식물생리학
Highlights of plant evolution ( 식물 진화의 하이라이트 ). This diagram reflects a hypothesis about the general relationships between plant groups. The broken lines indicate that the phylogeny of bryophytes is uncertain. 육상식물 선태식물 ( 비관다발식물 ) 관다발식물 종자식물 비종자 관다발식물 차축조류태류 각태류 선류 석송식물 양치식물 겉씨식물속씨식물 종자식물의 기원 ( 약 3 억 6 천만 년 전 ) 관다발식물의 기원 ( 약 4 억 2 천만 년 전 ) 육상식물의 기원 ( 약 4 억 5 천 5 백만 년 전 ) 조상 녹조류
Net flow in whole plants
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transpirational pull flow from greater to lower water concentration relies on cohesion & adhesion of water –cavitation breaks chain of water molecules Ascent of xylem sap
Figure Water-conducting cells of xylem
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The availability of soil water and minerals Long-distance transport of water from roots to leaves
Phloem transport pressure flow 1high sugar concentration at “source” 2sugar diluted with water from xylem creating pressure for flow 3sugar unloaded at “sink” where it is metabolized or converted to starch 4excess water flows to xylem back to “source” translocation: movement of food from “source” to “sink(s)” Pressure flow in a sieve tube
Some “hot” areas in plant water and nutrient research Improving plant water-use efficiency Improving salt tolerance Improving nutritional value of plants (e.g., golden rice, increasing Fe content) Phytoremediation
Life on Earth depends on flow of energy from sun
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Fig. 8.14
Fig. 9.19