Boy Feil

Root morphology of Maize under homogeneous or spatially separated supply of ammonium and nitrate at three concentration ratios

Maize (Zea mays L. cv. Anjou 256) seedlings were grown hydroponically for 10 d in a split-root system (3mM N; pH 5.5) under either a homogeneous supply (HS) or a simultaneous, but spatially separated supply (SS) of NH 4 + and No 3 - . Treatments comprised three NH 4 + :NO 3 - ratios (1:4, 1:1,4:1). Shoot dry matter and various root traits (dry matter, number of laterals, length of main axes, total root length and total root surface area) were determined. For all NH 4 + :NO 3 - ratios, shoot dry matter, root dry matter, total root length, and root surface area, were greater under HS than under SS. Under both SS and HS, increasing NH 4 + :NO 3 - ratios resulted in decreased shoot and root dry matter production, but did not alter the shoot:root dry matter ratio. Under SS, root dry matter, root length, and root surface area was greater on the N0 3 - -fertilized side than on the NH 4 + -fertilized side. The allocation of root dry matter, root length, and root surface area to the NH 4 + or NO 3 - compartments was unaffected by changes in the NH 4 + :NO 3 - ratio. Enhanced NH 4 + nutrition has detrimental effects on top growth, but roots are apparently unable to avoid excessive NH 4 + uptake by proliferating in zones where N0 3 - is the only form of N.

Root Growth and Nitrate-Nitrogen Leaching of Catch Crops following Spring Wheat

Growing nitrogen (N) catch crops can reduce NO(3)-N leaching after cultivating cereals. The objective of this study was to relate NO(3)-N leaching to variation in the uptake of N and the size and distribution of the root systems of different catch crops species. In a 3-yr lysimeter experiment, phacelia (Phacelia tanacetifolia Benth.), sunflower (Helianthus annuus L.), and a Brassica species (yellow mustard [Brassica alba L.] or a hybrid of turnip rape [B. rapa L. spp. oleifera (DC.) Metzg.] and Chinese cabbage [B. rapa L. ssp. chinensis (L.) Hanelt]) were grown after the harvest of spring wheat under two levels of N supply. Bare soil lysimeters served as the control. Water percolation from the lysimeters and the NO(3)(-) concentration in the leachate were measured weekly from the sowing until the presumed frost-kill of the catch crops. Minirhizotrons were used to assess the spatial and temporal patterns of root growth from 0.10 to 1.00 m. The catch crop species differed in their shoot biomass, N uptake, total NO(3)-N leaching, and root growth. The results suggested that there was no strict relationship between the total NO(3)-N leaching of each catch crop species and the N uptake or parameters that indicate static characteristics of the root system. In contrast, the ranking of each catch crop species by parameters that indicate early root growth was inversely related to the ranking of each catch crop species in NO(3)-N leaching. The rapid establishment of the root system is essential for a catch crop following spring wheat to reduce the amount of NO(3)-N leaching after the harvest of spring wheat.

Sustainable agriculture and product quality: A case study for selected crops

Abstract “Sustainable agriculture” has been defined as a farming system with a low external input of agrochemicals, particularly fertilizer nitrogen. The impact of such farming systems on the quality of three arable crops was considered. Rape seed, wheat, and potato were selected, because they represent arable crops with simple to complex quality criteria. Rape seed (= simple quality criteria): The oil quality is determined primarily by the genotype and is only slightly affected by environmental conditions and cultural practices such as low nitrogen supplies. Within three decades, conventional breeding has changed rape seed into a new crop providing oil for human consumption instead for technical purposes. Wheat (= more complex quality criteria): Wheat is an excellent source of highly digestible energy for human consumption, but its most important quality criterion is the content of protein, which is positively correlated with baking quality and with contents of essential amino acids such as lysine and me...