Comunicata Scientiae

Ecophysiology of the Southern Highbush blueberry cv. Biloxi in response to nitrogen fertigation

2020-03-16T01:51:47+00:00

In Brazil, the nutritional requirements of the blueberry are not sufficiently known, thus requiring further research on the management of mineral fertilization. In this perspective, this work aimed to evaluate physiological attributes of Southern Highbush blueberry plants cv. Biloxi as a function of nitrogen fertigation in Brasília-DF. The experiment was conducted from August 2018 to July 2019, in the Fruit Sector of the Experimental Biology Station of the University of Brasilia (UnB), Federal District. This experiment adopted a randomized block design, with four treatments: 10; 20; 30, and 40 g of N plant-1, 8 replications, and 5 plants per experimental plot. The following variables were measured: net photosynthesis rate (A), transpiration (E), stomatal conductance (gs), internal CO2 concentration (Ci), instantaneous water-use efficiency (WUE), carboxylation efficiency (CE), SPAD index (SPAD) and leaf nitrogen (N). There was an effect of the different nitrogen doses applied on the physiological attributes. The plants of the blueberry cultivar Biloxi increased their photosynthetic rates at doses up to 30 g of N plant-1. Nitrogen rates did not influence stomatal conductance nor did they provide improvements in the carboxylation efficiency of the blueberry plants. Under the conditions of the present work, the highest N leaf contents were obtained with the application of 30 g N plant-1, and values above this concentration did not correspond to higher net photosynthesis rates, transpiration, and CO2 concentration in the leaf mesophyll.

Physiological indices and phytomass partition in precocious dwarf cashew clones irrigated with saline waters

2020-03-16T01:47:14+00:00

This research aimed to evaluate the physiological indices and the accumulation of phytomass in clones of precocious dwarf cashew under salt stress during rootstock formation. The experiment was conducted in greenhouse in the municipality of Pombal-PB. The experimental design was in randomized blocks, and the treatments were organized in a 5 x 3 factorial arrangement, constituting the levels of electrical conductivity of the irrigation water - ECw (0.4 -Control; 1.2; 2.0; 2.8, and 3.6 dS m-1) and the clones of precocious dwarf cashew (Faga 11, Embrapa 51, CCP 76), with three replications and two plants per plot. Water salinity higher than 0.4 dS m-1 resulted in a decrease of the relative growth in plant height, leaf area, and phytomass accumulation in the cashew plant. The cashew clones are sensitive to water salinity from 0.4 dS m-1. Among the physiological indicators, the leaf area ratio, the sclerophylly index, and the root/shoot ratio of the precocious dwarf cashew are highlighted as salt stress indicators. The use of water with 0.4 dS m-1 of electrical conductivity is recommended for the formation of cashew rootstocks.

Management of soil cover and its influence on phytosociology, physiology and fig production

2020-03-12T20:02:24+00:00

The fig stands out as an important source of food for the human diet, especially minerals and fibers. Weeds are a major concern in the conduct of fig orchards. Therefore, the objective of this study was to evaluate the effect of management of vegetable cover of soil (CVS) on weed phytosociology, physiological characteristics and fig production. The experimental design was a randomized complete block design with four replications. The treatments consisted of six CVS managements: cover maintenance, weeding, lodging, mowing, application of herbicides diquat and glyphosate. For the constitution of the vegetal cover a consortium of three winter forage species, vetch and black oats sowed and the ryegrass remaining in the area of previous years were used. Thus, we evaluated the phytosociology of weeds present in the area, at two different times, assigning parameters related to frequency, density and abundance, which establish the species importance value index (IVI), besides the dry mass of the aerial part of the weeds. Physiological parameters and total fruit yield were evaluated at the end of the crop cycle. The different CVS management methods influenced the weed community, mainly in the diversity, density and dry mass of the aerial part. There is no interference in the physiological variables of the fig plants and in the total production of fig fruits. We highlight the maintenance of coverage and lodging as the most promising for the management of weeds found fig orchards.

