Identification and screening of nitrogen-efficient cotton genotypes under low and normal nitrogen environments at the seedling stage

Abstract

Background: Large quantities of nitrogen (N) fertilizer applied to cotton cropping systems support high yields but cause adverse environmental impacts such as N 2 O emission and water eutrophication. The development of cotton cultivars with higher N use efficiencies suitable for low-N conditions is therefore important for sustainable production. In this study, we evaluated 100 cotton genotypes in 2016 for N use efficiency and related traits at the seedling stage. Methods: Sand culture experiment was conducted with low N levels (0.01 g•kg − 1) or normal N levels (0.1 g•kg − 1). We investigated plant height, SPAD value (soil plant analysis development chlorophyll meter), dry weight, N accumulation, N utilization efficiency, and N uptake efficiency. Through descriptive statistics, principal component analysis and heatmap clustering analysis, we confirmed the evaluation index system of N-efficient genotypes and the classification of N-efficient genotypes. Results: Significant differences were observed among N levels and genotypes for all agronomic traits and N levels. Coefficients of variation varied greatly and ranged from 6.7~28.8 and 7.4~20.8 under low-N and normal-N treatment, respectively. All traits showed highly significant positive correlations with each other, except SPAD value. The principal components under both N levels were similar, showing that total dry weight, aboveground dry weight, total N accumulation, and N uptake efficiency were important components. We confirmed these four traits as suitable screening indexes for low N tolerance. Based on the results of heatmap clustering and scatter diagram analysis of N efficiency value, 10 genotypes were found low-N tolerant, in which five varieties were inefficient under both low and normal N conditions, while four varieties were found efficient under low-N conditions but inefficient under normal-N conditions. Only one variety was efficient under both low and normal-N conditions. Meanwhile, 20 genotypes were identified as low-N sensitive ones, in which 19 genotypes were inefficient under low-N conditions but efficient under normal-N conditions, one variety was inefficient under both low and normal-N conditions. Conclusion: We preliminarily identified Kashi as a low-N tolerant and N-efficient cotton genotype, and CCRI 64 as a low-N sensitive and N-inefficient cotton genotype. Further studies should be carried out to verify the yield and heritability effect of specific genotypes in the field.

Nitrogen preference and genetic variation of cotton genotypes for nitrogen use efficiency

“…Previously, we have screened and evaluated the NUE and biomass potential of 270 cotton genotypes, which are normally cultivated in the cotton-growing areas of China, under low and normal N in the pot culture. The top 100 genotypes were identified having contrasting NUE in response to low N, 24 from which six genotypes were again selected and used in hydroponic culture (data not published) to further screening of the genotypes based on their contrasting behavior for NUE. In the present study, the best two cotton genotypes comprising N-efficient (Z-1017) and N-inefficient (GD-89) were selected to know the preference of either ammonium or nitrate for cotton production and NUE in hydroponic culture.…”

“…Cotton ( Gossypium L.) known as white gold is the backbone of the world's natural textile and is grown all over the world in more than 50 countries . However, the high cost of production, especially of N fertilization is a major constraint for cotton growers . To reduce this costly component of crop production, there is an immediate need to know the preferred N source and to identify cotton genotype with high NUE.…”

“…23 However, the high cost of production, especially of N fertilization is a major constraint for cotton growers. 24 To reduce this costly component of crop production, there is an immediate need to know the preferred N source and to identify cotton genotype with high NUE. We hypothesized that N-efficient cotton genotype together with preferred N source will reduce the N fertilization, cost of production, human and environmental problems.…”

Untangling the molecular mechanisms and functions of nitrate to improve nitrogen use efficiency

“…), nitrogen‐efficient genotypes are still not being cultivated due to a lack of perfect genotypes and specific traits for selection. Generally, four nitrogen‐efficient types were classified in cotton . These are: genotypes that are efficient under both low and high nitrogen conditions, known as ideal genotypes (Class I), genotypes that are efficient under high nitrogen conditions and inefficient under low nitrogen conditions (Class 2), genotypes that are efficient under low nitrogen conditions and inefficient under high nitrogen conditions (Class 3), and the genotype which is inefficient under both low and high nitrogen condition (Class 4) (Fig.…”

Variations in Nitrogen Metabolism are Closely Linked with Nitrogen Uptake and Utilization Efficiency in Cotton Genotypes under Various Nitrogen Supplies

“…Cotton (Gossypium L.) is grown all over the world and is the backbone of the world's natural textile fibers [30]. Among the production inputs, high N fertilization is a big challenge that not only increases the cost for farmers but also brings environmental and human problems [31]. To reduce this costly component of crop production, there is an immediate need to identify and develop cotton genotypes with high NUEs.…”