PRODUCTIVITY AND GRAIN QUALITY OF BREAD WHEAT (TRITICUM AESTIVUM l.) GENOTYPES AS INFLUENCED BY LLME, MINERAL FERTILIZERS, AND VERMICOMPOST ON ACID SOILS OF GUTO-GIDA AND WELMERA DISTRCICTS, OROMIA REGION, ETHIOPIA

Abstract

Bread wheat is one of the major crops cultivated in the western regions of Ethiopia. However soil acidity with a pH < 5.5 is affecting production of bread wheat. Thus, the use of acid tolerant wheat genotypes is cost effective and environmentally friend practice of producing crops. Therefore, soil-lime incubation was conducted in 2020 at Nekemete Soil Research Center for a period of 42 days to determine actual lime rate required for optimizing the soil pH (6.0 – 6.5) using 15 rates of lime (CaCO3), namely 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13 and 14 t ha–1. The experiment was arranged in CRD and each treatment was replicated four times. Soil-based screening of P-efficient wheat genotypes was conducted at Nekemte Soil Research Center during the last three months of 2020 to screen and identify P-efficient bread wheat genotypes on strongly acidic soil using 49 bread wheat genotypes. The experiment was arranged in RCD and replicated two times. Field evaluation of P-efficient wheat genotypes for their acid soil tolerance was conducted in Guto-Gida district in 2021 to evaluate P efficient bread wheat genotypes under natural condition using six bread wheat genotypes (4 P-efficient and 2 P-inefficient). The experiemt was arranged in RCBD and replicated two times per treatment.Assessing yield and grain quality of P-efficient wheat genotypes on acidic soil was conducted in Wolmera district in 2022 to assess yield and grain quality advantages of P efficient genotype using two wheat genotypes (one P-efficient and one P-inefficient) under integrated application of three P rates (0, 30 and 60 ha–1), two lime rate (0 and 2.1 t ha–1) and two VC rate (0 and 2 t ha–1). The experiment was arranged in RCBD and each treatment was replicated two times; and soil chemical propertie, on yield components and yield and grain quality responses of wheat was assessed under three P rates (0, 20 and 40 kg P ha–1), three sulfur rate (0, 15 and 30 kg S ha–1) and three VC rate (0, 2 and 4 t ha–1) at Guto-Gida district in 2019 and 2020. The experiment was arranged in RCBD and each treatment was replicated three times. The result of soil-lime incubation study revealed that the actual amount of lime xix required to raise soil pH to optimum range (6.0 – 6.5) for wheat production while dropping %Al saturation below critical value (10%) was 8 t ha–1. At this lime rate the target soil pH and Al concentration values were 6.23 and 9.97%, respectively. At this target pH value, compared to the control, soil exch. acidity (cmol(+) kg–1) and Al concentration (%) were decreased by 1.36 and 17.66 units, respectively. On the other hand, soil available P (mg kg–1), exchangeable basic cations, namely, Ca, Mg and K (cmol (+) kg–)1 increased by 9.75, 3.8, 1.07 and 0.08 units, respectively. The results of screening P-efficient bread wheat genotypes revealed that the highest shoot height (43.36 cm) and shoot dry weight (523.68 mg) were recorded for genotypes 17(P-efficient) when treated at 60 kg P ha–1 while the lowest shoot height (18.72 cm) and the lowest shoot dry weigth (145.28 mg) was recorded for genotype 32 (P-inefficient) under control. The superior value of root dry weight (62.73 mg) was recorded for genotypes 28 (P-efficient) while the lowest (19.07 mg) was recorded for genotype 32. Based on values of grain yield efficiency index (GYEI) 10 genotypes (20.42%) were grouped as P efficient (GYEI ≥ 1.0) and considered as acid tolerant, 13 (26.53%) of them were medium (GYEI 0.5–1.0) while the rest 26 (53.06%) were grouped as P inefficient (GYEI < 0.5) and sensitive to acidic soil. The results of field evaluation study of P-efficient wheat genotypes revealed that genotype 17 gave superior values in grain yield (4.323 t ha–1) and in number of grains per spike (47.34) at 40 kg P ha–1supply (which were at par with no lime and limed) while the lowest values in grain yield (0.613 t ha–1) and in number of grains per spike (11.72) were recorded for genotype 32 under control plot (which were at par with genotype 48 under control). The results of grain yield and quality assssement of P-efficient wheat genotypes revealed that the highest grain yield (5.145 t ha–1) was recorded for P-efficient genotype 17 at 60 kg P ha–1 supply which was at par with 30 kg P while the lowest (1.3763 t ha–1) was recorded for P-inefficient genotype 32 under control plot. The results of yield and grain quality variabes of P-efficient wheat genotypes revealed that the highest values in grain N (2.18%), protein (13.31%) and wet gluten (36.77%) were obtained at 2 t VC*2.1 t L*60 kg P ha–1 while the lowest values in grain N (1.49%), protein (9.31%) and wet gluten (21.67%) were recorded under the control plot. The highest value of grain N and protein contents were recorded for genotype 32 treated at 60 kg P while the lowest values were recorded for the same variety under its control plot. The economic analysis revealed that the maximum net benefit of 264683.30 ETB ha–1 with MRR 811.17% was obtained at 60P*2.1 t lime ha–1 for P-efficient genotype 17. The results of xx phosphorus, sulfur and VC application study on post-harvest soil chemical properties revealed that application of 4 t VC increased soil pH from 5.33 to 5.82 (9.23%) which shifted from strongly acidic to moderately acidic while reducing soil exchangeable acidity from 1.35 to 0.95 (42.11%) compared to control. Application of 40 kg P*4 t VC*0 kg S markedly increased soil available P by 67.22% that shifted from very low to medium category. Combined application of 0 kg P*30 kg S*4 t VC increased soil S by 314.29% that shifted from very low to medium category. Applications of 0 kg P*S 30 kg S* 4 t VC changed soil CEC and exch. Ca from medium to high category. Similarly, combined application of 40P*30 S*4 t VC resulted in 657.49%, 857.09% and 223.99% increments for number of grains per spike, grain yield and straw yield, respectively over control plot. The highest values of grain N (1.83%), crude protein (11.39%) and wet gluten (33.32%) were recorded at 40P*30S*4tVC combination while the lowest values in of grain N (1.28%), crude protein (7.93%) and wet gluten (17.01%) under control plot. Combined application of 40 kg P*30kg S*0 t VC resulted in straw N, grain and straw P, grain and straw S increments by 105.88%, 79.17 and 183.33%, 222.22 and 65.63%, respectively. The economic analysis showed that maximum net benefit 103,283.2 ETB ha-1 with MRR of 732.78% was obtained from 40P*15S kg ha–1. In general, P-efficient wheat genotypes perform superion in yield components and yield and grain quality, and provide maximum net farm benefit under integrated application of organic and inorganic fertilizers. Thus, use of acid tolerant P- efficient bread wheat genotypes is an alternative method for sustainable and economically viable wheat production on acidic soils of the study area.