B. Feil

Yield and quality components of silage maize in killed and live cover crop sods

Abstract In sloping areas with high precipitation, planting maize into live winter cover crop sods may help to alleviate the environmental problems associated with clean-tillage production systems of maize. The present study evaluates the performance of silage maize (Zea mays L.) under several cultivation methods: CC (conventional cropping system, i.e., maize was sown into the bare, autumn-ploughed soil); LGS/CK (maize was planted into a living Italian ryegrass (Lolium multiflorum Lam.) sod which was subsequently herbicidally killed); and LGS/MR (similar to LGS/CK, but the ryegrass was mechanically regulated). The research was conducted in the midlands of Switzerland on a fertile sandy loam under humid conditions during three cropping seasons. With 110 kg N ha−1 (fertilizer nitrogen plus mineral nitrogen of the soil at maize planting), the CC system was much more productive than were the LGS/CK and LGS/MR systems in terms of dry matter and nitrogen yields of maize. Increasing the nitrogen supply to 250 kg N ha−1 considerably reduced the yield advantage of CC over the LGS/CK and LGS/MR systems, indicating that nitrogen was the most limiting factor for maize yield in the mulch seeding systems. With 250 kg N ha−1, the LGS/CK and LGS/MR systems produced greater total yields of digestible organic matter (maize plus ryegrass) than did the CC system, whereas the total nitrogen yield was similar for all cropping systems. The whole-shoot concentrations of nitrogen were highest under CC, irrespective of the level of nitrogen supply. With 110 kg N ha−1, concentrations of phosphorus and magnesium were clearly higher for the mulch seeding systems. There were only minor differences among the cropping methods in the concentrations of potassium and calcium in the whole shoot. When 250 kg N ha−1 were applied, there were no significant variations among the cropping systems in the concentrations of minerals. Changes in the botanical composition of the cover crop sod and in the time and method of cover crop control may help to reduce the competition for nitrogen between maize and the living mulch.

Maize production in a grass mulch system – seasonal patterns of indicators of the nitrogen status of maize

Abstract In hilly regions with high precipitation, planting maize (Zea mays L.) into living mulches of winter cover crops may alleviate some of the problems (erosion, runoff of agrochemicals, nitrate leaching) associated with conventional maize cropping. Nitrogen was found to be more yield-limiting for maize planted into a grass sod than for traditionally grown maize. The aim of the present study was to follow the seasonal patterns of some indicators of the N status (whole-shoot concentrations of N and nitrate as well as leaf greenness, as measured by the SPAD 502 chlorophyll meter) of silage maize in three cropping systems. The experiments were conducted in the midlands of Switzerland, where annual precipitation is high (≥1000 mm), for 3 years. The cropping systems were PLOUGH (maize sown into the bare autumn-ploughed soil), GRASS/HERB (maize planted into a living, subsequently herbicidally killed Italian ryegrass [Lolium multiflorum Lam.] sod), and GRASS/MECH (similar to GRASS/HERB, but the growth of the ryegrass sod was mechanically regulated). Planting was done with a strip tillage seeder. There were two N treatments: 110 and 250 kg N/ha (inclusive of the mineral N content of the soil from 0 to 90 cm depth). With 110 kg N/ha, the following differences between the cultural systems were found: (i) as early as the 3rd leaf stage, PLOUGH maize exhibited higher whole-shoot concentrations of nitrate than sod-planted maize; (ii) between the 3rd and 6th leaf stages, chlorophyll meter measurements revealed that the uppermost unfolded leaves of PLOUGH maize were markedly greener than those of maize on the mulch seeding plots; (iii) from the 6th leaf stage onwards, PLOUGH maize showed a higher N concentration than did maize grown in grass swards. Under 250 kg N/ha, the differences between the cultivation methods were much less pronounced. It is concluded that efforts to optimize the environmentally friendly living mulch systems should focus on reducing the competition between maize and the cover crop for N.

