Relation of Cotton Growth and Yield to Minimum Leaf Water Potential1
- D. W. Grimes and
- H. Yamada2
Field studies were conducted over a 3 year period in the San Joaquin Valley of California to define the associations between minimum or midday leaf water potential (ψ1)and cotton (Gossypium hirsutum L.) growth parameters, mainstem elongation and fiber growth, and to evaluate the suitability of using minimum (ψ1) as an index for irrigation scheduling. Locations on two soils, differing widely in water retention and transmission properties, were maintained for two of the test years.
Mainstem elongation (EL) was greatest after stress was alleviated by irrigation. EL (cm/day) was reduced linearly as minimum (ψ1) (bars) declined; the function EL = 5.08 + 0.200(ψ1) was derived from available observations. Mainstem elongation essentially stopped when minimum (ψ1) dropped to −24 bars. Fiber growth (elongation and weight increase) proceeded unchecked until (ψ1)reached -27 to -28 bars, when the growth rate decreased markedly, indicating that fiber growth is probably a preferred sink at high stress levels.
Minimum (ψ1)declined linearly with time following irrigation. High yields were obtained when minimum (ψ1)was allowed to decline to about -19 bars before irrigating. Any response resulting from differential conditioning, from prior water stress, was not sufficient to detract from the usefulness of minimum (ψ1) as an index for scheduling irrigation.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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