Plant Adaptations to Nutrients & Water: Thriving in Deficient & Arid Environments, Study notes of Agricultural engineering

Download Plant Adaptations to Nutrients & Water: Thriving in Deficient & Arid Environments and more Study notes Agricultural engineering in PDF only on Docsity! Plant adaptations to their physical environment LAND/ SOCR 220 Plant adaptations to nutrients A. Plants with high nutrient demand will do poorly in nutrient depleted soils B Plants with lower demand will grow. more slowly and survive in nutrient poor systems. The “big guys”: N P K S Ca & Mg , , , , , • N: obtained from atmosphere; energy intensive; ~½ plant needs met by fixation • P: mainly insoluble low supply , • K: primary minerals (micas), leached easily • S: fairly insoluble, requires special microbes, reduces pH • Ca, Mg: easily leached More Plant adaptations to nutrients • A. Longer lived leaves in nutrient poor systems B Greater production of roots but C is• . allocated to roots at expense of leaves… Importance of the Phenotype • Phenotype = genes + environment + (gene-environment interaction) • Natural selection has favored organisms that can modify their phenotype to be appropriate for different conditions within the species range Thi difi ti i k h t i• s mo ca on s nown as p eno yp c plasticity Soil water • Smaller soil grains = greater surface area • Matrix potential: strength of forces holding water to the soil particles • Units of pressure (atmospheres): more negative values attract water Transpiration & water uptake • Water potential of dry air: -1332 atm @ 20°C • Vascular plants move water long internal distances T i h i th• ens on-co es on eory Tension-cohesion theory • The force required to move water within xylem elements is generated when water moves from the vascular vessels to leaf cells, replacing transpiration losses • water is literally pulled from the roots to the stomates Plant nutrient uptake • Nutrients typically more dilute in environment than in the plant • Active transport across root membrane • Symbiosis with fungi • Often limited by root surface area, so alter root:shoot ratio Terrestrial organisms deal with salt blpro ems • Transpiration loss of water leads to salt accumulation in all leaves