Effect of application of NPK fertilizer and bending of the mother plants on the suckering ability of selected Coffee Wilt Disease resistant Robusta coffee (Coffea canephora) varieties in Uganda

Abstract

In response to the outbreak of Coffee Wilt Disease (CWD) in the 1990’s and 2000’s which killed nearly half of the Robusta coffee in Uganda, causing losses of about US$100 million, the National Agricultural Research Organization (NARO) released 10 CWD-r resistant varieties or Kituza Robusta (KR’s). These varieties are being mass produced by cloning though, KR1, KR3 and KR4 have been reported to have poor suckering ability. An on-station study was therefore conducted to determine the effect of NPK fertilizer and bending angle of mother plants on suckering ability of these varieties. A split plot design with three replications was used, with fertilizer levels (0, 50, 75 and 100 g) as main plot and bending angle (vertical, 0o, inclined, 45o and horizontal, 90o) as sub plot. Number of suckers, nodes, leaves and primary branches was established after 180 days. Number of suckers varied significantly (p≤0.05) across variety, bending angle and fertilizer levels, with the highest being recorded on KR4 (52.1), horizontally-bent plants (68.8) and mother bushes treated with 100 g of NPK (55.1). In addition, a significant (p≤0.05) interaction was also observed between the bending angle and fertilizer for all the three coffee varieties. Horizontally-bent coffee registered the highest number of suckers when applied with 100 g of NPK for KR1 (74.3) and KR3 (94.0) whereas, 75 g of NPK for KR4 (111.0). Our findings provide a guide to coffee nursery operators on best-bet good agronomic practices (GAP’s) for enhancing suckering of these CWD-r Robusta coffee varieties.