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University of KwaZulu-Natal (1982)

Soilless cultivation of cucumbers and tomatoes under protection in Natal.

Smith, Irwin Elcoate.

Titre : Soilless cultivation of cucumbers and tomatoes under protection in Natal.

Auteur : Smith, Irwin Elcoate.

Université de soutenance : University of KwaZulu-Natal

Grade : Doctor of Philosophy 1982

Résumé partiel
Research into aspects of tomato and cucumber production under protection in Natal has shown that good crops can be obtained using soilless media and nutriculture methods. Tomato and cucumber seedlings were grown in polystyrene seedling trays with cone shaped cavities. A standard tray (675 x 343 mm) with 72 cavities resulted in better seedling growth than 128 and 228 cavities per tray. Seedling growth was reduced in the smallest cavities, but was acceptable in the 128 trays considering cost of media and transport, provided the seedlings were not left too long in the trays. Seedlings grown in these trays in local peat adjusted to pH 6,3 grew better than in local peat:vermiculite, or vermiculite only adjusted to the same pH. In comparing different comme rcially formulated media with local peat, better seedlings were obtained in Finnish and Canadian peat which was pH stabilised and pre-enri ched. Subsequently, pine bark milled through a 6 n screen and with added nutrients gave equ ally good results as the imported peats. Conmlercially available compl ete nutri ent solutions watered onto seedlings in these media were equally good provided that they were adjusted to contain equal levels of N, P and K. fIt label recommendati ons ® J\quapon was better than ® Chemicult and ® Speedling. Best results were obtained where a nutrient solution containing 184 ppm N, 27 ppm P and 130 ppm K was used at every watering. Applying the sc ;ll1e total amount of nutrient, but only on alternate days with water only i n between, or applying solids once a week was not as good as the best treatment. For grm’ling tomatoes and cucumbers optimum temperature recommendations worldwide are 18-23/15-18 °c (day/night) and 21/19 °c respectively. In plastic tunnels in Natal temperatures ranging from 1 to 30 °C, .alld from 18-40 °c were measured in winter and summe r respectively. Associated rooting medium temperatures in pots varied from a fil Hllmum of 6 °c to a maximwn of 15 DC in winter, rising to 24 °c on the ’ I m northern side of the E-W orientuted tunnel. In summer these temfJ( ; f’


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