Germinação e crescimento inicial de genótipos de mamoneira com sementes submetidas ao envelhecimento acelerado.

Abstract

The castor plant there a long time is considered a culture of great importance is for the Northeast of Brazil, has been winning great prominence at present time, due to the chemistry ricin progress, with diversity of applications in the industry and for the exploration as natural and renewable source of energy, in the biodiesel production. One of the largest impediments faced in the castor plant production is scarce use of improved seeds and of high quality; due to little knowledge and diffusion on such materiais and for the high obtaining cost. Based on this, the objective of work was to evaluate in four castor bean genotypes, being a variety (BRS 149 Nordestina) and three hybrids (Savana, Lyra and Iris), his establishment capacity, with and without the induction of the accelerated aging of seeds and initial growth. The experiment was conducted in the National Center of Research of the Cotton (EMBRAPA/CNPA), in Campina Grande, PB, in conditions of greenhouse, in the period of August to December of 2004. The experimental design was in randomized blocks, with factorial scheme 4x2, being four genotypes and two treatments of the seeds (normal and with accelerated aging), in four replications. The analyzed variables were: initial germination and vigor, plant height, stem diameter, leaf area, phytomass of root and of shoot and shoot to root ratio. With the primary data of height, diameter and leaf area, were determined the absolute and relative growth rates of the plants. The accelerated aging reduced the germination significantly in 12% and the vigor in 22%, of the seeds of the castor bean genotypes studied, and it affected the growth of the plants of ali the genotypes negatively along the studied times. The largest germination Indexes and vigor went to BRS 149 Nordestina (91 and 83%) and normal seeds (92 and 79%). In relation to the height of the plants, the superiority was of the genotype BRS 149 Nordestina and normal seeds, with an increment 12%. The stem diameter of genotypes little varied, with superiority of BRS 149 Nordestina in relationship the hybrid Savana, Lyra and Iris of 7; 13 and 10,5%. Beanning from the 37 days, the normal plants had an increment of approximately 6,7% in the stem diameter. The smallest phytomass values root and shoot were observed for the íris. The shoot to root radio and the volume of root went superiors to BRS 149 Nordestina.