Abstract
The physic nut (Jatropha curcas L.) has great potential for use in biodiesel production due to the high oil content of its seeds. Production of high quality seeds depends upon the appropriate time of harvest. A field experiment was carried out to monitor the maturation process of physic nut seeds and to establish the ideal harvest time of the seeds based on external fruit color. Fruits were collected at different maturation stages based on the external color: green, yellow-green, yellow, yellow-brown and brown. Seeds were extracted manually and, after natural drying, were submitted to the following tests and determinations: moisture content and dry matter, germination, first count seedling emergence, seedling growth, accelerated aging, electrical conductivity, the weight of thousand seeds and oil content. A randomized design was used with four replications. Data were subjected to analysis of variance and, for each test, treatment means were compared by Tukey test at 5% probability. Physic nut seeds with high physiological quality are obtained from yellow and yellow-brown fruits. Seeds from green fruits have lower physiological quality, dry matter and oil content than the other maturation stages. The seeds obtained from brown fruits have a high germination potential, but have low vigor in relation to yellow and yellow-brown stages.
Highlights
Jatropha curcas L. (Euphorbiaceae) commonly known as the “physic nut”, is a tropical shrub with seeds rich in oil that meet the standard for use as biodiesel (TIWARI et al, 2007)
The seeds were dried at room temperature to approximately 8% moisture content and the following parameters were determined for each maturation stage: 1000-seed weight: eight replications of 100 seeds were weighed (0.0001g) and 1000-seed weight was determined according to procedures described by Rules for Seed Testing (BRASIL, 2009)
When the fruits turned brown seed moisture content declined to 17.7% reaching values between 7.6 to 8.3% after natural drying at room conditions (Table 1), independent of the harvest stage
Summary
Jatropha curcas L. (Euphorbiaceae) commonly known as the “physic nut”, is a tropical shrub with seeds rich in oil that meet the standard for use as biodiesel (TIWARI et al, 2007). (Euphorbiaceae) commonly known as the “physic nut”, is a tropical shrub with seeds rich in oil that meet the standard for use as biodiesel (TIWARI et al, 2007). The plant can be propagated through cuttings, seed propagation is more common. Information regarding seed production and technology, especially regarding seed maturation, are scarce. Fruit harvesting at an adequate maturation stage is one of the factors that determines seed quality. Determination of the stage of maximum seed quality during fruit development is essential, especially in plant species such as physic nut that have indeterminate fruiting periods (SILIP et al, 2010). Obtaining high quality seeds in such species is difficult because fruits at different developmental stage are found on the same plant and in the same fruit
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