Open Access Original Research Article

Chilling Requirement of Ten Peach Cultivars Estimated by Different Models

C. G. Milech, M. Dini, S. Scariotto, J. Santos, F. G. Herter, M. C. B. Raseira

Journal of Experimental Agriculture International, Page 1-9
DOI: 10.9734/JEAI/2018/39204

The adaptation of a temperate climate fruit cultivar to a certain area depends mainly on its chilling requirement and the chilling accumulation in such places. Several attempts have been made to estimate these two conditions, using different models. The great variation among the models to calculate chilling requirement makes it necessary to determine their efficiency in a given location. Aiming to estimate the chilling requirement of ten peach cultivars, including Bonão, Pepita, Maravilha, Precocinho, Turmalina, Diamante, BR-3, Marfim, Coral, and Cambará do Sul, seven models were tested: Utah, Positive Utah, Low Chill, Taiwan, Chilling Hours (≤7.2°C), Chilling Hours (≤11°C), and Dynamic. The results showed that the estimation of chilling accumulation for all the studied cultivars in all the tested models showed a large variability. None of the tested models was perfect for estimating the chilling requirement, especially considering the variable climatic conditions of southern Brazil. Except for the Utah model, any of the others can be used to provide a rough estimate of the chilling requirement of the cultivars; however, the Taiwan and Low Chill models seem to be more suitable. The chilling requirement, which was estimated based on the average over the 11 years of the study, overestimated the real need, when compared to the yields over those years. There are differences among the studied cultivars; however, with the exception of Cambará do Sul, all the others can yield good crops and show good adaptation to the climatic conditions of the southern Rio Grande do Sul.


Open Access Original Research Article

The Irrigation Deficit and Its Effects on Physiology and Phenology of ‘Navelate’ Oranges Trees in Brazil

C. R. M. Oliveira, P. C. Mello-Farias, D. Agostinetto, R. R. Yamamoto, L. O. D. Marques

Journal of Experimental Agriculture International, Page 1-9
DOI: 10.9734/JEAI/2018/38519

Aims: The aim of this research was to study physiological responses and changes on phenology of ‘Navelate’ orange trees submitted to different water stress intensities in a greenhouse.

Study Design: The experimental design was completely randomized, with three replications in each experimental unit. Values of each parameter were submitted to variance analysis, compared by Tukey’s test at 5% significance and showed as averages.

Place and Duration of Study: The experiment was carried out in a greenhouse (latitude 31°52'00 "S, longitude 52°21'24" W, 13 m above sea level), during 2014 and 2015.

Methodology: Stressed conditions were based on 50% and 25% of the field capacity. Gas exchange [photosynthesis (A), transpiration (E), stomatal conductance (gs), water use efficiency (WUE)] were analyzed using an infrared gas analyzer, model Li-6400 (Portable Photosynthesis System LICOR, Nebraska, USA), in addition to growth parameters.

Results: Reductions on photosynthetic rate were observed (10.74% for T-50, and 20.66% for T-25, both compared to Control), indicating that CO2 assimilation rate was affected by water stress conditions. Water stress affected all gas exchange parameters of the exposed orange trees, limiting growth in diameter and height. Fruit yield decreased with the amount of water (100%> 50%> 25%).

Conclusion: Navelate orange plants exposed to water deficit were tolerant in the initial phase of the treatments and during the vegetative phase, being more sensitive in the reproductive period. Plants submitted to stress with 25% of field capacity, presented limitations compared to control plants under full water availability, such as differences in height, diameter and fruit production. Water stress, at any level, reduced plant growth and fruit production. Therefore, due to variations in phenological parameters among the treatments, further studies should be performed on these variables to search for water deficit tolerant varieties and quality fruits production under these conditions.

Open Access Original Research Article

Drain Envelopes for Problematic Calcareous Soils of Irrigated Agricultural Lands in Egypt

Gehan A. H. Sallam

Journal of Experimental Agriculture International, Page 1-13
DOI: 10.9734/JEAI/2018/39072

Envelope materials are used for surrounding subsurface drain pipes commonly installed to reclaim waterlogged and salt-affected lands to prevent entry of soil particles into drains and to constitute a medium of good permeability around the pipe and therefore reduce entrance resistance. In calcareous soils prone to the reduction of drainage capacity as a result of high clogging, determining adequate envelope materials is a crucial issue under Egyptian conditions. The study was conducted on a calcareous soil with a high risk of calcium carbonate precipitation. Four drain-envelope combinations of subsurface drainage systems were tested in an experimental field. It came out that granular and pre-wrapped drain envelopes, with a normal grade of 10cm/100m, were the best material regarding their hydraulic and mechanical performance for sub-surface drainage in calcareous soils.


