Critical Petiole Nitrate‐Nitrogen for Lint Yield and Enhanced Maturity in Pima Cotton

Abstract

Petiole NO3‐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.

Monitoring nitrogen nutrition in cotton

“…Petiole N-NO 3 -concentrations as high as 24-30 g kg -1 have been reported in upland cotton (Maples et al, 1977;Gardner & Tucker, 1967), but a critical minimum level of 1-2 g kg -1 during the first flower period was suggested to ensure growth and yield of upland cotton in California (MacKenzie et al, 1963). In Texas, this level was adequate for maximum production of Pima cotton, depending on the season (Tewolde et al, 1995).…”

Fate of Nitrogen‐15 Applied to Irrigated Acala and Pima Cotton

“…In addition, no data are available for Pima, an extra‐long staple cotton that generally yields less than Upland cotton (Unruh and Silvertooth, 1996). Compared with Upland cotton, Pima is more sensitive to delayed planting and excessive N fertility and has a more pronounced indeterminate growth habit, which limits production to regions with long growing seasons (Tewolde et al, 1995; Kittock et al, 1981, Silvertooth et al, 1995). This research was conducted as a complement to a 5‐yr, multilocation re‐evaluation of N fertilizer management guidelines for Acala cotton production in the San Joaquin Valley (Hutmacher et al, 2004).…”

Response of Irrigated Acala and Pima Cotton to Nitrogen Fertilization

“…Although similar in many respects, Pima differs from Upland cotton in others. Pima is more sensitive to delays in planting and excessive N fertility, which can result in greater vegetative growth and delayed maturity (Tewolde et al, 1995; Kittock et al, 1981; Silvertooth et al, 1995). Because most of the cotton grown in the USA is G. hirsutum [98.9% in 2000 (USDA Econ.…”