Nitrogen Assimilation and Growth of Cotton Seedlings under NaCl Salinity and in Response to Urea Application with NBPT and DCD

Abstract

Salinity stress and inefficient nitrogen fertilization adversely affect cotton growth and yield. The effect of salinity on the growth and stress response of cotton seedlings and the effect on N‐use efficiency from the use of the inhibitors of urease (NBPT) and nitrification (DCD) under salinity stress were studied in growth chambers. The study consisted of three levels of salinity – low (0.45 dS m−1), moderate (8 dS m−1) and high (16 dS m−1) – and five N treatments – unfertilized control, 100 % N rate with urea, 80 % N rate with urea, 80 % N rate with urea +NBPT and 80 % N rate with urea +NBPT + DCD. The results indicated that salinity stress reduced plant growth (low leaf area and plant dry matter), decreased N assimilation (low NR, GS and protein), increased plant stress response (high GR and SOD), and decreased leaf chlorophyll, stomatal conductance and quantum yield. Addition of NBPT to urea improved N uptake by 22 % under low salinity; however, this effect was not observed with increasing salinity. No benefit of addition of DCD was observed in any of the parameters collected. In conclusion, salinity stress hindered the performance of the additive NBPT and negatively affected the growth and physiology of cotton.

Screening and evaluation of reliable traits of upland cotton (Gossypium hirsutum L.) genotypes for salt tolerance at the seedling growth stage

“…Similar findings were reported in salt-stressed cotton genotypes, e.g., the salt-tolerant genotype CCRI-79 maintained the maximum photosynthetic rate compared with the salt-sensitive genotype Simian-3 (hang et al 2014). The gsw also decreased under salt treatment (Kawakami et al 2013) and a significant decrease was also observed in the present study. The possible mechanism of gsw reduction under salt stress may be the increase of abscisic acid levels (He and Cramer 1996) and/ or the decrease of stomatal aperture (Ahmed et al 2013).…”

Impact of salt stress on photosystem II efficiency and antioxidant enzyme activities of safflower (Carthamus tinctorius L.) cultivars

“…The decrease in chlorophyll contents might be related to an increase of chlorophyll degradation or a decrease of chlorophyll synthesis (Santos, 2004). It was also reported that, under saline conditions, chlorophyll content declined in soy bean (Çiçek and Çakırlar, 2008), sugarcane (Cha-um and Kirdmanee, 2009), and cotton (Kawakami et al, 2013). As with chlorophyll content, carotenoid amounts reduced in relation to salt treatments ( Figure 3B).…”

Nutrición mineral y fotosíntesis en plántulas de algarrobo blanco, Prosopis alba (Fabaceae), en estrés salino

“…La actividad NR depende fuertemente de la concentración de nitrato, ya que el propio sustrato induce su síntesis de novo (Carillo, et al, 2005). De este modo, las respuestas a largo plazo estarían mediadas por el suministro de nitrato, que a su vez depende de la transpiración y por ende de la apertura estomática, que puede disminuir como consecuencia del estrés salino (Gong et al,2013;Kawakami et al, 2013).…”

“…El efecto de la salinidad sobre la actividad nitrato reductasa depende de muchos factores, tales como la especie, fuente de nitrógeno, edad de la planta, concentración salina, y tiempo de exposición al estrés. Se ha reportado una disminución significativa en la actividad NR en hojas de Brassica juncea (Siddiqui, Mohammad, Khan, Mohamed & Al-Whaibi 2012), genotipos sensibles de trigo (Carillo et al, 2008;Yousfi, Serret, Márquez, Voltas & Araus, 2012), tomate (Gong et al, 2013), algodón (Kawakami, Osterhuis & Snider, 2013), girasol , Vigna unguiculata (Magalhães de Aragão, Silva, Lima & Silveira, 2011) y hojas y raíces de álamo (Ehlting et al, 2007) sometidas a estrés con NaCl. Por el contrario, el estrés salino incrementó la actividad nitrato reductasa en raíces de pepino (Reda, Migocka & Klobus, 2011) y tomate (Debouba, Maâroufi-Dghimi, Suzuki, Ghorbel & Gouia, 2007).…”