Open Access Original Research Article

Biodegradable Coatings on Blueberries Postharvest Conservation Refrigerated in a Modified Atmosphere

Ícaro Pedroso de Oliveira, Aline dos Reis Ribeiro, Paulo Mello-Farias, Marcelo Barbosa Malgarim, Mírian Ribeiro Galvão Machado, Carlos Sebastián Pérez Lamela

Journal of Experimental Agriculture International, Page 1-11
DOI: 10.9734/JEAI/2018/39138

Aims: The aim of the present study was to evaluate the effect of edible coatings based on manioc starch, kefir and chitosan on the physicochemical and microbiological characteristics of blueberry subjected to refrigerated storage in a modified atmosphere.

Study Design:  The experimental design was completely randomized in a two-factorial scheme.

Place and Duration of Study: Department of Crop Science, Fruit Science Laboratory, Faculty of Agronomy Eliseu Maciel and Center for Chemical Sciences, Pharmaceutical and Food, Federal University of Pelotas, between October 2015 and September 2016.

Methodology: The treatment factors were composed of edible coating (cassava starch, Kefir, chitosan and uncoated, which corresponded to the control), and the periods of refrigerated storage in a BOD chamber simulating the shelf life (9, 18, 27, 36 days). The physicochemical analyses were a mass loss; texture; color parameters (L, a*, b* and Hue); soluble solids (SS); pH; titratable acidity (TA); and SS/TA ratio. In addition, total and thermotolerant coliforms were counted and the presence or absence of Escherichia coli and Salmonella spp. were observed.

Results: Edible coatings based on kefir grains and chitosan maintained the physicochemical characteristics of blueberry during refrigerated storage in modified atmosphere. Fruits are in compliance with the microbiological standards established by the legislation.

Conclusion: Extending storage time of chilled blueberries under a modified atmosphere promotes an increase in mass loss after application of the coatings and after 27 days.

Open Access Original Research Article

Productivity and Economic Viability of Carrot Fertilized with Calotropis procera in Different Growing Seasons

Bruno Novaes Menezes Martins, Ênio Gomes Flôr Souza, Manoel Galdino dos Santos, Michele Barboza, Aurélio Paes Barros Júnior, Lindomar Maria da Silveira, Francisco Bezerra Neto

Journal of Experimental Agriculture International, Page 1-13
DOI: 10.9734/JEAI/2018/39251

The objective of this work was to evaluate the productivity and economic viability of the carrot as a function of different amounts and times of incorporation to the soil of the green manure roostertree (Calotropis procera) in two growing seasons, in the semiarid region of Pernambuco, Brazil. The study was conducted in an experimental field belonging to the Federal Rural University of Pernambuco (UFRPE), in the autumn–winter (March to July 2012) and spring–summer (September 2012 to January 2013) periods. The experimental design was in randomized blocks, with three replications. The treatments were arranged in a 4 x 4 factorial scheme, with the first factor consisting of four amounts of roostertree biomass (5.4, 8.8, 12.2 and 15.6 Mg ha-1 on a dry basis), and the second factor consisting of four incorporation times of this fertilizer into the soil (0, 10, 20 and 30 days before sowing the carrot). The commercial productivity of carrot roots and production costs were evaluated, in addition to the following economic indicators: gross return, net return, rate of return and profit margin. The cultivation of the carrot fertilized with roostertree was economically viable, regardless of the quantity of green manure, of the time of incorporation into the soil or the time of cultivation. In autumn–winter, the lowest amount of roostertree (5.4 Mg ha-1) associated with the incorporation time of 10 days before planting the carrot was considered ideal for the agro-economic viability of the crop. The carrot cultivation in spring–summer was most profitable when fertilized with 14.0 Mg ha-1 of roostertree on the same day of carrot planting.