Growth and ammonium:Nitrate uptake ratio of spring wheat cultivars under a homogeneous and a spatially separated supply of ammonium and nitrate

Abstract In a split‐root experiment, seedlings of two German spring wheat cultivars (Remus, Star) were grown hydroponically to investigate the effect of a homogeneous and a spatially separated supply of ammonium (NH4) and nitrate (NO3) (HS and SS, respectively) on the production and distribution of dry matter, and on the uptake of NH4 and NO3. Under HS, both halves of the seminal root system were exposed to a 1:1 mixture of NH4‐N and NO3‐N. At SS, one half of the seminal root system was fed with NH4, while the other half received NO3. The pH of the nutrient solutions was 6.5, and the nitrogen (N) concentration was 3 mM in all compartments. Plants grown under HS produced more shoot dry matter, and showed a higher concentration of N in the shoots and a higher NH4‐N: NO3‐N uptake ratio, while root dry matter and the root:shoot dry matter ratio were greater at SS. Irrespective of N form localization, cv. Star clearly favoured NH4 as source of N, while cv. Remus exhibited a more balanced NH4‐N: NO3‐N uptake ra...

Accumulation and partitioning of biomass and soluble carbohydrates in maize seedlings as affected by source of nitrogen, nitrogen concentration, and cultivar 1

Abstract Seedlings of four maize hybrids were grown hydroponically to investigate the impact of different N sources (Ca(NO3)2, (NH4)2SO4 and a 1:1 mixture of both) on (i) production and partitioning of root and shoot dry matter, (ii) concentration of soluble carbohydrates in roots and shoots and their partitioning to these plant parts, (iii) concentration of starch in the shoot, and (iv) N uptake. During the main phase of the experiments (duration 14d), the plants were grown in a greenhouse at 25/22°C day/night temperatures and a photoperiod of 16h. Nitrogen was supplied at three concentrations (2.8, 28, and 280 ppm). The root‐zone pH was 6.5. Under the lowest N supply, the N sources produced similar root and shoot dry matters. At the highest N level (280 ppm), NO3‐fed plants were superior. In contrast, the mixture of NH4 and NO3 − was optimum at 28 ppm. More or less pronounced N form by N concentration interactions were also found in the concentration and distribution of soluble carbohydrates and in all ...

Responses of roots to low temperatures and nitrogen forms

Throughout its life cycle, the development of the root system is finely tuned to the requirements of the whole plant. This is only possible because roots adapt to physical impedance, availability of nitrogen, phosphorus and water, and to thermal conditions. This paper concentrates on cereals during the early establishment of the plant.

Utilization of late-applied fertilizer nitrogen by spring wheat genotypes

Abstract To attain acceptable grain protein concentrations with high yielding wheat varieties, N uptake after flowering is desirable. The study examined genotypic differences in the utilization of lateapplied N fertilizer by wheat. Four spring wheat genotypes, grown at three early N levels (40, 90, 140 kg N ha −1 applied before EC 23) were supplied with 0, 50, 100 kg N ha −1 at heading. Nitrogen in the crop at maturity was related to above-ground biomass, grain yield, senescence and residual mineral N contents in the soil (0–100 cm depth). Nitrogen in the crop at maturity increased up to the highest late N level. At the lower early N levels, late infertile tiller production influenced the genotype-specific utilization of late applied N, predominantly by decreasing the N present in the fertile shoots. At the highest early N level (N140), which was not affected by late tillering, utilization of late-applied N was similar for each genotype, although the genotypes differed in above-ground biomass and senescence. At N140, apparent utilization of the late N applications was 64 (50 kg N ha –1 applied) and 55 (100 kg N ha −1 applied) per cent. Because residual mineral N contents in the soil at maturity showed no significant difference between the late N levels at N140, the poor fertilizer N utilization could not be ascribed to physiological restrictions, but was apparently due to losses of plant-available N caused e.g. by leaching, denitrification, or volatilization from the crop or microbial immobilization. Nitrogen harvest index was not reduced by late N applications. The results show that investigations on genotypic variation in late N uptake require accompanying examinations of the soil mineral N status.

