Nitrogen nutrition and wheat growth in relation to absorbed solar radiation

Estimation à partir de mesures de réflectance spectrale du rayonnement photosynthétiquement actif absorbé par une culture de blé

“…Le rendement éner-gétique de ces processus peut être formalisé simplement à l'échelle instantanée par le produit de deux facteurs (Monteith, 1972;Varlet-Grancher et al, 1982). Le (Varlet-Grancher et al, 1982;Gosse et al, 1986;Green, 1987;Olioso, 1987;Garcia et al, 1988 (1984), Asrar et al (1984), Hatfield et al (1984), Daughtry (1988). Ces résul-tats ont été confirmés à partir de considérations théoriques par Sellers (1985), Kumar (1988), Baret & Major (1988 (1984,1985).…”

Solar Radiation Effect on Crop Production

“…Nitrogen deficiency should decrease the range where there is a linear response between PAR and increased light and thus the range of maximum RUE (Sinclair, 1990;Muchow, 1988). A substantial decrease in RUE under nitrogen stress has been reported for maize (Muchow & Davis, 1988;Muchow, 1994), sorghum (Muchow, 1988), kenaf (Muchow, 1992), wheat (Green, 1987), sunflower (Hall et al, 1995 andBange et al, 1997), and peanut (Wright et al, 1993). Uhart & Andrade (1995) showed the differences in RUE produced in a crop of corn with nitrogen and without nitrogen, the latter being 40% lower ( Figure 7).…”

“…Thus, a favorable crop nitrogen status appears to be necessary for the realization/expression of maximum RUE in a given crop species. Several studies have reported a positive response of RUE to N fertilization in a number of crops (Muchow & Sinclair, 1994;Hall et al, 1995;Green, 1987). Nitrogen deficiency should decrease the range where there is a linear response between PAR and increased light and thus the range of maximum RUE (Sinclair, 1990;Muchow, 1988).…”

Root biomass fraction as a function of growth degree days in wheat

“…There is some evidence that root and leaf development is synchronized (Colnenne et al, 1988;Klepper et al, 1984). Baldy (1973), Gallagher and Biscoe (1978), Green (1987) and Hamblin et al (1990), among others, agree on a continuous decrease in f~ or f, from about 0.6 at the early stages to around 0.10 at maturity. However, for a given phenological stage, f~ or f, can vary greatly depending on soil and climatic conditions.…”