Fertilization expression via nitrogen indices in soybean crop under two system tillage

Soybean (Glycine max L.) constitutes a crop that is currently of interest both for its nutritional properties in humans and animals and for its contribution to soil nitrogen. It belongs to legumes, that means that it can take N2 and channel it to the soil, to be assimilable from plants. In addition, its high oil and protein content makes it important because of its nutritional properties. Moreover, soybean is a crop that has a major impact on nitrogen indicators. In this study, set up two same experiments in 2018-2019, in Western Greece. There were identified the effects of different fertilizer application (Control, N80, N100, N120), and different tillage (conventional tillage (CT), no tillage (NT)), on soil (organic matter, root density, no nodules/soil) and in agronomic (LAI, height, N% in upper parts, Yield, N% in seeds, N uptake in upper parts, N uptake in seed, N total uptake) characteristics. As well as in nitrogen indicators (nitrogen use efficiency, nitrogen harvest index, nitrogen agronomic efficiency, effects of absorption, effects of uptake). Soil properties were affected mainly by the tillage. However agronomic characteristics presented more differences between the different fertilizer application and finally the indicators were affected on both the parameters.

Maize production and field CO2 emission under different straw return rates in Northeast China

In order to understand and clarify the impacts of straw return on maize production and field CO₂ emission in Northeast China, the most important agricultural base of the nation, a field experiment was conducted in 2012–2015, including no straw return (CK), straw amendment at 4000 kg/ha (S₄), and at 8000 kg/ha (S₈). The average grain yield was found significantly promoted by the two straw treatments, with comparably increased magnitudes of 11.0% and 12.8% for S₄ and S₈, respectively, and the benefits were gradually enlarged with increasing experimental duration. Although straw return tends to reduce slightly the harvest index, it was detected that it exerted significantly positive impacts on nitrogen harvest index. These results implied that added straw could lead to raising grain yield and enhancing nitrogen use efficiency simultaneously. In 2015, our monitoring showed that CO₂ emission was elevated with intensified use of straw, and S₄ and S₈ decreased carbon emission efficiency by 7.3% and 13.6%, respectively. However, there was no statistical difference between S₄ and CK. Overall, straw addition at the rate of 4000 kg/ha accompanied with inorganic fertilizer was recommended to be adopted in Northeast China, which was considered as a sustainable and relatively environment-friendly agricultural technique during maize production.

Phenotypic variability of bread wheat genotypes for nitrogen harvest index

Nitrogen harvest index (grain nitrogen content over total nitrogen content ratio) is a measure of the efficiency of nitrogen translocation from the vegetative portions of the plant to the grain. It can be recommended as a selection criterion for nitrogen use efficiency improvement. The aim of this study was to investigate nitrogen harvest index in twelve bread wheat genotypes at three nitrogen levels and to classify genotypes according to their phenotypic similarity for the examined trait. The results of factorial ANOVA showed that nitrogen harvest index was influenced mostly by the year ? genotype interaction, year of investigation and genotype; and to the lowest extent by the applied nitrogen rate. Increasing nitrogen doses did not lead to the increased nitrogen harvest index. The calculated nitrogen harvest index values were the highest for wheat growing season 2004/05, and the smallest for the season 2006/07. The highest nitrogen harvest indices were calculated for cultivars Pobeda at the N0 rate and Zlatka at the N100 rate (0.93), and the lowest for cultivar Tamaro at the N0 rate (0.63). Analyzing the constructed dendogram, cultivars Pobeda and Renan at all three levels of nitrogen supply can be singled out as the genotypes with the highest, and cultivar Tamaro as the variety with the lowest harvest index value. The results of this study may be used in developing new high-yielding bread wheat cultivars with improved nitrogen use efficiency. Growing such cultivars would provide the savings in mineral fertilizers and minimize their possible harmful effect on environment.

AMMI analysis of nitrogen harvest index in bread wheat

Nitrogen harvest index - NHI is a measure of efficiency of nitrogen translocation from vegetative organs to grain. The goal of this paper is to investigate variability and stability of nitrogen harvest index of twelve bread wheat genotypes, on three nitrogen levels. ANOVA showed that nitrogen harvest index was mostly under influence of the year x genotype interaction, year of investigation and genotype, and in the smallest amount of the nitrogen rate. Increasing doses of nitrogen did not lead to increased nitrogen harvest index. AMMI analysis showed that most genotypes differed in both the main effect and in GxE interaction. The highest stability i.e. the smallest interaction effect, was found in varieties Axis, Ilona, Sonata and Renan on N0 rate, and in varieties Malyska, Petrana, Axis and Evropa 90 on N100 rate. Cultivar Pobeda with the high average values for nitrogen harvest index, also had small interaction effect, i.e. it proved to be a stable variety.

Physiological characteristics of recent Canada Western Red Spring wheat cultivars: Components of grain nitrogen yield

Genetic yield gains have been difficult to achieve within the Canada Western Red Spring (CWRS) wheat (Triticum aestivum L.) class, partially because of the requirement for high protein concentration. A previous study indicated that four newer, high-yield CWRS cultivars (registered 1994–1997) also had higher protein yields. The objective of the present study was to determine if the increase in grain nitrogen (protein) yield of the four newer wheat cultivars, relative to two older cultivars, Neepawa (registered in 1969) and Marquis (introduced in 1909), resulted from increased plant nitrogen uptake, more efficient utilization of nitrogen, or a combination of these factors. The higher nitrogen yields were primarily attributed to more efficient utilization and redistribution of the nitrogen rather than increased uptake of soil nitrogen. The nitrogen harvest index (NHI) of the new cultivars, considered as a group, was higher than the NHI of Neepawa, which in turn was higher than that of the much older cultivar Marquis. The NHI of each of the new cultivars was higher than that of Marquis. The nitrogen concentration in the non-grain tissue at maturity (NGNCM) of the new cultivars, considered as a group, was lower than that of Neepawa, which in turn was lower than the NGNCM of Marquis. At maturity, all five tissues (leaf blade, stem plus sheath, peduncle, glume, and rachis) for the new cultivars and Neepawa had lower nitrogen concentrations than for the corresponding tissues of Marquis. The nitrogen concentration of the peduncle and leaf-blade tissues of the new cultivars, as a group, were also lower at maturity than the corresponding nitrogen concentrations for Neepawa. The results suggest that low non-grain nitrogen concentration at harvest is associated with improved NHI and grain nitrogen yield in CWRS wheat. This information may improve our understanding of the higher protein yields that have been achieved within this class, and assist in the selection of future parents. Key words: Nitrogen harvest index, nitrogen uptake, nitrogen yield, protein, remobilization, Triticum aestivum