The normalized difference vegetation index (NDVI) continues to provide easy and fast methodologies to characterize wheat genetic resources in response to abiotic stresses. This study identifies ways to maximize green leaf area duration during grain filling and develops NDVI models to predict physiological maturity and different stay −green parameters to increase grain yield of rainfed winter wheat under terminal drought. Three wheat populations were evaluated: one containing 240 landraces from Afghanistan, the second with 250 modern lines and varieties, tested for two years under low rainfall conditions in Turkey, and the third with 291 landraces from Central and Western Asia (grown for one year in the same location). The onset of senescence, maximum “greenness”, rate of senescence and residual “greenness” at physiological maturity were estimated using sequential measurements of NDVI and have shown significant correlations with grain yield under low rainfall rainfed conditions. Trade-offs were identified among the different stay −green attributes, e.g. delayed onset of senescence and high maximum “greenness” resulted in accelerated rates of senescence and highest yields and were most evident in the landrace populations. It is concluded, that the use of rate of senescence to select for stay −green must be coupled with other stay −green components, e.g. onset of senescence or maximum “greenness” to avoid the effects of the trade-offs on final grain yield. The NDVI decay curves (using the last three NDVI measurements up to maturity) were used to estimate days to maturity using the NDVI decay during the senescence period and days to heading. A training and testing set (20 and 80% of each population, respectively) were used for calibrations allowing for correlations between predicted and observed maturity of up to r = +0.85 (P < 0.0001). This procedure will facilitate large −scale wheat phenotyping in the future.
Maize-based crop rotations are advocated as alternate to rice-based systems in South Asia due to better suitability for diverse ecologies, higher yields with less water use and more palatable maize fodder compared to rice, and increased demand of maize from piggery and poultry industries. Alternate tillage and crop establishment practices are important management strategies for tackling the issues of soil health deterioration and over exploitation of underground water resources, particularly in rice based intensive crop rotations. The conservation agriculture (CA) based tillage and crop establishment practices such as zero tillage (ZT) and permanent raised beds (PB) hold potential to enhance soil organic carbon (SOC), physical and biological properties for sustainability of soil health. Therefore, a long term study was conducted to evaluate the twelve combinations of tillage practices (03) and irrigated intensive maize based crop rotations (04) on organic carbon, physical properties and microbial biomass and enzymatic activities of a sandy loam (Typic Haplustept) soil in north-western India. The tillage practices consisted of ZT, PB and conventional tillage (CT) in main plots and four diversified intensive maize based crop rotations (MWMb: Maize-Wheat-Mungbean, MCS: Maize-Chickpea-Sesbaina, MMuMb: Maize-Mustard-Mungbean, MMS: Maize-Maize-Sesbania) in sub plots. In this study we analysed the SOC, physical and biological properties of soil at various depths after 7 years of continuous ZT, PB and CT in diversified maize rotations. Compared to CT plots, the soil physical properties like water stable aggregates (WSA) > 250 μm were 16.1-32.5% higher, and bulk density (BD) and penetration resistance (PR) showed significant (P < 0.05) decline (11.0–14.3 and 11.2–12.0%) in ZT and PB plots at 0–15 and 15–30 cm soil layers. The soil organic carbon (SOC) increased by 34.6-35.3% at 0–15 cm, and 23.6-26.5% at 15–30 cm soil depths with conservation agriculture (ZT and PB) based crop establishment techniques over CT. Similarly, the soil microbial biomass carbon (MBC) under CA based systems increased by 45–48.9% in 0–30 cm profile depth of a sandy loam (Typic Haplustept) soil. Significant (P < 0.05) improvement in soil enzymatic activities i.e., Fluorescein diacetate, dehydrogenase, β Glucosidase and Alkaline phosphatase was also recorded in the CA based treatments. Significant (P < 0.05) synergistic effects of summer legumes (mungbean and Sesbania) with winter legume/cereal in crop rotations were observed on SOC,WSA, BD, PR and Ksat at 0–15 and 15–30 cm depths. Interaction between tillage and crop rotations were significant (P < 0.05) for soil organic carbon, physical properties and enzymatic activities. Thus our long-term study suggests that CA based crop management with selected diversified maize based rotations (MCS and MWMb) can be advocated as sustainable intensification strategy in light textured soils of north-western India and other similar agro-ecologies of South Asia.
