Arbuscular Mycorrhizal Fungi and Silicon Effects on Nutrient Uptake, Growth and Yield of Sorghum under Water Stress in Machakos County, Kenya
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Date
2021
Authors
Gacheri, Kaaria Kallen
Journal Title
Journal ISSN
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Publisher
Kenyatta University
Abstract
Sorghum (Sorghum bicolour L. Moench) is an important cereal crop ranked second after maize as a food security in Kenya. However, its production is threatened by low soil fertility and moisture content. Many studies on arbuscular mycorrhizal fungi (AMF) have shown its importance in nutrient and water uptake, resulting in better yields of crops. In addition, silicon helps in plant resistance to both abiotic and biotic stresses. The study evaluated effects of AMF and silicon on nutrients uptake, growth and yield of two sorghum varieties under different water regimes. Two field experiments were carried out in Machakos County, Kenya. A Randomized Completely Block Design (RCBD) in a factorial arrangement was used to lay out the experiment. The factors tested included: Two levels of sorghum varieties (Seredo and Machakos local red), the other factor was water regimes in three levels (20, 40 and 60%) while the third level was silicon and Mychorriza (plus and minus). Sorghum varieties and leek were used as trap plants in a greenhouse experiment. Data collection was done on sorghum growth, yield and nutrient uptake, AMF colonization percentage and AMF diversity. Analysis of variance (ANOVA) was used to analyze data using R software and significant means
se parated using Tukey’s test at 5% significance level. The results showed that Seredo variety had the highest shoot dry weight (107 g), longest roots (44.1 cm) and longest period to 50% flowering (76.4%) while Machakos local red had tallest plants (210.9 cm) and highest number of leaves (10.8). At 60% water regime, Si amendment and AMF inoculation enhanced sorghum growth better than other treatments. Seredo variety recorded the highest grain yield (4.4 tha-1). The variety also revealed various nutrient uptake as follows:- phosphorus (111.1 kg ha-1), nitrogen (34.7 kg ha-1), K (69.7 kg ha-1), calcium (3296 kg ha-1) and magnesium (172.1 kg ha-1) uptake. It has recorded the best AMF root colonization. Moreover, Seredo variety had the maximum harvest index of 0.39. At 40% water regime, Seredo variety amendment with Si and AMF produced the highest grain yields, nutrients uptake and AMF root colonization. A total of 4 AMF genera (Gigaspora, Scutellospora, Acuolospora and Glomus spp) from the family Gigasporaceae, Acaulosporacea and Glomeraceae were detected from both trap culture and experimental soil. The trap culture had the highest number of spore density 57.5 (leek), 32.8 (Seredo) and 23.5 (Machakos red local) compared to the experimental soil that had 15 spores per 100g of soil. Leek plants trapped more Glomus (23), Scutellospora (15.8) and Acaulospora (11.8) than both sorghum varieties but Seredo variety trapped most Gigaspora (15.3) per 100g of soil. This study demonstrated that Si amendment and AMF inoculants have potential of improving sorghum growth and yield under water stressed conditions as indicated by the high grain yield and nutrients uptake achieved at 40% water regime. Therefore, combined use of Silicon and AMF is recommended for improving sorghum productivity in water stress areas. Such strategies could enable food production in marginal areas characterized by low rainfall and high temperatures.
Description
A Thesis Submitted in Partial Fulfillment of the Requirements for the Award of the Degree of Master of Science in Agronomy, In the School of Agriculture and Enterprise Development of Kenyatta University, October, 2021
Keywords
Arbuscular Mycorrhizal Fungi, Silicon Effects, Nutrient Uptake, Growth, Yield of Sorghum, under Water Stress, Machakos County, Kenya