Accumulation of dry matter and nitrogen by minimum-tillage silage maize planted into winter cover crop residues

The use of winter cover crops in conjunction with minimum tillage may eliminate or at least mitigate the environmental problems associated with traditional maize tillage. The main goal of the present research was to study the accumulation of nitrogen and dry matter in the tops of silage maize under three cropping systems: (1) PLOUGH (=maize sown into an autumn-ploughed soil), (2) NW/MT (maize sown into frost-killed residues of the non-winterhardy phacelia and white mustard cover crops, and (3) RYE/MT (=maize sown into a stubble of forage rye whose above-ground phytomass was removed from the field shortly before maize planting). The experiments were conducted in the Swiss midlands and in the Jura range. Averaged across the five environments (=site × year combinations) tested, dry matter and nitrogen yields of maize were highest under PLOUGH and lowest under RYE/MT. These differences occurred as early as the 3rd leaf stage and remained until the end of the growing season of maize, but there were significant (P <0.05) interactions between environment and cropping system. Total yields of dry matter and nitrogen (maize plus rye) of the RYE/MT system tended to be higher than the dry matter and nitrogen yields of maize in the other systems. The effect of method of seedbed preparation (rototilling vs. band rotary hoeing) on the yields of dry matter and nitrogen was not significant; there were no interactions between maize cropping system and manner of seedbed preparation. Under RYE/MT, both the mineral nitrogen content of the soil (0–90 cm depth) prior to maize sowing and the nitrogen concentration in the maize tops throughout the growing season of maize were relatively low, indicating that the rye cover crop reduced the nitrogen supply to the succeeding maize crop through pre-emptive competition.

Relationship between grain yield and grain nitrogen concentration in winter triticale

SummaryTen hexaploid winter triticale lines were grown for two cropping periods at three locations in western Switzerland. Averaged across the six environments, the differences between lines were statistically significant (P=0.05) for grain yield, above-ground biomass, N uptake, grain N yield, nitrogen harvest index, grain N concentration and straw N concentration. There were significant line x environment interactions for all traits. Grain yield and grain N concentration were inversely related (r=−0.74**). Diagrams in which grain yields were plotted against grain N concentration were used to identify lines with a consistently unusual combination of grain yield and grain N concentration. Despite comparable grain yields, Line 3 had a high grain N concentration, while that of Line 7 was low. Line 3 was superior to Line 7 in both N uptake and N harvest index. Averaged across environments and lines, the N harvest index was 0.73 which corresponds to N harvest indices reported for bread wheat in the same region. We considered the feasibility of developing triticale lines which would outperform the best recent ones in N uptake and partitioning. However, we doubted that this would bring about a marked increase in grain N concentration, because, in the long run, the expected genetic progress in grain yield will lead to a dilution of grain protein by grain carbohydrate increments.

Concentrations of minerals in the grains of a high- and a low-protein winter triticale.

Ten hexaploid winter triticales were grown at three sites in western Switzerland for two cropping periods. The grains were analyzed for their concentration of N. Averaged across the environments, entries 50728 and 50893, two advanced breeding lines, produced about the same grain yield but differed markedly in the concentration of grain N (Fossati, Fossati & Feil, 1993, Euphytica 71, p. 115–123). Research on wheat and other cereals has shown that concentrations of protein and minerals are often positively correlated. Therefore, it appears likely that high-protein triticales, such as entry 50728, will also exhibit elevated levels of minerals. Grain of entries 50728 and 50893, from our experimental site Changins, were used to test this hypothesis. The kernels were assayed for a number of nutritionally relevant mineral elements (P, K, Mg, Mn, Ca, Fe, Zn, and Cu) by ICP-AES. Averaged over the two cropping periods, 50728 grain was clearly higher in N, P, K, Ca, and Fe and slightly higher in Mg and Zn than those of entry 50893. There were no differences between the entries for Mn and Cu.