查看更多>>摘要：? 2022 Elsevier B.V.Being an affordable and good source of protein to a vast population that is vegetarian by choice or non-affordability of non-vegetarian food, legumes constitute a staple food in many Asian, African and Mediterranean countries. ‘Hidden hunger’- the deficiency of important mineral micronutrients such as iron and zinc- affects more than 2 billion people globally. Due to their global cultivation and ease of availability to the common masses, legumes are good candidates for biofortification to improve their nutritional quality, particularly for mineral micronutrients, and their bioavailability. Genetic biofortification either through classical breeding or molecular/transgenic approach is the most sustainable way to fortify a crop with nutrients. In the present review, we have critically analyzed and discussed different aspects pertaining to biofortification, like nutrient (iron and zinc) uptake, translocation and bioavailability in legumes, breeding strategies for biofortification of these micronutrients as well as limitations and challenges in breeding programs for biofortification. We have also discussed the evidences from efficacy trials of biofortified beans that will serve as guidepost for future biofortification program. We also highlight the strategic research needed to accelerate the biofortification programs in legumes with a focus on the key challenges such as presence of antinutirents, high throughput-phenotyping, and developing genomic tools.
查看更多>>摘要：? 2022Wheat (Triticum aestivum L.) provides ~ 20% of the calories consumed by a growing global population yet is inherently low in Zinc (Zn) and Iron (Fe). Continued yield gains have inadvertently reduced grain [Zn] and [Fe] (brackets denote concentration, mg kg-1), with negative human health impacts. It is unclear if grain [Fe] or [Zn] of high-yielding modern varieties meet nutritional micronutrient targets. Nitrogen (N) fertilization may synergistically offset yield dilutions and improve grain micronutrients, yet this has not been evaluated in the U.S. Central Great Plains, a region with limited available soil Zn (Znavail). To determine how factors like soil fertility, yield, variety, and fertilization impact grain [Zn] and [Fe], we measured available soil micronutrients and factors that can influence Znavail at six sites in the Central Great Plains. We measured grain yield, protein/N%, and nutrients of three modern wheat varieties grown under two N fertilization regimes. Soil Znavail was critically low at all sites, highlighting the need to re-examine sufficiency guidelines. Grain [Zn] was well below target concentrations at all sites, while grain [Fe] was within 5 mg kg-1 of human nutrition targets. Grain [Zn] declined by ~ 0.8 mg kg-1 for each 1000 kg ha-1 yield, whereas grain [Fe] declined by ~ 2.3 mg kg-1 per 1000 kg ha-1 yield increase, with little varietal difference in yield-adjusted [Zn] and [Fe]. Across sites, N fertilizer only slightly increased grain [Fe] and [Zn] (1.7 and 0.9 mg kg-1, respectively), suggesting that this is not an effective biofortification strategy in these systems. Additional strategies for biofortifying wheat grain [Zn] are required in this region.
查看更多>>摘要：? 2022 Elsevier B.V.Waterlogging is a major ecological threat that restricts crop growth and yield in high rainfall zones across the globe. Waterlogging tolerance is conferred by several complimentary mechanisms, with root cortical aerenchyma (RCA) formation being one of the major ones. In this study, three pairs of near-isogenic lines (NILs) of commercial barley varieties which we introgressed a quantitative trait locus (QTL) for RCA formation, and eight other genotypes contrasting in waterlogging tolerance were subjected to growth under waterlogged and control (non-waterlogged) conditions. Field trials were conducted in 2019 and 2020. The waterlogging treatment began at the two-three leaf stage and continued for two months. The water was subsequently drained, and the crops allowed to recover for final grain yield. Under waterlogging conditions, genotypes with RCA-QTL had significantly higher aerenchyma, white adventitious roots, leaf normalised difference vegetation index (NDVI), higher shoot biomass, tiller number, compared with genotypes without RCA-QTL. Across the three commercial varieties in waterlogged conditions, the average boost to yields from the introgression was 1.8 t/ha. The genotype YF225 showed a degree of waterlogging tolerance but had no RCA-QTL. This appears to be an alternate waterlogging tolerance mechanism that is not yet understood. Importantly, the addition of the RCA-QTL to three commercial varieties showed no significant negative effects on plant growth, yield, and grain quality attributes under control conditions. We conclude that the introgression of an RCA-QTL into other varieties is a promising breeding target for mitigating losses caused by waterlogging.
查看更多>>摘要：? 2022 Elsevier B.V.Rainfed maize (Zea mays L.) crops in low-rainfall regions are cultivated at very low plant population densities that favor the production of fertile tillers or multiple ears in the main shoot. Little information exists regarding the functional processes governing grain yield and kernel setting on ears of different order of shoots of maize crops. To study these functional processes, field experiments were conducted cultivating two commercial maize hybrids (AX7784 and DM2738) under supplementary irrigation using different plant densities, N rates at sowing, shading around female flowering (silking) and tiller removal treatments. Hybrids differed in the number of tillers per plant at R1 (AX7784 > DM2738). Early tiller removal increased main shoot growth rate around silking, suggesting competition for light among shoots. Kernel number per plant was positively and curvilinearly related with plant growth rate around silking, i.e. critical period (PGRCP), in tillered and non-tillered plants of both hybrids. Tillered plants set higher kernel numbers than non-tillered plants at PGRCP > 9 g pl-1 d-1 (AX7784) or 11 g pl-1 d-1 (DM2738), while the opposite trend occurred at PGRCP values < 9 g pl-1 d-1 (both hybrids). In both hybrids, the combination of a higher biomass partitioning to but a lower reproductive efficiency of ears of tillers than of main shoots resulted in a lower kernel number for tillers than for main shoots. Genotypic differences were evident in kernel setting between main shoots (DM2738 > AX7784) and tillers (AX7784 > DM2738). The different pattern of kernel setting between hybrids was explained by differences in the biomass partitioning to tiller ears and the reproductive efficiency of ears of tillers (AX7784 > DM2738), and both the biomass partitioning to and the reproductive efficiency of second and third order ears of main shoots (DM2738 > AX7784). Kernel number per plant was higher for DM2738 due to a higher kernel setting on multiple ears of main shoot plus tillers (more prolific and with lower tiller fertility) than for AX7784 (less prolific and with higher tiller fertility). However, grain yield did not differ between hybrids, because of the higher kernel weight of AX7784. Therefore, this work opens avenues for exploiting higher grain yields in maize crops with low plant population densities through the combination of prolificacy and tillering. Further studies should analyze the impact of reproductive plasticity on kernel weight determination in low-density maize crops.
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