THE INFLUENCE OF DIFFERENT SUBSTRATE COMPOSITION ON GROWTH PARAMETERS AND DRY MASS PARTITIONING OF CUCUMBER (CUCUMIS SATIVUM L.) SEEDLINGS

Abstract

The influences of substrate composition on growth parameters and dry mass portioning of cucumber (Cucumis sativum L.) seedlings were estimated in an experiment conducted in a plastic greenhouse. Graded seeds of cv. Ekron F1, were individually seeded in foam trays filled with different substrates, namely peat compost (Klassmann product), vermin compost (locally produced) and a mixture (50 % to 50%) of peat compost and vermin compost. Plants were equally irrigated, but no additional nutrient elements were supplied during the experiment time. Roots, stems and leaf dry matter were weighted and stem length and plant leaf area was successfully measured after the first and the second true leafs were appeared. Based on that data, the relative growth rates (RGR) and its components; net assimilation rate (NAR) and leaf area ratio (LAR) were computed. The relative stem elongation rate (RSER), the relative leaf expansion rate (RLER), root to whole plant dry weight ratio (RWR), root to shoot dry weight ratio (RSR), and the respective fractions of roots, stems and leaf dry mass against total plant weight (RMF, SMF, LMF) were also calculated for each experimental plot. A significantly higher relative growth rate (RGR) was found for young seedlings grown in vermin compost compared to commercial peat compost. Though there was a difference on net assimilation rate (the physiological component of RGR), the increased growth rate was mostly due to differences found for leaf assimilation ratio (the morphological component of RGR). Higher dry matter per plant, higher relative stem elongation rate and higher relative leaf expansion rate were found for vermin compost, but no effect was found regarding dry mass partitioning of young cucumber seedlings.