Effect of long-term nutrient management on root chemical properties and morphology, grain yield and phosphorus use efficiency of wheat under sorghum-wheat sequence

Abstract

A permanent long-term fertilizer experiment (AICRP-LTFE) has been continuing since 1988–89 at Research Farm, Department of Soil Science and Agricultural Chemistry, Akola, Maharashtra. Field and pot experiments were conducted during rabi season of 2016–17 (29th cycle) at Akola in this LTFE. The experimental design of the field experiment was randomized block design and in the case of the pot experiment it was completely randomized design. Pot culture experiment was conducted to assess the root length and root volume by using automated root analyzed systems, whereas, field experiment were conducted to study the root chemical properties. There were 12 treatments replicated three times in the field and pot experiments. The treatments comprised of different levels of recommended dose of fertilizers (RDF) viz., 50, 75, 100 and 150% and RDF in combination with farmyard manure (FYM), FYM alone (5 t ha−1), RDF devoid of S, RDF along with S @ 37.5 kg ha−1 and Zn @ 2.5 kg ha−1, NP, N alone and control. The results indicated that application of 100% NPK + FYM significantly improved the root length of wheat at 30, 60 and 90 days after sowing (DAS). The root volume increased to the tune of 0.098, 0.107 and 0.119 cm3, respectively at 30, 60 and 90 DAS in the treatment of 100% NPK + FYM. The application of 100% NPK along with S registered higher activity of root acid phosphatase at 30 DAS (235 μm PNP g−1 fresh weight h−1) and 60 DAS (275 μm PNP g−1 fresh weight h−1). The higher root CEC i.e. 19.1 cmol(p+)kg−1 was registered with the application of 100% NPK + FYM at 30 DAS and 23.8 cmol(p+)kg−1 at 60 DAS. The application of 100% NPK + FYM @ 5 t ha−1 recorded significantly higher value of root oxidase activity viz. 755 and 845 mg α-NA g−1 fresh weight h−1 at 30 and 60 DAS, respectively. The grain yield of wheat was influenced significantly with the application of 100% NPK + FYM @ 5 t ha−1 (34.0 q ha−1). The higher P use efficiency (28.9%) was registered under integrated use of chemical fertilizer and organic manures. The P use efficiency was significantly correlated with root acid phosphatase activity at 30 DAS (r2 = 0.417**) and 60 DAS (r2 = 0.595**).