Effects of multi-growth stage water deficit and orthosilicic acid fertiliser on lodging resistance of rice cultivars

Abstract

Lodging and water deficit (WD) are both yield limiting factors for rice production in Africa. A number of New Rice for Africa (NERICA) cultivars with drought adaptive and high yielding ability have been released but the extent of their lodging susceptibility due to water deficit is unclear. Application of orthosilicic acid (OSA) fertiliser can reduce lodging due to water deficit. An experiment was therefore conducted involving six cultivars (NERICAs 1, 4, 6, 7, 8 and Moroberekan), subjected to five multi-growth stage WD treatments: non-stressed (Nst), 10-day stress at each of any two stages of vegetative (Veg), reproductive (Rep) and grain filling (Grain) stages viz (Veg10 + Rep10), (Veg10 + Grain10), (Rep10 + Grain10), and 7-day stress at each stage (Veg7 + Rep7 + Grain7) and with/without 500 mL ha−1 of OSA fertiliser. Lodging traits (LTs) such as lumen diameter, bending moment, panicle weight (PW) and grain yield (GY) were increased by OSA fertiliser. Under Veg7 + Rep7 + Grain7 stress, OSA fertiliser increased rice vigour through increases in internode length, lumen diameters and cross-section modulus by 7%, 18% and 18%, respectively, while under Veg10 + Rep10 stress, culm wall thickness was increased by 20%. Veg10 + Rep10 stress caused the most significant reduction in all LTs but with lowest lodging index (LI, 0.32) attributed to reduced PW and GY. Among the cultivars, Moroberekan combined higher GY with average LI (0.40) across the stress conditions while NERICA 1 had the lowest LI (0.34) attributed mainly to its short height. Although water deficit caused a reduction in lodging resistant traits, resistance to lodging under Veg10 + Rep10 and Veg7 + Rep7 + Grain7 stresses can be enhanced with OSA fertiliser.