Physiological responses of beet plants irrigated with saline water and silicon application

2020-03-26T20:54:12+00:00

Although not considered an essential element, silicon can be used to increase crop productivity, especially under stress conditions. In this sense, the objective was to evaluate the gas exchange of beet plants irrigated with saline water depending on the application of silicon. The experiment was conducted in a randomized block design, in a 5 x 5 factorial, referring to five levels of electrical conductivity of irrigation water (ECw): (0.5; 1.3; 3.25; 5.2 and 6.0 dS m-1) and five doses of silicon (0.00; 2.64; 9.08; 15.52 and 18.16 mL L-1), with six beet plants as an experimental unit. The effect of treatments on beet culture was evaluated at 30 and 60 days after irrigation with saline water from measurements of internal carbon concentration, stomatal conductance, net photosynthesis rate, instantaneous water use efficiency and instantaneous carboxylation efficiency using the LCpro+Sistem infrared gas analyzer (IRGA). Irrigation with saline water reduced the gas exchange of beet plants at 60 days after irrigation, but at 30 days after irrigation, the use of saline water increased stomatal conductance, transpiration rate and internal carbon concentration. The application of silicon decreased stomatal conductance, internal carbon concentration and efficiency in the use of water, but increased the rate of net photosynthesis, the rate of transpiration and instantaneous efficiency of carboxylation at 30 and 60 days after irrigation.

Production of Formosa papaya seedlings irrigated with wastewater and application of biostimulant

2020-04-04T16:34:21+00:00

Papaya (Carica papaya L.) is one of the leading fruit trees in Brazil, mainly in the Northeast region. However, some regions suffer from water scarcity, making wastewater reuse a viable alternative for crop production. Also, biostimulants may be used to maximize papaya growth and development. Thus, this work aimed to evaluate the use of Acadian® biostimulant in the growth of Formosa papaya seedlings irrigated with different concentrations of fish-farming wastewater. The experiment was block randomized in a 2 x 5 factorial scheme, use and non-use of biostimulant and five concentrations of wastewater (0, 10, 20, 30, and 40%) diluted in potable water, with four replicates. Qualitative data were compared by t-test at 5% probability, and quantitative data were submitted to regression analysis. Results showed that high concentrations of wastewater negatively affect the production of Formosa papaya seedlings. Acadian® negatively influences plant height, number of leaves, and the ratio between shoot and root. However, the seaweed biostimulant positively influenced the chlorophyll content index.

Grafting methods and use of fasteners in monoembryonic, polyembryonic, and multi-stemmed jaboticaba (Plinia jaboticaba (Vell) Berg) seedlings

2020-04-04T16:51:33+00:00

Jaboticaba is a native fruit from Brazil, appreciated for its sweet taste and organoleptic characteristics. The propagation of this fruit species occurs exclusively through seeds, which present high germination rates, although with a long period of juvenility, a fact that favors advances in studies aiming at an early fruiting. This research aimed to study a more adequate and rapid grafting method for the jaboticaba cv. Sabará. The experimental design was in randomized blocks, with 12 treatments consisting of combinations using three types of seedlings (monoembryonic, polyembryonic, and multi-stemmed), two grafting methods (top cleft and splice grafting), and two fasteners (parafilm® tape and circular clip), with three replications consisting of 10 seedlings each. The analyzed characteristics were: monoembryony (%); polyembryony (%), multi-stemming (%), grafting success rate (%), survival (%), scion length (cm), scion diameter (mm), and rootstock diameter (mm). The percentage of monoembryony (46.4%) was higher than the success rates of polyembryony (36%), and multi-stemming (17.6%). The top cleft grafting method of monoembryonic seedlings fastened with parafilm® and circular clip, and polyembryonic seedlings fastened with circular clip were the more suitable for grafting in the jaboticaba cv. Sabará.