Intro to Crop Science

Fibrous roots

Many small roots, example: grasses.

Tap roots

One larger root with smaller roots coming off of it, example: carrots.

Node

Part of attachment to the leaf.

Bud

Underdeveloped and elongated stem.

Terminal bud

Tip of the stem.

Internode

Part of the stem between nodes.

Lenticels

Cells on the epidermis.

Modified stems

Stems that do not always grow upright or vertically.

Crowns

Compressed stem.

Stolons

Stem that grows horizontally above ground.

Spurs

Found on branches of woody plants; growth has been severely restricted.

Rhizomes

Underground horizontally growing stems.

Corms

Underground structures that are compressed and thickened stems.

Bulbs

Compressed stem; prominent part is the stem with modified leaves.

Tubers

Underground stems that are highly enlarged.

Vascular bundles

Structures that run the length of a plant’s stem, transporting nutrients.

Photosynthesis

The process by which green plants convert light energy into chemical energy.

Chlorophyll a

Primary photosynthetic pigment in plants, absorbs mainly blue and red light.

Chlorophyll b and Carotenoids

Additional pigments that aid in light capture and reflect other wavelengths.

Chloroplasts

Organelles where photosynthesis occurs.

Thylakoid

Membranous sacs in chloroplasts where light reactions occur.

Granum

A stack of thylakoids.

Stroma

Fluid-filled space in chloroplasts where the Calvin cycle occurs.

Stomata

Pores that regulate gas exchange in plants.

Mesophyll cells

Cells in leaves containing chloroplasts, responsible for photosynthesis.

Light Reactions

The first stage of photosynthesis that occurs in the thylakoid membranes.

Calvin Cycle

The second stage of photosynthesis occurring in the stroma, producing glucose.

C3 Plants

Plants that use the normal photosynthesis pathway.

C4 Plants

Plants that adapt to dry conditions by fixing CO2 into a four-carbon compound.

CAM Plants

Plants that collect CO2 at night and run the Calvin cycle during the day.

ATP

Energy currency of the cell, produced during photosynthesis.

NADPH

Electron carrier that provides reducing power for the Calvin cycle.

Transpiration

Loss of water from plants in the form of water vapor.

Heat of Vaporization

The energy required to convert water from liquid to gas.

Cuticular Transpiration

Loss of water through the epidermis covered by a cuticle.

Lenticular Transpiration

Water vapor loss through pores in the outer layer of woody plant stems.

Stomatal Transpiration

Water vapor loss through the stomata.

Guttation

Water released by plants in liquid form through hydathodes.

Evaporation

The process by which water changes from a liquid to a vapor.

Diffusion

Movement of water vapor from higher to lower concentration.

Apoplastic Route

Water movement through non-living parts, such as cell walls.

Symplastic Pathway

Water movement through living plant cell connections called plasmodesmata.

Transmembrane Pathway

Water movement across cell membranes.

Transpiration-cohesion-adhesion theory

Explains how water moves from roots to leaves.

Factors Affecting Transpiration

Factors include leaf number, stomatal position, cuticle thickness, light, temperature, humidity, wind, and water availability.

Perfect Flowers

Flowers that possess both male and female reproductive organs.

Examples of Perfect Flowers

Roses, lilies, peas, and beans.

The Calvin cycle is the

second stage of photosynthesis

the calvin cycle happens in the

stroma

the calvin cycle produces

glucose (sugar)