Light intensity variation and early growth performance of <i>Anona muricata Linn</i> seedlings in south-western Nigeria

Abstract

The study was carried out in the Silviculture nursery of Forestry Research Institute of Nigeria (FRIN), Jericho, Ibadan, Nigeria. Fruits were collected  from Ogun, Osun, Ondo and Oyo States. The seeds were extracted, air dried and seedlings raised. Each seedling was transplanted into a polythene  pot filled with top soil. . A total of 160 seedlings were exposed to four different light intensities (100%, 75%, 50% and 25%) under light screening chambers made from wooden frames and covered mesh on all sides with single, double or triple layers of synthetic 1mm mesh netting. The  seedlings raised in the open nursery were receiving 100% light intensity and served as control. Seedlings were watered daily. Growth variables were taken fortnightly for eight months. The seedling height, collar diameter and number of the leaves were assessed. The results showed that the number of leaves of Anona muricata varied significantly among the three factors and the control. The highest number of leaves was found in seedlings exposed to 100% (23.2), 75% (20.65), 25% (20.2) and 75% (20.4) light intensities for seedlings raised from seeds from Ogun, Ondo, Osun  and Oyo respectively. The least leaf number was found in 25% (19.9), 50% (19.25), 50% (2318.0) and 100% (19.5) in Ogun, Ondo, Osun and Oyo States respectively. The ANOVA revealed that there were no significant differences at 5% probability level in all the four seed sources. The highest diameter was found in seedlings exposed to 100% (4.47 mm), 75% (4 mm), 100% (4.14mm) and 75% (3.90 mm) light intensities in Ogun, Ondo, Osun and Oyo States respectively while the least was observed in 25% (3.06mm), (3.60 mm), (3.61 mm) and (3.36 mm) in all states. There were significant  differences at 5 % probability level among the treatment in Ogun, Osun and Oyo States while in Ondo State, there was no significant difference at 5% probability level. The highest height was found in 75% (31.01 cm), (32.44 cm), (31.69 cm) and (33.43 cm) light intensity while the least was found in 25% (21.01 cm), (22.46cm), (25.28cm) and (22.86 cm) light intensity in all sources. The ANOVA revealed no significant differences at 5% probability level in all the four sources used. Therefore, it was concluded that A. muricata requires partial shade (75 % light intensity) and seeds from Oyo State were found best among the sources.

Keywords: Light intensity, Annona muricata, southwestern Nigeria, early growth performance