Biomass partitioning and nitrogen retranslocation in black spruce seedlings on competitive mixedwood sites: a bioassay study

Abstract

Black spruce (Picea mariana (Mill.) BSP) seedlings were exponentially nutrient loaded by applying 3 or 6 times more fertilizer than recommended for conventional seedling production in the nursery. Loaded seedlings were similar in height and biomass to nonloaded seedlings after nursery culture, but their tissue N, P, and K content was almost twice as much as that of nonloaded seedlings. The seedlings were transplanted on intact potted substrates (bioassays) retrieved with natural vegetation from two boreal mixedwood sites and grown for one season in a greenhouse to study early-and late-season growth and nutrient dynamics, and nutrient loading and herbicide effects on N retranslocation processes. After transplanting, height and biomass growth of loaded seedlings were, respectively, 9-14% and 24-49% more than nonloaded seedlings in herbicide-treated plots, and 14-32% and 42-85% more in untreated plots, resulting in 32-39% biomass reduction in natural vegetation. The effect of nutrient loading on growth was attributed to earlier and greater biomass and N partitioning to current needles and roots that promoted N uptake (up to 20.9 ± 1.7 mg) compared with nonloaded seedlings (up to 11.8 ± 1.2 mg). Although both loading and herbicide treatments stimulated seedling growth and N uptake, N retranslocation from older to actively growing tissues was promoted by loading but reduced by herbicide treatment. The results demonstrate the high dependence of seedlings on internal nutrient reserves when planted in competitive environments, and that nutrient retranslocation is mainly driven by current growth, nutrient uptake, and internal nutrient reserves.Résumé : Des semis d'épinette noire (Picea mariana (Mill.) BSP) ont été soumis à une consommation de luxe exponentielle en appliquant 3 et 6 fois les doses de fertilisant recommandées pour la production conventionnelle de semis en pépinière. Les semis ainsi traités étaient semblables en hauteur et en biomasse à ceux soumis à un régime normal après la culture en pépinière, mais le contenu de leurs tissus en N, P et K était presque deux fois supérieur à ceux-ci. Les semis ont été transplantés dans des pots contenant des substrats intacts prélevés sur deux stations de forêt boréale mixte en conservant la végétation naturelle et placés en serre durant une saison de croissance en vue d'étudier la dynamique nutritionnelle et la croissance en début et en fin de saison, de même que les effets des herbicides et de la consommation de luxe sur la retranslocation de N. Après la transplantation, la croissance en hauteur et la croissance en biomasse des semis soumis à la consommation de luxe étaient supérieures de 9-14% et de 24-49%, respectivement, par rapport aux semis soumis à un régime normal dans les parcelles traitées avec herbicide, et supérieures de 14-32% et 42-85% dans les parcelles non traitées, conduisant ainsi à une baisse de 32-39% de la biomasse végétale naturelle. L'effet de la consommation de luxe sur la croissance a été attribué à une allocation supérieure et plus précoce de N e...

Analysis of Nutritional Interactions in Cropping Systems

“…Excess fertilization (e) may induce toxicity, often indicated by decreased plant growth and N content but elevated tissue nutrient concentration. Such higher internal nutrient reserves acquired during nutrient loading have been shown to correlate well with improved field performance of tree seedlings (Salifu and Timmer 2003b;Malik and Timmer 1998). This simple model has been used to adapt the concept of steady-state nutrition to soilbased seedling culture by developing fertilizer delivery models which effectively induce steady state nutrition (Marney et al 2010) …”

“…2) probably because of retranslocation to the leaves. Malik and Timmer (1998) also used this diagnostic approach to study nutrient retranslocation in nutrient loaded and non-loaded black spruce seedlings planted on competitive boreal mixedwood forest sites. Thus, vector diagnosis approach can be used to study effects of different management regimes on both plant nutrient allocation and retranslocation processes.…”

Characterizing fertility targets and multi-element interactions in nursery culture ofQuercus rubraseedlings

“…Excess fertilization (e) may induce toxicity, often indicated by decreased plant growth and N content but elevated tissue N concentration. Higher internal nutrient reserves acquired during nutrient loading have correlated well with improved field performance of seedlings [28,37].…”

Morphology and foliar chemistry of containerized Abies fraseri (Pursh) Poir. seedlings as affected by water availability and nutrition

“…Previous studies manipulating nutrients and water levels have shown that increased height, diameter, and volume production were the result of improved production of photosynthates generated by greatly increased leaf area due to the establishment of non-limiting conditions based on irrigation and fertilization (Albaugh et al, 2004;Bergh et al, 1999). Past studies focused on the new growth of established trees, and the response occurred mainly in new shoots leading to the proposition that this was a reflection of withdrawal and retranslocation of resources to sinks of new growth (Malik and Timmer, 1998;McAlister and Timmer, 1998;Xu and Timmer, 1999). However, these processes studied under field conditions and on the new growth of established trees are not necessarily applicable to first or second year transplants, or containerized plants.…”