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Critical Petiole Nitrate‐Nitrogen for Lint Yield and Enhanced Maturity in Pima Cotton
Author(s) -
Tewolde Haile,
Fernandez Carlos J.,
Foss D. C.,
Unruh Larry G.
Publication year - 1995
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj1995.00021962008700020014x
Subject(s) - lint , malvaceae , petiole (insect anatomy) , fiber crop , agronomy , yield (engineering) , gossypium barbadense , zoology , maturity (psychological) , biology , horticulture , gossypium hirsutum , botany , psychology , hymenoptera , developmental psychology , materials science , metallurgy
Petiole NO 3 ‐N concentration (PNN) has been recommended as an indicator of midseason N deficiency in upland cotton ( Gossypium hirsutum L.). Its use in Pima cotton ( G. barbadense L.) management, exspecially when early maturity is the goal, is not well documented. A 3‐yr study evaluated PNN as an indicator of N status in Pima cotton in order to identify a critical minimum PNN level for yield and early maturity. Treatments were five preplant applied N rates of 0 to 180 kg ha −1 in 1990 and 0 to 269 kg ha −1 in 1991 and 1992. The PNN was measured throughout boll development, starting ≈ 2 wk before or at first flower. Applied N significantly ( P ≤ 0.05) affected PNN in 1991 and 1992, when residual soil N was low, but not in 1990, when residual N was high; differences among treatments in 1991 and 1992 were largest during early flowering. PNN was a good indicator of plant N status within but not across seasons. Based on early‐flowering samples, the critical PNN level for lint yield was 3.84 g kg −1 in 1991 and only 1.75 g kg −1 in 1992; in 1990, residual soil N alone resulted in PNN much higher than the critical levels in the other years. PNN < 2 g kg −1 in 1991 and < 1 g kg −1 in 1992 resulted in earlier maturity, but also resulted in less lint yield. Pima cotton PNN did not exceed an average of 11 g kg −1 , in contrast to 24 to 30 g kg −1 reported for upland cotton. Plant growth or petiole anatomical variables that cause year‐to‐year variation in PNN should be identified and the necessary normalization made before PNN can be used as a midseason diagnostic tool in Pima cotton.