Plant development,agronomic performance and nutritive value of forage maize depending on hybrid and marginal site conditions at high latitudes

Abstract

The objectives of this investigation were to study the effects of marginal site conditions and hybrid on plant development, agronomic performance and nutritive characteristics of forage maize (Zea mays L.) at high latitudes. Field experiments were conducted in 2008 and 2009 at three experimental sites, Kristianstad, Skara and Västerås, at increasing latitudes from 55°–60° N. Experimental design used two replicated randomized complete blocks at each site with three maize hybrids, Avenir (FAO 180), Isberi (FAO 190) and Burli (FAO 210), which were continuously assessed for plant development and harvested at various levels of maturity. The chemical composition and nutritional characteristics of harvested plant materials were analysed and hybrid responses to advancing maturity in terms of yield and nutritional qualities were evaluated. Results showed that maize hybrids required different numbers of accumulated thermal units at sites on varying latitudes to achieve developmental stages. Lowest thermal unit requirements among hybrids were observed for hybrid Avenir, and for sites it was highest for plants grown in the most northern site, Västerås. The most southern site, Kristianstad, was the only site at which all hybrids reached the dent stage (c. 450 g kg^?1 kernel DM), a recommended maturity for ensiling. The DM yields of early maturing hybrid Avenir were consistently lower than those for Isberi and Burli at all the sites. Results also revealed nutritional differences among maize hybrids at a given maturity (DM, g kg^?1), indicating that the effects of maturation should be factored into design of hybrid performance trials. This study highlights the effects of marginal site conditions and hybrids on plant development, agronomic performance and nutritional characteristics of maize hybrids at high latitudes. Further studies on marginal sites are recommended to enlighten the understanding of interaction between environmental and genetic factors on the performance of forage maize.     

Prediction of nutritive values,morphology and agronomic characteristics in forage maize using two applications of NIRS spectrometry

This study evaluates nutritive, morphological and agronomic characteristics of forage maize predicted by using a high-quality near-infrared (NIR) spectrometer and an NIR hyperspectral-imaging technique using partial least squares (PLS) regression models. The study includes 132 samples of dried milled whole-plant homogenates of forage maize with variation in maturity, representing two growing seasons, three locations in Sweden and three commercial maize hybrids. The samples were measured by a classical sample cup NIR spectrometer and by a pushbroom hyperspectral-imaging instrument. The spectra and a number of variables (crude protein, CP, neutral detergent fibre, starch, water soluble carbohydrates (WSC) and organic matter digestibility), morphological variables (leaves, stems & ears) and crop yield were used to make PLS calibration models. Using PLS modelling allowed the determination of how well maize variables can be predicted from NIR spectra and a comparison of the two types of instruments. Most examined variables could be determined equally well, by both instruments, but the pushbroom technique gave slightly better predictions and had higher analytical capacity. Predictions of CP, starch, WSC and the proportions of ears in the maize gave robust. The findings open new possibilities to further utilise the technology in plant breeding, crop management, modelling and forage evaluation.     

Effect of Azospirillum and Azotobacter Species on the Performance of Cherry Tomato under Different Salinity Levels

