Genetic variation in phosphorus efficiency traits in tropical maize in low p soils

Low available phosphorus (P) still remains a major limitation to maize (Zea mays L.) productivity in low P soils. The objectives of this study were to (i) determine the extent of genetic variation in P efficiency among selected Kenyan maize under low P soils (ii) select P efficient maize experimental hybrids. A total of 32 experimental hybrids were evaluated for variation in tolerance to low P at high P (36kgP/ha) and low P (6kgP/ha) conditions across four locations using split plot arrangement in RCBD replicated three times. Mean grain yield was significantly lower (2.49 t/ha) across the low P treatment compared to the high P treatments (4.78 t/ha). Relative yield reduction was comparable across the four locations except at Sega where it was a little higher (59.4%). A 48.9% mean yield reduction was observed at the low P treatment compared with the high P treatment across the locations. Eighteen out of the 32 experimental hybrids exhibited Agronomic Efficiency (AE) above the locational mean > 44.8 kgkg-1 P. Mean phosphorus efficiency ratio (PER) of 546.7 kgkg-1 P was obtained across the four locations with Migori exhibiting the highest mean (556.5 kgkg P-1). Majority of the experimental hybrids (57%) had higher phosphorus acquisition efficiency (PAE) than the average of all the genotypes. A mean phosphorus efficiency (PE) of 71.6 % was recorded across the locations. In most cases, genotypes showing higher P efficiency traits (PE, PAE, PUE, AE, PER) had higher grain yield production under low P supply. The genetic variation observed among the maize genotypes demonstrates the potential for maize improvement which will facilitate efficient acquisition and utilization of the limited Pi fertilizers.