MEDEIROS, J. E.; http://lattes.cnpq.br/7559810599178406; MEDEIROS, Joyce Emanuele de.
Resumo:
Parthenocarpy in watermelon adds value to fruits, however, for its cultivation, the producer
may encounter difficulties such as: adaptation of hybrid to regional conditions, high seed
prices, low germination and seedling vigor, beyond the need to cultivate, in the same area, a
diploid variety as source of pollen for triploids. Thus, the objective was to evaluate the effect
of application of cytokinin CPPU at different concentrations, in the induction of fruiting
partenocarpic in diploid and triploid watermelon plants. The study comprised two field
experiments conducted in the field in Campus of UFCG in Pombal -PB, from 12/15/2012 to
03/02/2013 using the triploid hybrid 'Extasy' and diploid variety 'Crimson Sweet'. For both
experiments, treatments consisted of five concentrations of growth regulator CPPU (0.75, 1.0,
1.5, 2.5 and 3.5 mg L- 1
) and the control (natural pollination). The experimental design was a
complete randomized block designed with four replications. The application of CPPU
occurred exogenously in the ovary of flowers for two consecutive days at anthesis. The
variables evaluated were: photosynthetic rate (A), stomatal conductance (gs), transpiration
(E), intercellular CO2 concentration (Ci), water use efficiency (EUA), chlorophylls,
carotenoids, number of leaves, leaf area, dry mass of leaves, stem and fruit and total dry
matter, total and marketable yield, average weight of marketable fruit , number of fruits per
plant, number of marketable fruits per plant, fruit shape index, shell thickness and pulp,
soluble solids, titratable acidity, pH, SS/TA and ascorbic acid. The CPPU was efficient in
inducing fruiting of diploid watermelon 'Crimson Sweet' and triploid 'Extasy’, regardless of
the concentration used. The concentration 2.5 mg L- 1
of CPPU applied in diploid watermelon
provided the greatest number of marketable fruits per plant, higher total and marketable yield
production compared to control, and in the triploid plants in increased the number of fruits per
plant, number of fruits marketable per plant, total production and commercial production
compared to control. Induction of fruiting with CPPU in watermelon ‘Crimson Sweet’ had no
effect on dry matter accumulation, growth and physiological characteristics of the plant
compared to the control. In 'Extasy', CPPU provided a greater accumulation of dry matter in
the fruit decreased dry mass of leaves, stem and plant growth, increase in stomatal
conductance and CO2 assimilation compared to the control. In watermelon 'Crimson Sweet'
the concentration of 2.5 mg L- 1
yielded higher stomatal conductance, photosynthetic rate and
dry matter accumulation in the fruit. In watermelon 'Extasy', concentrations of CPPU were
indifferent gas exchange and plant growth.