Search

Nitrogen (N) is one of the primary macronutrients required for crop growth and yield. This nutrient is especially limiting wheat yields in the dry and low fertile agro-ecologies having low N in the root zone soil strata. Moreover, majority of farmers in India and South Asia are small to marginal with meagre capacity to invest in costly nitrogen fertilizers. Therefore, there is an immense need to identify lines that use nitrogen efficiently. A set of 50 diverse wheat genotypes consisting of indigenous germplasm lines (05), cultivars released for commercial cultivation (23) and selected elite lines from CIMMYT nurseries (22) were evaluated in an alpha-lattice design with two replications, a six-rowed plot of 2.5m length for 24 agro morphological, physiological and NUE related traits during two consecutive crop seasons in an N-depleted precision field under two different N levels of 50%-N50 (T1) and 100%-N100 (T2) of recommended N, i.e., 100 kg/ha. Analysis of variance revealed significant genetic variation among genotypes for all the traits studied. About 11.36% yield reduction was observed at reduced N levels. Significant correlations among NUE traits and yield component traits were observed which indicated pivotal role of N remobilization to the grain in enhancing yield levels. Among N-insensitive genotypes identified based on their yielding ability at low N levels, UASBW13356, UASBW13358, UASBW13354, UASBW13357 and KRL1-4 showed their inherent genotypic plasticity toward N application. The genotypes with more yield and high to moderate NUtE can be used as parents for the breeding of N efficient genotypes for marginal agro-ecologies. Low N tolerant genotypes identified from the current investigation may be further utilized in the identification of genomic regions responsible for NUE and its deployment in wheat breeding programs. The comprehensive data of 24 traits under different nitrogen levels for diverse genotypes from India and global sources (mainly CIMMYT) should be useful for supporting breeding for NUE and thus will be of great help for small and marginal farmers in India and South Asia. [ABSTRACT FROM AUTHOR]

Highlights • Fifty wheat lines targeting semi-arid locations in India and Bangladesh were investigated. • Highly significant differences were observed for the six fodder traits investigated. • No significant relationship was seen between straw yield and fodder quality, but were observed between straw N and grain yield and between straw ADF and straw yield. • Results suggest that the best lines could meet the highest quality criteria observed in wheat straw trading with price premiums of 10 to 17%. • Wheat lines with superior straw traits can be useful as donor parents in future breeding programs in South Asia. Abstract Fifty wheat lines targeting semi-arid locations in India and Bangladesh were investigated for grain and straw yield and straw fodder quality traits for two consecutive years at two locations in India and one in Bangladesh. Fodder traits investigated were nitrogen (N), neutral detergent fiber (NDF), acid detergent fiber (ADF), acid detergent lignin (ADL), in vitro organic matter digestibility (IVOMD), and metabolizable energy content (ME). Highly significant (P < 0.0001) differences among lines were observed for all the traits, but location and year generally had greater effects than line. There were no significant relationships between straw yield and straw fodder quality traits. However, inverse associations (P = 0.17) were observed between straw N and grain yield and between straw ADF and straw yield. Variations among fodder quality within a location were slightly higher than when averaged across locations. For example, ADF, a trait significantly inversely correlated with price differences in wheat straw trading, ranged from 49 to 50.8% across locations whereas it ranged from 44.8 to 47.8% and from 47.2 to 49.6% at the two India sites and from 53.9 to 55.9% at the Bangladesh site. Moderate broad sense (h2) heritabilities were observed for ADF (h2 = 0.31) and ADL (h2 = 0.34), whereas h2 for other fodder traits were very low. Extrapolation of mean differences among lines in straw fodder quality traits across locations and years suggests that the best lines could meet the highest quality criteria observed in wheat straw trading with price premiums of 10–17% depending on whether the trading occurred in a rural or an urban area, respectively. [ABSTRACT FROM AUTHOR]