Rapid and Effective Methods for Breaking Seed Dormancy in Buffalobur (Solanum rostratum)

Abstract

The spread of buffalobur in China poses a serious threat to existing ecosystems, and control and eradication of this species have become increasingly important. Studies were carried out to ascertain the seed production, morphological characterization, dormancy behavior, and methods for breaking dormancy of buffalobur. The results showed that a single buffalobur plant could produce 1,600 to 43,800 seeds with an average weight of 3.0 mg. Average seed length, width, and thickness were 2.5, 2.0, and 1.0 mm, respectively. Newly ripened buffalobur seeds were innately dormant and exhibited combinational dormancy, which involves a hard seed coat (physical dormancy, PY), a partial dormant embryo (physiological dormancy, PD), and a dark requirement to germinate. PY of buffalobur seeds could be broken by dehusking or acid scarification by 14 M H2SO4for 15 min, with germination rates of 55 or 50%, respectively. PD was effectively broken by KNO3or gibberellic acid (GA3). The optimum concentration for KNO3was between 20 and 40 mM, which resulted in over 70% seed germination. When presoaked with GA3at 30 C in dark for 24 h, maximum germination (> 98%) was obtained at 2.4 mM, the corresponding germination speed (85%) and germination index (16) were also highest at this concentration. Synergistic effects were observed in seed germination when H2SO4and GA3were combined. The most rapid and effective combination in breaking dormancy was when the seeds were immersed in H2SO4(14 M) for 20 min and presoaked with 2.4 mM GA3for 24 h. Germination index for this combination was over 35, and 95% of the seeds germinated within 7 d. Knowledge gained in this study will be useful in increasing germination of buffalobur and facilitating further laboratory studies.