Plant Growth and Rhizosphere

Transcription

1 Plant Growth and Rhizosphere Kiyoshi Tsutsuki Root is a contact point between plant and soil What gives root to soil? What gives soil to plant through root? Root improves soil. Soil supports the growth of plant through the root. Ishiwari-zakura in Morioka, Iwate. Cherry root breaking the big stone. Soil factors related to crop production Natural conditions Crop production Root growth Human Nutrient environment Organic matter, Microbes, Nitrogen, Macro and micro elements Physical environment Soil animals, microbes Moisture, Air, Hardness, Soil temperature, Soil aggregates Soil environment History of earth and soil formation Fossil of stromalite First photosynthetic bacteria, producing oxygen. 89IIE 2I9E0E -I 7AC N.AI09I N 49E1C 4, 6BCACAP9AE3I9C49E 5IAA9AE94 N 0CAE9H9A9E9IAAI %N 0CAEI9CA4IAAEOEA %N 0CAE99C9 4 % N 0CAECAE9EIIIA9CI9EA 4 % 79II9E N 0CAE9ICOIIIA9CC9E 4 % 09ICOACI9AE N 0CAEIE9EO9 7ACI9AE % 0CAE9EBAE 19AE9AE 79I9IACI Bridged the change from the worlds of anaerobic to aerobic organisms. 1

2 Rhizoid and True root Seed plant Fern Moss plant Adventitious root Type of roots Various roots Dandelion Carrot Geranium Corn Grasses Vascular bundle Dahlia Cuscuta australis Vascular plant Moss plant Water hyacinth Ivy Orchid Root of protea and lupin Rows of Taxodium distichum (swamp cedar) in Saga University Cluster root Aerobic roots of swamp cedar Aerobic roots of aquatic trees Sarawak river, Malaysia 2

3 Forest Organic matter distribution Prairie Grasses Woods Annual dry matter production in root and above ground parts Plants Root (t/ha) Above (t/ha) Total (t/ha) Root/ Above barley wheat clover corn potato Sugar beet pine oak Tropical f German f Proportion of root to whole plant : Grasses Woods Root residue remained in soil after harvest : Some hundreds kg/10a, Some/ ha Root length Total root length / unit area Grasses km/m 2 Soy bean km/m 2 Potato 20 km/m 2 Total root length / unit mass Grasses km/m 3 Potato 100 km/m 3 Generally large in surface layer and decrease with depth. Large at cm depth for corns and soy bean. Factors influencing root development Crops with long growth period have longer roots. winter wheat Water shortage, high or low temperature, nutrients deficiency enhance the root growth. Shortage of sunshine retards the root growth. Maximum and frequent root depth of various crops. Plants Maximum (cm) Frequent (cm) Rice Winter wheat Spring wheat Barley Corn Soy bean Sugar beet Sweet potato

4 Maximum and frequent root depth of various crops. Plants Maximum (cm) Frequent (cm) Tomato Cabbage Cucumber Onion Asparagus6 th year Sunflower Alfalfa2 nd year Red clover Carbon supply 8 year Supply and storage of carbon to soil Humid tropics Tundra Desert 2 Grassland Temperate 06 Sub-boreal forest Temperate forest / Dry tropic forest Sub-boreal Humid tropic f. Agricultural land 4 Desert Tundra Carbon 5 storage Turn over rate of soil carbon in 3 climate zones. Climate zone England Temperate West Canada Cool temperate Brasil Tropics Soil types Luvisol Mollisol Spodosol Crop Wheat Wheat - fallow Sugar cane Soil weight (Mg/ha) Organic carbon (Mg/ha) Annual carbon input (Mg/ha) Turn over rate of C (years) Amino acid, organic acid, sugar Pectin, uronic acid, polysaccharide Cell membrane and wall Root cap, epidermal cells Soluble OM CO 2 Mucigel Fallen tissue Fallen cell Root zone Root Water P N O 2 K Trace elements Microbes Rhizosphere environment OM Microbial numbers ratio between rhizosphere and non rhisosphere Plants Wheat Oat Flax Timothy Alfalfa Red clover RhizoNon-rhizo Change in the root system of corn after the infection by microbes Infected root Aseptic root 4