The maize-wheat-mungbean (MWMb) cropping system is being advocated as an alternative to the traditional rice-based cropping systems of north-western Indo-Gangetic Plains (IGP) to address the issues of energy and nutritional scarcity, residue burning, decline in biomass productivity and water tables. In semi-arid regions, the climate-change-induced variability in rainfall and temperature may have an impact on phenological responses of cereals and pulses which in turn would affect biomass production, economic yield and energy and water-use efficiency (WUE) of the crops. Henceforth, quantification of bioequivalent yields, energy requirement, economics and WUE of MWMb system is essentially required owing to have better understanding of this cropping system. Following a 4-year study was conducted under different tillage and nutrient management. ZT and PB plots had significantly higher pooled average (17.2–20.3%) biomass productivity, (34.4–39.8%) net returns and (49.8–66.2%) biomass water-use efficiency with lesser (8.5–16.1%) water-use than the CT plots. Significantly higher pooled bioenergetic yields (21.7–35.2%), net returns (31.4–37.8%) and biomass water-use efficiency (30.1–35.2%) was observed in SSNM/Ad-hoc plots compared with FFP plots. The total pooled energy input in ZT/PB and SSNM/Ad-hoc plots was significant (P < 0.05) higher than CT and FFP plots, respectively, with greater net energy output, energy productivity and energy efficiency. The interactions between tillage and nutrient management practices on pooled input energy and energy productivity of MWMb system was significant (P < 0.05). Thus, adoption of conservation tillage (ZT/PB) practices with improved nutrient management (SSNM/Ad-hoc) could be a viable option for achieving higher biomass productivity, water and energy-use efficiency and profitability in MWMb system.
Rainfall simulator trials were conducted on sugar cane paddocks across dry-tropical and subtropical Queensland, Australia, to examine the potential for spot spraying to reduce herbicide losses in runoff. Recommended rates of the herbicides glyphosate, 2,4-D, fluoroxypyr, atrazine, and diuron were sprayed onto 0, 20, 40, 50, 70, or 100% of the area of runoff plots.
Simulated rainfall was applied 2 days after spraying to induce runoff at one plant cane and three ratoon crop sites. Over 50% of all herbicides were transported in the dissolved phase of runoff, regardless of the herbicide’s sediment−water partition coefficient.
For most sites and herbicides, runoff herbicide concentrations decreased with decreasing spray coverage and with decreasing herbicide load in the soil and cane residues. Importantly, sites with higher infiltration prior to runoff and lower total runoff had lower runoff herbicide concentrations.
Genomic and pedigree predictions for grain yield and agronomic traits were carried out using high density molecular data on a set of 803 spring wheat lines that were evaluated in 5 sites characterized by several environmental co-variables. Seven statistical models were tested using two random cross-validations schemes. Two other prediction problems were studied, namely predicting the lines’ performance at one site with another (pairwise-site) and at untested sites (leave-one-site-out). Grain yield ranged from 3.7 to 9.0 t ha−1across sites. The best predictability was observed when genotypic and pedigree data were included in the models and their interaction with sites and the environmental co-variables. The leave-one-site-out increased average prediction accuracy over pairwise-site for all the traits, specifically from 0.27 to 0.36 for grain yield. Days to anthesis, maturity, and plant height predictions had high heritability and gave the highest accuracy for prediction models. Genomic and pedigree models coupled with environmental co-variables gave high prediction accuracy due to high genetic correlation between sites. This study provides an example of model prediction considering climate data along-with genomic and pedigree information. Such comprehensive models can be used to achieve rapid enhancement of wheat yield enhancement in current and future climate change scenario.
The relationship of dietary vitamin A transfer from mother to fetus is not well understood. The difference in swine offspring liver reserves was investigated between single-dose vitamin A provided to the mother post-conception compared with continuous provitamin A carotenoid dietary intake from biofortified (enhanced provitamin A) orange maize (OM) fed during gestation and lactation. Vitamin A-depleted sows were fed OM (n = 5) or white maize (WM) + 1.05 mmol retinyl palmitate administered at the beginning of gestation (n = 6). Piglets (n = 102) were killed at 0, 10, 20, and 28 d after birth. Piglets from sows fed OM had higher liver retinol reserves (P < 0.0001) and a combined mean concentration from d 10 to 28 of 0.11 ± 0.030 μmol/g. Piglets from sows fed WM had higher serum retinol concentrations (0.56 ± 0.25 μmol/L; P = 0.0098) despite lower liver retinol concentrations of 0.068 ± 0.026 μmol/g from d 10 to 28. Milk was collected at 0, 5, 10, 20, and 28 d. Sows fed OM had a higher milk retinol concentration (1.36 ± 1.30 μmol/L; P = 0.038), than those fed WM (0.93 ±1.03 μmol/L). Sow livers were collected at the end of the study (n = 3/group) and had identical retinol concentrations (0.22 ± 0.05 μmol/g). Consumption of daily provitamin A carotenoids by sows during gestation and lactation increased liver retinol status in weanling piglets, illustrating the potential for provitamin A carotenoid consumption from biofortified staple foods to improve vitamin A reserves. Biofortified OM could have a measurable impact on vitamin A status in deficient populations if widely adopted.
