SOIL QUALITY AND CROP PRODUCTIVITY AS AFFECTED BY DIFFERENT SOIL MANAGEMENT SYSTEMS IN ORGANIC AGRICULTURE "TILMAN-ORG Session"

A multi-year trial was conducted to compare soil management strategies (tillage and fertilization) with regard to their effect on crop performance and soil quality. Two soil management systems were assessed. Farm compost application was combined with reduced non-inversion tillage, whereas animal manure was incorporated by conventional tillage with a moldboard plough. With regard to soil quality, a reduced tillage practice in combination with compost application seemed to be favorable for soil quality of the surface layer in the short term. With regard to crop productivity, an effect of soil management strategy is less clear and dependent on a seasonal variation of growth circumstances

From lab to field : yield stability and shade avoidance genes are massively differentially expressed in the field

To unravel molecular mechanisms with the ultimate goal to achieve improved stress resilience or increased yield, plants are often studied under highly controlled conditions in which stresses are applied and in which growth‐ or architecture‐related traits are meticulously recorded. Over the past decades, this has led to a boost in our understanding of key molecular players and in strategies to improve yield stability. However, many single‐gene traits fail to translate into applications (Nuccio et al., 2018)

Grasslands and herbivore production in Europe and effects of common policies

The European project Multisward (http://www.multisward.eu/multisward_eng/) aims at supporting developments and innovations in grassland use and management in different European farming systems (including low-input and organic farming systems), pedoclimatic and socio-economic conditions i) to enhance the role of grasslands at farm and landscape levels to produce environmental goods and to limit the erosion of biodiversity and ii) to optimise economic, agronomic and nutritional advantages for the development of innovative and sustainable ruminant production systems. The identification of the innovations and their implementation required an exhaustive analysis of the state of grasslands and herbivore production in Europe including how they changed over decades. The effects of public policies were investigated. The results of this analysis are published in the present book

Overexpression of GA20-OXIDASE1 impacts plant height, biomass allocation and saccharification efficiency in maize

Increased biomass yield and quality are of great importance for the improvement of feedstock for the biorefinery. For the production of bioethanol, both stem biomass yield and the conversion efficiency of the polysaccharides in the cell wall to fermentable sugars are of relevance. Increasing the endogenous levels of gibberellic acid (GA) by ectopic expression of GA20-OXIDASE1 (GA20-OX1), the rate-limiting step in GA biosynthesis, is known to affect cell division and cell expansion, resulting in larger plants and organs in several plant species. In this study, we examined biomass yield and quality traits of maize plants overexpressing GA20-OX1 (GA20-OX1). GA20-OX1 plants accumulated more vegetative biomass than control plants in greenhouse experiments, but not consistently over two years of field trials. The stems of these plants were longer but also more slender. Investigation of GA20-OX1 biomass quality using biochemical analyses showed the presence of more cellulose, lignin and cell wall residue. Cell wall analysis as well as expression analysis of lignin biosynthetic genes in developing stems revealed that cellulose and lignin were deposited earlier in development. Pretreatment of GA20-OX1 biomass with NaOH resulted in a higher saccharification efficiency per unit of dry weight, in agreement with the higher cellulose content. On the other hand, the cellulose-to-glucose conversion was slower upon HCl or hot-water pretreatment, presumably due to the higher lignin content. This study showed that biomass yield and quality traits can be interconnected, which is important for the development of future breeding strategies to improve lignocellulosic feedstock for bioethanol production

Growth rate rather than growth duration drives growth heterosis in maize B104 hybrids

Research in maize is often performed using inbred lines that can be readily transformed, such as B104. However, because the B104 line flowers late, the kernels do not always mature before the end of the growing season, hampering routine seed yield evaluations of biotech traits introduced in B104 at many geographical locations. Therefore, we generated five hybrids by crossing B104 with the early-flowering inbred lines CML91, F7, H99, Mo17, and W153R and showed in three consecutive years that the hybrid lines proved to be suitable to evaluate seed yield under field conditions in a temperate climate. By assessing the two main processes driving maize leaf growth, being rate of growth (leaf elongation rate or LER) and the duration of growth (leaf elongation duration or LED) in this panel of hybrids, we showed that leaf growth heterosis was mainly the result of increased LER and not or to a lesser extent of LED. Ectopic expression of the transgenes GA20-oxidase (GA20-OX) and PLASTOCHRON1 (PLA1), known to stimulate the LER and LED, respectively, in the hybrids showed that leaf length heterosis can be stimulated by increased LER, but not by LED, indicating that LER rather than LED is the target for enhancing leaf growth heterosis. To enable transgenic maize research, hybrids between the inbred B104 that can be routinely transformed and early flowering inbreds were evaluated for yield components in three consecutive years. In addition, we show that leaf elongation rate is the main contributor to leaf growth heterosis in these hybrids, which can even be stimulated by overexpressing GA20OXIDASE, a known regulator of leaf elongation rate. Although leaf elongation duration has a limited contribution to the growth heterosis, the effect of the ectopic expression of PLASTOCHRON1, known to enhance leaf elongation duration and leaf growth, is still observed in the hybrids. This detailed understanding of the growth processes driving heterosis will be key to further breed for high yielding hybrids

The effect of tillage prctices on a leek crop's nitrogen utilization from a grass-clover sward

Adopting conservation agriculture practices in organic agriculture involves some risks and challenges. Nitrogen availability from a grass-clover ley for the subsequent leek crop was clearly affected by mode and timing of destruction of the grass-clover sward. Minor differences were found between a reduced tillage practice and conventional ploughing

Altered expression of maize PLASTOCHRON1 enhances biomass and seed yield by extending cell division duration

Maize is the highest yielding cereal crop grown worldwide for grain or silage. Here, we show that modulating the expression of the maize PLASTOCHRON1 (ZmPLA1) gene, encoding a cytochrome P450 (CYP78A1), results in increased organ growth, seedling vigour, stover biomass and seed yield. The engineered trait is robust as it improves yield in an inbred as well as in a panel of hybrids, at several locations and over multiple seasons in the field. Transcriptome studies, hormone measurements and the expression of the auxin responsive DR5(rev): mRFPer marker suggest that PLA1 may function through an increase in auxin. Detailed analysis of growth over time demonstrates that PLA1 stimulates the duration of leaf elongation by maintaining dividing cells in a proliferative, undifferentiated state for a longer period of time. The prolonged duration of growth also compensates for growth rate reduction caused by abiotic stresses