Photosynthesis and Grain Growth of Wheat Under Extreme Nitrogen Nutrition Regimes During Maturation

Abstract

Nitrogen (N) is usually the limiting nutrient for yield of wheat (Triticum aestivum L.). However, spring and winter wheats in the Great Plains respond slightly to N during late developmental stages, suggesting that there is little requirement. Research was conducted to determine the effect of N nutrition during maturation on photosynthesis, the main source of assimilates for growth of grain, and to ascertain why wheat responds only slightly to late applications of N. The cultivar 'Len' was grown in complete hydroponic solution in a greenhouse until the jointing stage, when partial solutions containing 0, 0.15, 1.5, or 15 mM NaNO 3 plus all other nutrients were supplied until the plants matured. Plant growth, photosynthetic rate, and related traits were measured from 5 to 35 d after anthesis and at JOURNAL maturity. High rates of N markedly increased grain, leaf, and stem biomass of the plants as they matured. Photosynthetic rate, chlorophyll and N contents, and area index of leaves were increased simultaneously by N. Stomatal conductance differed greatly during late stages of maturation, when plants grown with low levels of N senesced and plants grown with high levels continued to accumulate assimilates. It was concluded that N greatly influences photosynthetic processes and grain growth during maturation of wheat, but responses in the field might be limited by remobilization of stored N and early senescence of plants from hot, dry conditions.

Impact of Nitrogen Addition on Physiological, Crop Total Nitrogen, Efficiencies and Agronomic Traits of the Wheat Crop under Rainfed Conditions

“…Like the present work, an increased net photosynthetic rate (A n ) was observed due to the application of N [34]. Gyuga et al [48] reported that N greatly influences photosynthetic processes, and deficiency of N leads to the declined photosynthesis. Similarly, Abid et al [49] in their findings concluded that management of N nutrition could build drought tolerance in wheat by maintaining higher photosynthetic activities and antioxidative defense system during vegetative growth periods.…”

Impact of Nitrogen Addition on Spring Wheat Physiological and Agronomic Traits Under Contrasting Environmental Conditions

“…Like our work, the increased net photosynthetic rate (An) was observed due to the application of N[34]. Gyuga et al[49] reported that N greatly influences photosynthetic processes, and deficiency of N leads to the declined photosynthesis. Similarly, Abid et al[50] in their findings concluded that management of N nutrition could build drought tolerance in wheat by maintaining higher photosynthetic activities and antioxidative defense system during vegetative growth periods.…”

The effects of nitrogen and neighbouring crops on maturation and timing of seed dispersal in Hordeum spontaneum Koch. and Brassica kaber (DC.)

“…This is because photosynthetic rate, chlorophyll and nitrogen contents, and leaf area index increase simultaneously by nitrogen. In fact, plants grown with low levels of nitrogen senesce soon while plants grown with high levels of nitrogen continue to accumulate assimilates (Gyuga et al, 2002).…”