Water and energy footprints of bioenergy crop production on marginal lands

Water and energy demands associated with bioenergy crop production on marginal lands are inextricably linked with land quality and land use history. To illustrate the effect of land marginality on bioenergy crop yield and associated water and energy footprints, we analyzed seven large‐scale sites (9–21 ha) converted from either Conservation Reserve Program (CRP) or conventional agricultural land use to no‐till soybean for biofuel production. Unmanaged CRP grassland at the same location was used as a reference site. Sites were rated using a land marginality index (LMI) based on land capability classes, slope, soil erodibility, soil hydraulic conductivity, and soil tolerance factors extracted from a soil survey (SSURGO) database. Principal components analysis was used to develop a soil quality index (SQI) for the study sites based on 12 soil physical and chemical properties. The water and energy footprints on these sites were estimated using eddy‐covariance flux techniques. Aboveground net primary productivity was inversely related to LMI and positively related to SQI. Water and energy footprints increased with LMI and decreased with SQI. The water footprints for grain, biomass and energy production were higher on lands converted from agricultural land use compared with those converted from the CRP land. The sites which were previously in the CRP had higher SQI than those under agricultural land use, showing that land management affects water footprints through soil quality effects. The analysis of biophysical characteristics of the sites in relation to water and energy use suggests that crops and management systems similar to CRP grasslands may provide a potential strategy to grow biofuels that would minimize environmental degradation while improving the productivity of marginal lands.     

CO2 fluxes of transitional bioenergy crops: effect of land conversion during the first year of cultivation

The present study examined the effect of land conversion on carbon (C) fluxes using the eddy covariance technique at seven sites in southwestern Michigan (USA). Four sites had been managed as grasslands under the Conservation Reserve Program of the USDA. Three fields had previously been cultivated in a corn/soybean rotation with corn until 2008. The effects of land use change were studied during 2009 when six of the sites were converted to soybean cultivation, with the seventh site kept as a grassland. In winter, the corn fields were C neutral while the CRP lands were C sources, with average emissions of 15 g C m^?2 month^?1. In April 2009, while the corn fields continued to be a C source to the atmosphere, the CRPs switched to C sinks. In May, herbicide (Glyphosate) was applied to the vegetation before the planting of soybean. After tilling the killed‐grass and planting soybean in mid June, all sites continued to be C sources until the end of June. In July, fields previously planted with corn became C sinks, accumulating 15–50 g C m^?2 month^?1. In contrast, converted CRP sites continued to be net sources of C despite strong growth of soybean. The conversion of CRP to soybean induced net C emissions with net ecosystem exchange (NEE) ranging from 155.7 (±25) to 128.1 (±27) g C m^?2 yr^?1. The annual NEE at the reference site was ?81.6 (±26.5) g C m^?2 yr^?1 while at the sites converted from corn/soybean rotation was remarkably different with two sites being sinks of ?91 (±26) and ?56.0 (±20.7) g C m^?2 yr^?1 whereas one site was a source of 31.0 (±10.2) g C m^?2 yr^?1. This study shows how large C imbalances can be invoked in the first year by conversion of grasslands to biofuel crops.     

Genetics of flowering time in bread wheat <Emphasis Type="Italic">Triticum aestivum</Emphasis>: complementary interaction between vernalization-insensitive and photoperiod-insensitive mutations imparts very early flowering habit to spring wheat