5 Functions of rhizosphere microbes Decompose organic matter and hand nutrients to root. Protect root from disease germs. Symbiosis with mycorrhizal fungi enhance the absorption of hardly soluble phosphate and water far from root. Symbiosis with rhizobium bacteria enables nitrogen fixation. What root system does to soil : Formation of soil aggregate. Secretion of amino acid and sugar. Old root hair and root cap cell are fell. Stimulation of rhizosphere microbes Increase soil organic matter. What root system does to soil : 2 Solubilize hardly soluble nutrients such as phosphates in Ca, Fe and Al salt form. Mugineic acid for wheat. Piscidic acid for pegion pea. Oxalic acid, citric acid, malic acid are very common in various plants. Secretion of organic acids from root Lupin Citric acid Ca phosphate Alfalfa Citric acid Ca phosphate Rapeseed Pigeon pea Chick pea Malic acid and citric acid Piscidic, malonic, oxalic acids Citric acid and succinic acid Ca phosphate Fe phosphate Ca phosphate Fe phosphate Buckwheat Brassica napus Hydrogen ion Ca phosphate Chickpea Pigeonpea The bean adapted to Vertisol in India. Grow well on high ph, high Ca, and dry soil. Secretes citric acid. The bean adapted to red soil (Alfisol) in southern India. Absorbs iron phosphate. Secretes piscidic acid. 5

6 Root nodules of alfalfa Sugar Sugar Large VA mycorrhiza Rhizobium Medium Small Mycorrhiza in the root of timothy Ectomycorrhiza Gymnosperm Pinaceae, Cupressaceae Angiosperm Fagaceae, Ulmaceae, Dipterocarpa ceae, Betulaceae, Aceraceae, Salicaceae, Rosaceae, Tiliaceae, etc. 0.1 mm Beech root coated by exo-arbuscular fungi VA mycorrhiza Arbuscular Vesicular 6

7 endo-type arbuscular fungi in orchid What is VA mycorrhiza? Symbiotic microbes with plant root. Symbiotic relationships between VA and plants Absorption of phosphate and water in plants is promoted by VA. Hyphae in soil Living hyphae invaded in a cell Digested hyphae VA accepts photosynthetic products from plant. Effect of mycorrhizal formation on the plant growth. Above ground growth of plants Plants with mycorrhiza Plants without mycorrhiza Level of available phosphate in soil Effect of mycorrhizal inoculation on the growth of leek. No inoculation Inoculated Effect of mycorrhizal inoculation on the growth of leek. Available phosphate (mg/100g) in horizontal axis. Relationship between soil hardness and root elongation Physical properties of soil influencing the root growth Relative root elongation soil hardness Cited from the homepage of Prof. Hatano, Hokkaido University Penetration resistance value Inverse proportion Moisture content Air space volume Inverse proportion Direct proportion Bulk density Optimum range around 1.0 7

8 Comparison of root sections between barley and rice Non rhizosphere soils in upland and paddy fields Redox state Major microbes States of various substances Upland Oxidative Aerobic microbes NO 3-, Fe 3+, MnO 2, SO 4 2- Paddy Reductiv e Anaerobic microbes NH 4 +, Fe 2+, Mn 2+, S 2- Barley Rice Upland Paddy Rhizosphere soils in upland and paddy fields Nitrogen absorption Nitrate absorbtion CO 2 secretion + NH 4 absorbtion H + secretion ph Increase compared with non rhizosphere Decrease compared with non rhizosphere Redox state Decrease compared with non rhizosphere Increase compared with non rhizosphere What is good soil for the root growth? Root can develop deep, wide, and healthy, and can supply enough amounts of nutrient and water to above ground part. For this purpose What is good soil for the root growth? Good soil aeration, drainage, and water retention, and soft. What is good soil for the root growth? Have a good balance in nutrients. Have a proper ph value. Aggregate structure formation Application of organic matter Soil diagnosis is carried out. Improvement of soil acidity Application of lime 8

9 What is good soil for the root growth? Contains organic matter, food for soil microbes and organisms. Soil organisms are abundant. Application of compost and green manure. 9