The approach to select new growing media, has been focused on selecting materials only from the physical point of view. The objective of this study was to describe the physiological mechanisms involved in I. wallerana growth when cropped on a broad range of growing media created from alternative components. Results showed a close relationship between I. wallerana Downloaded by [New York University] at 12:39 25 May 2015 ACCEPTED MANUSCRIPTACCEPTED MANUSCRIPT 2 growth and fine particle size at the beginning of the experiments. Shoot fresh weight was determined mainly by the root system size. There were small differences in the relative growth rate (RGR) between the control substrate and the thirty alternative substrates tested. The lower RGR values resulted from a decrease in the net assimilation rate and the leaf area ratio. The mechanism involved would be associated with a change in photosynthate partitioning, which favored root growth. A close relationship between growth (as total dry weight) and nitrogen content was found as well.
Pot ornamental plant productivity is related to the environmental growth facilities but negatively affected by the pot root restriction syndrome. Most ferns showed a lower relative growth rate and long production cycles (24 months or more) for which growers use small pots to increase yield per unit area of greenhouse. The aim of this work was to analyze growth changes in response to different pot volume in plants of A. nidus avis spore-propagated under the hypothesis that it would play a role as an abiotic stress which decrease commercial productivity. Our results showed that the use of big pots increased fresh and dry weight and frond area (the main aesthetic trait). When growth parameters were performed, a higher the frond appearance rate (RLA), the frond area expansion (RLAE) and the frond thickness (SLA) were found in 1500 cm3 pot as well as the relative growth rate (RGR) and the net assimilation rate. The use of biggest pot for fern cropping stimulated biomass accumulation through a higher capacity to initiate and expand fronds, to increase photosynthetic rates and change photo assimilate partitioning which favor shoots. From the grower´s point of view, our results suggested that higher yields of A. nidus avis fern would be reached decreasing root restriction, that is, to use the biggest pot volume from the early transplant from plug trays.
Ferns are ornamental plants with a low relative growth rate and long production cycles, which are grown at small pot volumes to optimize the commercial space for sale. However, the root restriction effects under this plant management can limit biomass accumulation and frond area. Since an exogenous spray with cytokinin (6-benzyl aminopurine (BAP)) has been suggested as a tool to override the root restriction in plants grown in pots, this study aimed to evaluate the effect of different BAP doses (5, 50, 100 or 200 mg L-1) once (7 days after transplant), twice (7 and 30 days after transplant) or three times (7, 30, and 60 days after transplant), on plant growth and frond area development in spore-propagated Asplenium nidus fern plants grown in pots. Both increasing the BAP doses and number of applications led to an unusual response: an excessive decrease in the frond plastochron and a significant increase in the frond number initiated at the apical shoot meristem. This large frond number was not sustained due to the low net photosynthetic rate of the younger fronds and significantly limited outward appearance.
Abstract:The aims of this work were to study the effect of two different plastic containers on asparagus growth and the effect of early applied 6-benzilaminepurine (BAP) on crown growth during the first two years after seed germination. Although there was not found a root restriction effect with the use of plastic containers, there were significant differences between plants grown in plastic seedbed or single pots which suggesting an unusual and unexpected asparagus autotoxicity. The results showed that crown fresh weight, total dry weight, relative growth ratio (RGR root ), root:shoot ratio and photosynthetic shoot number increased in BAP-sprayed plants over the controls without treatment as a result of a change in photosynthate partitioning towards the root system. The BAP sprays seem to be a greater effect under conditions with favor autotoxicity such as the seedbed than in single pot crown-grown.
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