Abstract
With increasing global energy demands, the production of biofuels has been gaining economic importance, with the castor oil plant being one option for the production of biofuel. This study was performed on irrigated cultivation of the castor oil plant, variety IAC 2028, from March to October 2011, in Lavras, Minas Gerais, Brazil, with the following aims: a) to characterise and estimate the sub stages and stages of the crop in days after sowing (DAS) and in growing degree days (GDD) and; b) determine a phenological model of development that describes the vegetative and reproductive behavior of the crop cycle. The experiment was conducted under optimal conditions of irrigation and fertilisation. To determine the phenological model, 15 sub stages and 4 stages of the crop were defined and estimated according to the periodic quantification of variables such as the number of leaves, leaf area, soil cover, and periods of floral initiation, anthesis, bean formation, and maturation by raceme order. We concluded that: a) the sub stages were well characterised and estimated, in particular Vo, A2, M2, and M3, which closed stages I, II, III, and IV with nearly 42, 65, 87, and 100% of the thermal power required by the crop during the lifecycle, respectively; b) the phenological model of the sub stages was determined satisfactorily in GDD; and c) the plant and reproductive sub stages were not completely distinguishable, and the maximum soil cover in M1 indicated that greater productivity could occur with a population increase. Key words: Ricinus communis L., phenological model, phytomass, soil cover fraction, leaf area index.
Highlights
IntroductionIn Brazil, and in particular in the southern region of the state of Minas Gerais, information is lacking regarding the interaction of the castor oil plant with local climatic conditions, water requirements and, in particular, there is a lack of studies on the technical and economic factors affecting its production potential
This study was performed on irrigated cultivation of the castor oil plant, variety IAC 2028, from March to October 2011, in Lavras, Minas Gerais, Brazil, with the following aims: a) to characterise and estimate the sub stages and stages of the crop in days after sowing (DAS) and in growing degree days (GDD) and; b) determine a phenological model of development that describes the vegetative and reproductive behavior of the crop cycle
For cultivation under normal conditions there is a difference of 10 days between sowing and emergence; the timing of initial primary, secondary, and tertiary flowering and productive sub stages differed, respectively, by 20, 29, 44 and 30 days from the values of 70, 85, 105, and 180 days after emergence found by Savy Filho et al (2007)
Summary
In Brazil, and in particular in the southern region of the state of Minas Gerais, information is lacking regarding the interaction of the castor oil plant with local climatic conditions, water requirements and, in particular, there is a lack of studies on the technical and economic factors affecting its production potential. In this region, the average productivity of 1,310 kg ha-1 is higher than the national average, but is lower than the state average productivity of 1,355 kg ha-1 (Silva et al, 2010). This study had the following objectives: a) to characterise and estimate the substages and stages of the castor oil plant based on time and temperature using phenological variables; b) to determine a phenological model of development; and c) to describe the vegetative and reproductive behavior of the crop under the climate conditions of the municipality of Lavras, Minas Gerais, Brazil
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