Contrasting growth pattern and nitrogen economy in ancient and modern wheat varieties

Abstract

Pourazari, F., Vico, G., Ehsanzadeh, P. and Weih, M. 2015. Contrasting growth pattern and nitrogen economy in ancient and modern wheat varieties. Can. J. Plant Sci. 95: 851Á860. Nutrient availability, especially nitrogen (N) availability, is a limiting factor for crop production in many regions of the world. Modern crop varieties often produce high yields under high resource availability, whereas ancient varieties are expected to have characteristics more suitable under low resource availability. To test this expectation, we compared the growth and N use efficiency (NUE) of some varieties of ancient hulled wheat, Triticum turgidum spp. dicoccum, and modern free-threshing wheat, T. aestivum and T. turgidum spp. durum. The wheats were grown under different nutrient fertilization (F) levels in two contrasting environments (field in Iran and outdoor growth container in Sweden). Grain yield was significantly higher in modern varieties than in ancient varieties, regardless of fertilization level. In contrast, N uptake efficiency (i.e., mean N in the plant during the main growth period over N in the initial seed grain) and grain N concentration were generally higher in the ancient varieties. Nitrogen use efficiency, defined as the ratio of the grain N content to the sown seed N content, was higher in the ancient varieties only at lower nutrient supply, because in modern varieties higher nutrient supply resulted in a marked increase in NUE through greatly enhanced grain-specific N efficiency (grain yield per mean plant N content during the main growth period). The modern varieties also showed greater fertilization responses in above-ground biomass and leaf area than ancient varieties. The results are relevant in the context of wheat breeding for nutrient use efficiency. La quantite´de nutriments disponible, particulie`rement l'azote (N), fait partie des facteurs qui limitent la production agricole dans maintes re´gions du monde. Les varie´te´s contemporaines donnent souvent un haut rendement quand les ressources ne manquent pas alors que les varie´te´s anciennes ont des caracte`res qui se preˆtent davantage a`la rare´faction des ressources. Pour le ve´rifier, les auteurs ont compare´la croissance et l'efficacite´de l'utilisation de l'azote (NUE) de quelques varie´te´s de l'antique ble´monde´Triticum turgidum spp. dicoccum et du ble´moderne, sans battage, T. aestivum et T. turgidum spp. durum. Le ble´a e´te´cultive´sous divers re´gimes de fertilisation dans deux milieux contrastants (au champ, en Iran, et dans un conteneur exte´rieur, en Sue`de). Le rendement grainier des varie´te´s modernes e´tait significativement plus e´leve´que celui des varie´te´s anciennes, peu importe le degre´de fertilisation. En revanche, l'efficacite´de l'absorption du N (c.-a`-d. la concentration moyenne de N dans la plante pendant la principale pe´riode de croissance comparativement a`la concentration de N initiale dans la graine) et la concentration de N dans le grain sont ge´ne´ralement plus e´leve´es chez les varie´te´s antiques. La NUE, q...

Evidence for magnesium–phosphorus synergism and co-limitation of grain yield in wheat agriculture

“…The scaling exponent between N and P found in our study is low compared to the ones reported for other plants, suggesting that P possibly was limiting growth and yield in our study. However, the scaling exponents between N and P reported for other plants are usually interpreted in relation to vegetative plant growth but not crop (grain) yields; and vegetative biomass was uncorrelated with grains biomass in our study and other investigations 30 , 31 . In addition, higher grains biomass was associated with lower P concentrations in the growing crop (Fig.…”

Comparative photosynthetic attributes of emmer and modern wheats in response to water and nitrogen supply

“…Moreover, in the latter study, N-induced enhancements in gas-exchange attributes were consistent with the increases in yield of the Italian emmer wheat accessions, which contradicts our findings on the Iranian emmer wheats. The negative response of emmer wheats to N supply can be partially related to earlier findings showing lack of ability to response to N fertilizer in the ancient wheats (Castagna et al 1996, Pourazari et al 2015. The discrepancies between our results and some of the previous reports might be due partly to the use of different plant material and mode, rate, and stage of N fertilization.…”

“…In other words, N and water are known to interact in influencing plant growth and seed and dry mass production (Kiani et al 2016). Even though suboptimal N concentrations are postulated to impose serious limitations to the photosynthetic functions and, subsequently, dry mass and seed yield production by modern varieties of many crop plants, some evidence suggests that this generalization may not be valid with less-developed ancient land races of some staple crops (Pourazari et al 2015). Furthermore, lack of sufficient water for irrigation, in one hand, and environmental concerns, such as environmental pollution due to excessive use of N, on the other, have inspired the quest for water-and N-use efficient crop species.…”