Influence of Arbuscular Mycorrhizae Strains on Phosphorous Nutrition, Rooting, and Growth of Tea (Camellia Sinensis) Clones
Phosphorus is a critical nutrient for plant growth and makes up about 0.2% of dry matter by weight. In soil, phosphates may be present in relatively large amounts, but much of it is often made unavailable because of its very low solubility due to its complexes with iron, aluminum, and calcium, resulting in very low concentrations (10 μm or less) in the soil solution. Tea roots alone may be incapable of taking up phosphate ions that are demineralized in soils with a basic pH. Mycelia of mycorrhizal fungus can, however, access these phosphorus sources, and make them available to the plants they colonize. Mycorrhizal fungi form relationships with over 95% of plant species. This therefore formed the basis for the current study which determined the effect of different mycorrhizal strains on infection rates, root initiation and establishment, phosphorus uptake, shoot growth parameters in seedlings of different tea clones, treated with different Mycorrhizal strains. In addition, the chemical and physical property changes in soils treated with different mycorrhizal fungal strains was determined. The study was laid out in a Randomized Complete Block Design (RCBD) with factorial arrangements. The phosphorus treatment was a standard rate in all the plots while two clones of tea (S15/10 and SC 12/28), and three mycorrhizal treatments (0 Kg/ha, 50 Kg/ha and 70 Kg/ha). The treatments were then replicated three times. Data were collected on initial time of callusing, length of time for roots to start growing, chlorophyll content, percentage success of shoot formation, length of roots, infection percentage of Mycorrhizae, root biomass, soil phosphorus content, plant tissue phosphorus, and root infection by mycorrhizal fungus (%). Application of mycorrhizae strains improved the chlorophyll content in both tea clones with clone S 15/10 being the highest (489.8) at 50 kg Mycorrhizae ha-1 rate, while the highest callusing rate (73.3%) was also observed on the same treatment. Significant differences (P≤0.05) were observed on the growth parameters with the highest recorded under clone SC 12/28 where mycorrhizae strains were incorporated. The soil pH was positively influenced by reducing the acidity content significantly where mycorrhizae strains were introduced with the highest unit change (1.3) being recorded on clone SC 12/28 at the 50 kg Mycorrhizae ha-1 rate. The same treatment also significantly increased the soil total phosphorus level (2.3 g/kg) compared to all other treatments with the least change observed on the control. The introduction of mycorrhizae strains significantly increased the abundance of other already existing mycorrhizae fungi population indicating a positive co-existence. The intensity of AMF colonization in the root fragments was highest (86.7%) under clone SC 15/10 at the rate of 50 kg Mycorrhizae ha-1 while the highest Arbuscule abundance in mycorrhizal parts of root fragments (85.9%) was observed at the 70 kg Mycorrhizae ha-1 rate on clone SC 15/10 with clone SC 12/28 at the rate of 50 kg Mycorrhizae ha-1 having 83.8%. The results show that mycorrhizal inoculation combined with phosphorus application clearly reinforces growth, mineral content, and the chlorophyll content.