Studies on variation of seed and seedlings characteristics of neem Azadirachta indica A. juss from different seed sources in Sudan.

Abstract

The main aim of the present work was to assess the variation of the neem provenances and their extended areas and the adaptation to the different eco-climatic conditions in its occurrences in Sudan. The specific objective was to study the variation in seed morphometric characteristics, seedlings growth performance and drought tolerance among seven neem (Azadirachta indica A. Juss) provenances (Elfasher, Elobied, Bara, Eldalang, Abassya, Senga and Gedaref) representing western, central and eastern parts of the country. Three experiments were performed to fulfill the objectives of the study. The first two experiments were conducted at the lab of the nursery of the Regional Tree Seed Center, Elobied Sudan, while the third was carried out at the nursery of the Faculty of Natural Resources and Environmental Studies, University of Kordofan. The first experiment, investigated seed morphometric and physiological characters (seed weight, number of seed/kilogram, seed length, seed width, seed moisture content and effect of normal and cool storage on seed germination percentage and its variation among the seven provenances). The second experiment investigated was conducted in seedling growth in nursery pots using Completely Randomized Design (CRD) with five replicates for seedling parameters measurement (root collar diameter, shoot length, root length, root fresh weight, number of leaves, leaf area, shoot/root length ratio, root dry weight, root fresh weight). The third experiment investigated the variation in drought tolerance in four selected provenances (Elfasher, Eldalang, Senga and Gedaref). A factorial experiment in a CRD with three replications was used by applying four level of irrigation regimes (25%, 50%, 75% and 100% Field capacity (FC)) and two soil types (sand and clay soils). Measurements of seedling parameters were recorded using destructive sampling method. The obtained data from the three experiments was analyzed using analysis of variance and SAS software version 6.12. and the means were separated using Duncan New Multiple Range Test. Results obtained from the analysis showed significant variations between the provenances in most of the measured variables indicating that neem tree in Sudan is adapted to the different eco-climatic zones in Sudan. In this regard, Elfasher provenance is excelled in having significantly superior morphometric characteristics (seed length, seed width) and recording the least number of seed per kilogram, which is vice versa in Gedaref provenance. The storage and moisture content experiments showed that Abassya provenance seeds have the highest moisture content (9.7%) with least germination percentage (%) in both normal and cool conditions. While seeds from Bara, Senga and Elfasher recorded the highest germination percentage (%) (moderate/least moisture content). The provenances showed high significant (p<0.0001) in growth performance (root collar diameter), however, there is no significant in leaf area among the provenances. Elfasher provenance showed significant (p<0.0001) in the seedling parameters (root length and leaf area), while Senga provenance is significant only with seedlings length. It is concluded that a multi site field provenance trial is required for more useful information about the studied seed sources for the eco-climatological adaptations. The obtained from the experiment of drought tolerance seedlings of different seed sources showed clear trend of adaptation with provenances (smaller root collar diameter). The study revealed that then was substantial variation between the seed sources provenances in their ability to tolerate induced drought in the early growth stages thus helping for better selection of planting materials of neem suite that can the different environmental conditions regarding rainfall. In this study it was clear found that the neem tree in Sudan, although it is generated from one tree (in Shambat), it established in different provenances in various geographical locations and ecotype over Sudan, due to its adaptation ability.