Aline Ramm

The chlorophyll a fluorescence as an indicator of the temperature stress in the leaves of Prunus persica

Plants growing in temperate regions are often exposed to stress conditions caused by high temperatures. Photosynthesis is one of the metabolic processes most sensitive to high temperature stress, and it is often inhibited before other cellular functions. Using peach leaf disks, we studied the transient chlorophyll a fluorescence along with the gas exchanges at temperatures of 25 (control) 30, 35, 40 and 45°C in the dark for a period of 30 minutes. Temperatures above 35°C caused significant changes in the transient fluorescence of chlorophyll a, including an increase in the initial fluorescence (F0), a decrease in maximum fluorescence values (FM) and the appearance of K and L bands. The values of the net assimilation rate decreased as the temperature increased and reached negative values at 45°C.

Crescimento e fotossíntese de plantas de pinhão-manso cultivadas em diferentes condições de luminosidade

Jatropha curcas L. has been prominent in the scenario of biodiesel due to the percentage of oil contained in the seeds and its adaptive capacity. The cultivation of J. curcas in the country has as proposal the agronomic development and its consortium may be important for small producers. This study aimed to characterize the phenological behavior of J. curcas grown under different light conditions, full sun and 50% shade, relating them to the climatic seasonality, comparing their development with chlorophyll a fluorescence and gas exchange. Plants showed vegetative growth with seasonal pattern, with growth peak at the beginning of March, when the leaf senescence began. The analysis of the kinetic of the transient fluorescence of chlorophyll presented a relationship between certain parameters of the test JIP and the environmental fluctuations. The PIABS and the PItotal demonstrated that in the shaded treatment plants were sensitive to luminosity reduction. The liquid assimilation rate and the carboxylation efficiency decreased throughout the experiment, accompanying the decline of the solar radiation. J. curcas plants respond negatively to these shaded conditions.

Carvão ativado no estabelecimento in vitro de cultivares de framboeseira

Propagation of raspberry (Rubus idaeus L.) is usually performed from root cuttings. Although fruits have viable seeds, sexual reproduction is unwanted due to the high genetic variability and long juvenile period besides dormancy, which causes plant development to be slow and consequently produces the same result in the production of new seedlings. So, in vitro micropropagation is a viable technique for seedling production, thus maintaining genetic features of the mother plant, uniformity, precocity of production, as well as accelerating the conventional propagation methods, are an alternative to planters. The aim was the evaluation of the effect of different concentration ratios of activated charcoal supplied in the growth medium on the different raspberry cultivars. Activated charcoal was used (0; 2; and 4 g L-1), and the raspberry cultivars were (Indian Summer, Heritage, Willamette, Golden Bliss, Polana, Fallgold, Schonemann, and Bababerry). The best oxidation control was presented on cultivars Golden Bliss, Polana, Fallgold, Schonemann, and Bababerry, grown on cultivation medium added of 4 g L-1 activated charcoal, due to the absorption of phenolic compounds released into the culture medium.

Development of 'Maciel' peach trees on different propagation systems.

The development of new technologies for seedling production is essential in fruit growing. In this context, the objective was to compare vegetative and productive aspects of ‘Maciel’ peach trees and the quality of fruits from plants under different propagation systems. The experiment was carried out in a randomized complete block design with four replications, in a 2 x 3 factorial scheme, two years (2014 and 2015) and three propagation systems (self-rooted ‘Maciel’ (minicutting), ‘Maciel’ with rootstock ‘Okinawa’ (minicutting) e ‘Maciel’ with rootstock ‘Okinawa’ (seed)). The variables evaluated were canopy volume, trunk diameter, yield, productive efficiency, fruit diameter, soluble solids (SS), titratable acidity (TA), SS/TA ratio, pH, pulp firmness, carotenoids, phenolic compounds and antioxidant capacity. The self-rooted ‘Maciel’ peach plants, in the second year of evaluation, present higher canopy volume, trunk diameter and thus, they express higher yield and productive efficiency. Fruit quality how much soluble solids, titratable acidity, SS/TA ratio, pH and pulp firmness are not altered by different propagation systems. The use of different propagation systems over two years modifies the levels of carotenoids and phenolic compounds total and, consequently, the antioxidant capacity of the fruits of ‘Maciel’ peach plants.