Crop Growth and Development Flashcards

Growing degree days (GDD) are calculated using which formula?

Answer: (Max temp + Min temp) / 2 - Base temp

GDD = ((Tmax + Tmin) / 2) - Tbase, accumulating thermal time above a crop-specific base temperature.

What is the term for the water lost from the soil-plant system through both evaporation and plant transpiration?

Answer: Evapotranspiration

Evapotranspiration (ET) combines soil evaporation and plant transpiration and is a key measure for irrigation scheduling.

The Feekes scale is a growth staging system used for which crop?

Answer: Small grains (wheat, barley, oats)

The Feekes scale is a widely used system for staging small grain crops like wheat and barley from emergence through grain maturity.

Which process describes the movement of photosynthetically fixed carbon from leaves to other plant organs through the phloem?

Answer: Mass flow (pressure-flow hypothesis)

The pressure-flow hypothesis explains phloem transport: high sugar concentration at sources creates pressure that drives flow toward sinks.

In cotton, the NAWF (Nodes Above White Flower) index is used to determine:

Answer: Cutout stage and timing for irrigation termination

NAWF declines as the season progresses; a NAWF of 5 indicates cutout, when new fruiting positions are no longer being set.

What is the physiological maturity stage in corn indicated by the formation of?

Answer: Black layer at the kernel base

Black layer formation at the base of the kernel marks physiological maturity in corn, when maximum dry matter accumulation has occurred.

Which nutrient deficiency typically causes interveinal chlorosis in the young, newly emerging leaves of a crop?

Answer: Iron (Fe) deficiency

Iron deficiency causes interveinal chlorosis in young leaves because Fe is immobile in the plant and cannot be remobilized from older tissues.