Evaluation of wheat for spot blotch disease resistance relies on various visual observation methods. The person evaluating the lines needs to be experienced in scoring disease severity. To facilitate
The wheat line ‘Chapio’ is resistant to leaf rust, caused by Puccinia triticinia, and was derived from a breeding programme that focuses on multi-genic resistance to provide durability. This line was crossed with the susceptible ‘Avocet’ to develop an F6 recombinant inbred line population. The population was phenotyped for leaf rust severity in two environments each in Mexico and China. There were significant differences in the loci providing resistance between the two intercontinental regions. The Lr34 locus had large effects in both Mexico and China, highlighting its importance in providing a basis for broad-spectrum resistance. The Lr46 locus on chromosome 1BL and a 3D locus had effects in Mexico but not in China. Presence of Sr2 was determined by the phenotypic marker of pseudo-black chaff and was mapped to chromosome 3BS. This region was associated with a QTL that had strong effects in China but no significant effect in Mexico, as did a locus on chromosome 4B. Seedling tests on the parents indicated that the 3B locus was not the complimentary gene Lr27, but the 4B locus was in the same position as Lr31 (or Lr12). Further investigations showed that these loci worked independently and additively in adult plants. Chapio was bred for quantitative, non-race-specific resistance under strong phenotypic selection for leaf rust in Mexico. It is interesting that different QTLs contribute to this resistance in another country, and these results suggest that environmental effects, as well as race specificity, can play a role in expression of resistance.
Published in: Frontiers in genetics, 2016, vol.7, no.201.
Wheat landraces in Turkey are an important genetic resource for wheat improvement. An exhaustive 5-year (2009–2014) effort made by the International Winter Wheat Improvement Programme (IWWIP), a cooperative program between the Ministry of Food, Agriculture and Livestock of Turkey, the International Center for Maize and Wheat Improvement (CIMMYT) and the International Center for Agricultural Research in the Dry Areas (ICARDA), led to the collection and documentation of around 2000 landrace populations from 55 provinces throughout Turkey. This study reports the genetic characterization of a subset of bread wheat landraces collected in 2010 from 11 diverse provinces using genotyping-by-sequencing (GBS) technology. The potential of this collection to identify loci determining grain yield and stripe rust resistance via genome-wide association (GWA) analysis was explored. A high genetic diversity (diversity index = 0.260) and a moderate population structure based on highly inherited spike traits was revealed in the panel. The linkage disequilibrium decayed at 10 cM across the whole genome and was slower as compared to other landrace collections. In addition to previously reported QTL, GWA analysis also identified new candidate genomic regions for stripe rust resistance, grain yield, and spike productivity components. New candidate genomic regions reflect the potential of this landrace collection to further increase genetic diversity in elite germplasm.
Published in: Agricultural Economics, 2016, vol. 47 (supplement), p. 197-214
Mexico is the center of origin of diversification of maize (Zea mays L.), there are 3.2 million corn growers and is the largest crop harvested. Most of these producers are in the rural sector, in poverty and inequality. Despite this genetic diversity and represent about 65% of the cultivated area it is little attention has been given to the potential of native maize in commercial terms. The marketing of landraces can be carried out in traditional local markets and specialty markets. This research aimed to identify the dynamics of actual marketing of native maize in Mexico in order to identify options trading in specialty markets for the conservation of the biodiversity of these corns and improve the income of producers. The 492 interviews were made with farmers, traders and processors of native maize customers in the states of Mexico, Tlaxcala and Guerrero. The results show that the main specialty corns produced are the colors and within these the most important in marketing are the targets by consumer preferences corns. It is concluded that currently the market is landraces in traditional local markets; however there is potential for the development of specialty markets that require value added.