Time to flowering in the winter growth habit bread wheat is dependent on vernalization (exposure to cold conditions) and exposure to long days (photoperiod). Dominant Vrn-1 (Vrn-A1, Vrn-B1 and Vrn-D1) alleles are associated with vernalization independent spring growth habit. The semidominant Ppd-D1a mutation confers photoperiod-insensitivity or rapid flowering in wheat under short day and long day conditions. The objective of this study was to reveal the nature of interaction between Vrn-1 and Ppd-D1a mutations (active alleles of the respective genes vrn-1 and Ppd-D1b). Twelve Indian spring wheat cultivars and the spring wheat landrace Chinese Spring were characterized for their flowering times by seeding them every month for five years under natural field conditions in New Delhi. Near isogenic Vrn-1 Ppd-D1 and Vrn-1 Ppd-D1a lines constructed in two genetic backgrounds were also phenotyped for flowering time by seeding in two different seasons. The wheat lines of Vrn-A1a Vrn-B1 Vrn-D1 Ppd-D1a, Vrn-A1a Vrn-B1 Ppd-D1a and Vrn-A1a Vrn-D1 Ppd-D1a (or Vrn-1 Ppd-D1a) genotypes flowered several weeks earlier than that of Vrn-A1a Vrn-B1 Vrn-D1 Ppd-D1b, Vrn-A1b Ppd-D1b and Vrn-D1 Ppd-D1b (or Vrn-1 Ppd-D1b) genotypes. The flowering time phenotypes of the isogenic vernalization-insensitive lines confirmed that Ppd-D1a hastened flowering by several weeks. It was concluded that complementary interaction between Vrn-1 and Ppd-D1a active alleles imparted super/very-early flowering habit to spring wheats. The early and late flowering wheat varieties showed differences in flowering time between short day and long day conditions. The flowering time in Vrn-1 Ppd-D1a genotypes was hastened by higher temperatures under long day conditions. The ambient air temperature and photoperiod parameters for flowering in spring wheat were estimated at 25°C and 12 h, respectively.     

Effect of Chelating Agents and Metal Ions on Growth and Fertility in the Male Clones of the Moss Microdus brasiliensis (Dub.) Ther

The male gametophores of Microdus brasiliensis become fertileafter 48 d on basal medium. EDDH A increases gametophore numberand percentage of fertile gametophores at lower concentrations(10^–8-10^–6 mol dm^–3), whereas EDTA enhancesboth the responses at all levels (10^–8-10^–4 moldm^–3). Their iron salts increase gametophore number aswell as the number of fertile gametophores, and the latter effectis more striking. The number of antheridia per head also increaseswith Fe-EDTA, and at higher concentrations antheridia are induced4 d earlier. EDTA and Fe-EDTA-stimulated antheridia] formationis associated with a corresponding increase in endogenous iron.Copper content increases only at higher levels of EDTA and Fe-EDTA,and there is no correlation with the antheridial induction response.Salicylic acid increases the number of gametophores and thepercentage of fertile gametophores only at lower concentrations(10^–8-10^–6 mol dm^–3), and ferric citrate doesso at all levels. With salicylic acid, antheridia are induced3 d earlier. The number of gametophores as well as the percentageof fertile gametophores increases with the increase in coppersulphate concentration. Co-addition of EDTA (10^–5 moldm^–3) and copper sulphate inhibits both the responsesat higher levels. Among the chelating agents tried, Fe-EDTAis most effective in enhancing antheridial production. Key words: EDDHA, EDTA, Salicylic acid     

Effect of Some Known Growth Regulators on Growth and Fertility in Male Clones of the Moss Microdus brasiliensis (Dub.) Ther.

Among the auxins (IAA, 2,4-D, NAA and NOA) LAA proves inhibitoryfor antheridial formation. The rest promote this response, andNAA is most effective. Cytokinin (2iP) stimulates vegetativegrowth as well as antheridial formation, but the effect is morepronounced on the former. Interaction of kinetin and IAA provesbetter for antheridial production as compared to IAA alone.Gibberellic acid enhances gametangial induction as well as vegetativegrowth at lower levels (10^–8–10^–8 mol dm^–3).With abscisic acid both the responses are markedly reduced.Anti-auxins and cycocel promote antheridial production and vegetativegrowth. Testosterone is more potent than progesterone in promotingantheridial formation and vegetative growth. Key words: Fertility, growth hormones, moss