Germination and Post Emergence Growth of Lime (Citrus aurantifolia Swingle) as Affected by Seed priming with Growth Regulators and Bio-stimulants

Abstract

Lime is of widest distribution in Sudan compared to the other members of the citrus group. As it is conventionally propagated by seeds, this study aimed to investigate the possibility of enhanced germination and seedling growth attributes upon lime’s seed priming with growth regulators and bio-stimulants in two separate tests under the conditions of the nursery. The regulators test was for gibberellic acid (GA3) and naphthalene acetic acid (NAA) each in concentrations of 0, 5, 10, 15 and 20 mg/l. In the second test, the priming potential was tested for solutions of the hot water extracts of Argel shoots (Solenostemma argel Del Hayne) in concentrations: 0, 5, 10, 15 and 20 g/l, and the gel extracted from the leaves of Aloe (Aloe vera) plants in concentrations: 0, 10, 20, 30 and 40%. In both trials, the completely randomized design was used with 4 replicates. Except the 5 mg/l treatments of both regulators –in some cases- the other concentrations resulted in significant increases in germination and seedling growth parameters compared to the control. In particular, GA3 was most enhancive for germination %, leaf length and width, while seedling height was promoted by the 15 mg/l NAA treatment. The results elucidate the bio-stimulating potential of Argel and Aloe applications at certain level. Although the 15% Argel and 20% Aloe were best enhancers for germination %, the highest concentrations from each were of poorest effect. The longest seedlings resulted at an equal statistical level from the 10 and 20% Aloe and the 5 and 10 mg/l Argel concentrations. The lower Argel concentrations (5 and 10) were inductive to leaf attributes, whereas Aloe at 30 and 40% were of particular impact on length. The findings of the study propose the use of the two plants as seed primers for enhanced germination and seedling growth attributes of lime. Yet, confirmatory trials with seeds of other horticultural crops might be justified in efforts towards organic farming.