Abiotic stress has a negative impact on plant physiology, influencing the overall growth and development of plant crops. Saline stress is one of the most serious environmental issues limiting crop plant production. Biofertilizers are reparative elements used in soil to increase tolerance to salinity and drought stress. We investigated the effect of salinity stress on qualitative and quantitative characteristics of cherry tomato plants (Lycopersicon esculentum cerasiforme) with biofertilizer application 0, 15 and 30 days after transplanting in this study. After different days of transplantation, different levels of salinity (0, 50, 100, and 150?mM) were used with biofertilizer (Azospirillum sp. and Azotobacter sp.) application (0, 15 and 30 days). The salinity (150?mM NaCl) significantly affected the studied variables, which were recorded with minimum levels of leaf area (52.42?cm²), root length (6.54?cm), fresh root weight (13.64?g), yield (6.52 tons/ha), leaf chlorophyll content (36.11?mg/m²) and maximum levels of total soluble solids (TSS, 8.87 °Brix). Control samples had higher leaf area (58.35?cm²), root length (15.23?cm), fresh root weight (17.86?g), yield (9.39 tons/ha), leaf chlorophyll content (44.09?mg/m²), and lower TSS (7.93 °Brix). Plants that received biofertilizer (15 days after transplanting) had higher plant height (73.41?cm), stem diameter (0.74?cm), leaf area (61.16?cm²), root length (15.35?cm), fresh root weight (18.38?g), root dry matter (60.41%), yield (10.43?t/ha), leaf chlorophyll content (42.55?mg/m²), fruit dry matter content (10.12?g), pH 4.52, and TSS (9.30 °Brix). The minimum plant height (51.33?cm), stem diameter (0.55?cm), leaf area (49.60?cm²), root length (7.04?cm), fresh root weight (12.76?g), root dry matter (42.16?g), yield (5.15 tons/ha), leaf chlorophyll content (35.18?mg/m²), fruit dry matter content (6.59?g), pH 4.27 and TSS (7.55 °Brix) were recorded in plants with no application of biofertilizer. The present study revealed that most growth and quality variables were negatively affected by salinity except for TSS, which showed positive effect with application of 150?mM of NaCl. Biofertilizer application at 15 days significantly influences the quantitative and qualitative attributes of cherry tomato under different levels of salinity.

     

Glyphosate hormesis in broad-leaved weeds: a challenge for weed management

Little is known of glyphosate-induced hormesis in weeds and how this might influence weed management. To test the hormetic effect of low doses of glyphosate on broad-leaved weeds, two experiments were conducted, in the laboratory and the screenhouse. The hormetic effects of glyphosate solution in growth media (0, 65, 130, 250, and 500 g acid equivalent (a.e) ha^?1) and foliar spray (0, 4, 8, 16, 32, and 64 g a.e. ha^?1) were tested on four broad-leaved weeds (Coronopus didymus, Chenopodium album, Rumex dentatus, and Lathyrus aphaca). Glyphosate solution in the range 65–250 g a.e. ha^?1 stimulated the germination and seedling growth of all tested weeds. However, at 500 g a.e. ha^?1 inhibition of germination and growth was observed. Foliarly applied glyphosate in the range 4–32 g a.e. ha^?1 increased root and shoot length, dry biomass, and seed production ability of all four weeds species; however, the stimulatory response was species dependent. These results indicate that glyphosate hormesis could play a significant role in altering crop/weed competition and might influence weed management.     

Understanding Interaction Patterns within Deep-Sea Microbial Communities and Their Potential Applications

Environmental microbes living in communities engage in complex interspecies interactions that are challenging to decipher. Nevertheless, the interactions provide the basis for shaping community structure and functioning, which is crucial for ecosystem service. In addition, microbial interactions facilitate specific adaptation and ecological evolution processes particularly essential for microbial communities dwelling in resource-limiting habitats, such as the deep oceans. Recent technological and knowledge advancements provide an opportunity for the study of interactions within complex microbial communities, such as those inhabiting deep-sea waters and sediments. The microbial interaction studies provide insights into developing new strategies for biotechnical applications. For example, cooperative microbial interactions drive the degradation of complex organic matter such as chitins and celluloses. Such microbiologically-driven biogeochemical processes stimulate creative designs in many applied sciences. Understanding the interaction processes and mechanisms provides the basis for the development of synthetic communities and consequently the achievement of specific community functions. Microbial community engineering has many application potentials, including the production of novel antibiotics, biofuels, and other valuable chemicals and biomaterials. It can also be developed into biotechniques for waste processing and environmental contaminant bioremediation. This review summarizes our current understanding of the microbial interaction mechanisms and emerging techniques for inferring interactions in deep-sea microbial communities, aiding in future biotechnological and therapeutic applications.