx. France and North region of China) could be improved through judicious planting dates and culture modes. It is still considered as a good cultivar for the south region. According to the variation of vegetative and reproductive manners of the cultivars, we should take different culture methods, for example, as in Tudla and Cartuno, fertilizing more organic material with more than 75 tons/ha and planting with a density between 45,000 to 60,000 plants/ha; as in Darselect, with a denser planting than usual (75,000 to 90,000/ha) in association with flower and/or fruit thinning during blossom period. Tudla and Cartuno had a strong potential of runner propagation, so that the planting spacing for a mother plant should be more 0.5 m2 in stock nursery. However the excellent features of Darselect could not completely exhibit as in the Northern, therefore it is worthwhile studying profoundly these problems. Under the artificial water stress, the strawberry grown in pot showed an increase of water saturation deficit in the leaves at the expense of foliar water content (WC) and its relative water content (RWC) principally due to diminution of the free water (WF). Darselect was characterized by a strong sotomatal regulation and a weak reduction of RWC and WF. Thus it had a lower ratio of water lose or stronger water holding capacity as well as resistance to drought than Tudla and even Cartuno. The water stress induced also a significant increase in cell solutes such as proline (Pro), soluble sugars (SS), K etc, which in return reduced the osmotic potential in cytoplasm and correlated negatively with the soil water content (SWC). Contrarily, the soluble protein has shown an insignificant osmoregulation. As for strawberry plant, Darselect represe... |
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