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Effect of nitrogen on photosynthetic parameters and yield of gerbera crop (gerbera jamesonii bolus ex hook. F.)

Abstract:

There is a current interest in understanding the physiological aspects involved in gaining high crop yields, and their relationship with biomass production and substrate nutrient availability. This knowledge will allow the recommendation of accurate nutrient doses, avoiding problems associated to imbalances in both the soil and the environment. This study evaluated some physiological responses of Gerbera jamesonii (cultivar Cirilo®) under the effect of four nitrogen fertilization treatments (75, 56, 94 and 112.5 mgN plant-1day-1). We also sought to relate these possible responses with growth characteristics. Plants were arranged in a completely randomized design with 3 replications to which gas exchange (CO2assimilation, transpiration, and stomatal conductance), leaf water potential and quantum yield of photosystem II were measured. These variables were related to vegetative growth (total leaf area) and quality and flower production variables (floral stem length and diameter, flower head diameter and number of monthly flowers). The results show that increasing substrate N doses resulted in an increase in CO2 assimilation for this cultivar (from 9.2 to 12.1 μmol m-2s-1). However, it is possible to reduce N fertilization by 25% (56 mg N plant-1day-1) without affecting monthly flower production and quality variables (no significant differences were found between treatments (P>0.05)).