Zn deficiency is one of the leading health problems in children and women of developing countries. Different interventions could be used to overcome malnutrition, but biofortification is most impactful, convenient, sustainable and acceptable intervention. Maize is one of the major crops grown and consumed in the regions with prevalent Zn malnutrition; therefore, this is suitable target for Zn biofortification. Zn biofortification of maize could be achieved through agronomic and genetic approaches. Discussion of agronomic approaches with genetic approaches is prerequisite because soils in developing countries are deficit of Zn and availability of Zn in soils is mandatory for estimating the genetic responses of maize genotypes through genetic approaches. Seed priming, foliar and soil applications are agronomic tools for biofortification, but solo and combined applications of these treatments have different effects on Zn enrichment. Genetic approaches include the increase of Zn bioavailability or increase of kernel Zn concentration. Zn bioavailability could be increased by reducing the anti‐nutritional factors or by increasing the bioavailability enhancers. Kernel Zn concentration could be improved through hybridization and selections, whereas genetically engineered attempts for improving Zn uptake from soil, loading in xylem, remobilization in grains and sequestration in endosperm can further improve the kernel Zn concentration. Key challenges associated with dissemination of Zn biofortified maize are also under discussion in this draft. Current review emphasized all of above‐mentioned contents to provide roadmap for the development of Zn biofortified maize genotypes to curb the global Zn malnutrition.

Vitamin A deficiency is widely prevailing in children and women of developing countries. Deficiency of vitamin A causes night blindness, growth retardation, xerophthalmia and increases the susceptibility against epidemic diseases. Among different interventions of overcoming malnutrition, biofortification is the most acceptable and preferred intervention among researchers, growers and consumers. Maize is grown and consumed in those regions where vitamin A deficiency is most prevalent; thus, targeting this crop for provitamin A biofortification is the most appropriate solution.Different breeding strategies including diversity analysis, introduction and stability analysis of exotic germplasm, hybridization, heterosis breeding, mutagenesis and marker-assisted selection are practised for exploring maize germplasm and development of provitamin A-enriched cultivars. Genome-wide association selection and development of transgenic maize genotypes are also being practised, whereas RNA interference and genome editing tools could also be used as potential strategies for provitamin A biofortification of maize genotypes. The use of these breeding strategies for provitamin A biofortification of maize is comprehensively reviewed to provide a working outline for maize breeders. Retinol activity equivalent (RAE) is the best option to express the dietary reference intake (DRI) of vitamin A because bioavailability is accounted in this way. Recommended DRI for females is usually 700 RAE, for pregnant females 770 RAE, for lactating females 1,200-1,300 RAE, for children 400-500 RAE and for males 900 RAE. One

Haploids are naturally produced in maize (Zea mays L.) at different rates and can also be induced through different methods. Haploids are used to develop doubled haploids (DHs), which have many potential uses. The development of DH lines in maize involves haploid induction, haploid identification, chromosome doubling, and field sowing for self‐pollination of D0 plants. Different potential methods are used for haploid induction, in‐vivo maternal haploid induction being the most prevalent. Haploid induction is highly reliant on the unambiguous identification of haploids among a mixture of different ploidies. Haploid identification is facilitated by visual morphological markers, chromosome counting, flow cytometry, molecular markers, and many other approaches. Chromosome doubling may be achieved by spontaneous doubling or by induction with different antimicrotubular treatments. Among the potential uses of DH lines are the development of inbred lines, genomic selection (GS), quantitative trait loci (QTL) mapping, and unlocking new genetic variations. Although DH technology can potentially accelerate maize breeding, it still faces challenges at each step of DH line development. This article aims to highlight the importance, procedural steps, potential opportunities, and key challenges in DH line development in maize.

Maize germplasm was exclusively collected across Pakistan to probe the trends in genetic variability at regional levels and chronological periods. A total of 290 accessions were collected from 6 different regions. These were comprised of the following chronological order:

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Zinc deficiency affects one third of the population worldwide, and vitamin A deficiency is a prevalent public health issue in Sub-Saharan Africa and South-Asia, including Nepal. Crop biofortification is the sustainable solution to these health—related problems, thus we conducted two different field trials in an alpha lattice design to identify zinc and provitamin A biofortified maize genotypes consistent and competitive in performance over the contrasting seasons (Season 1: 18 February to 6 July 2020 and Season 2: 31 August to 1 February 2020/21). In our study, the performance of introduced maize genotypes (zinc—15 and provitamin A biofortified—24) were compared with that of the local check, focusing on the overall agro-morphology, yield attributes, yield, and kernel zinc and total carotenoid content. Zinc and total carotenoid in the tested genotypes were found in the range between 14.2 and 24.8 mg kg−1 and between 1.8 and 3.6 mg 100 g−1. Genotypes A1831-8 from zinc and EEPVAH-46 from provitamin A biofortified maize trial recorded kernel zinc and total carotenoid as high as 52.3, and 79.5%, respectively, compared to the local check (DMH849). The provitamin A genotypes EEPVAH-46 and EEPVAH-51 (total carotenoid: 3.6 and 3.3 mg 100 g−1), and zinc biofortified genotypes A1847-10 and A1803-42 (20.4 and 22.4 mg kg−1 zinc) were identified as superior genotypes based on their yield consistency over the environments and higher provitamin A and zinc content compared to the check. In addition, farmers can explore August sowing to harvest green cobs during December-January to boost up the emerging green cob business.

Maize (Zea mays L.) is short duration, high yielding crop, and it can be grown in both spring and kharif seasons in Pakistan. In current study white and yellow maize germplasms were compared for correlations and genetic variability based on different agronomic traits to define selection criteria for maize improvement. Significant differences were observed for yield and related components for entries, checks, all tested genotypes, yellow and white germplasm. Yellow maize genotypes showed higher yield potential compared to white maize genotypes because of more grains per row and number of rows per cob. Based on correlation and path coefficient analysis, yield per plant was proved as appropriate selection criteria for white maize whereas, yield per plant and grains per row were suitable selection criteria for genetic improvement of yellow maize. Total carotenoid contents of yellow maize were independent of the yield so, both can be simultaneously targeted for genetic improvement without paying yield penalty. However, further dissection of genetic variability in yellow maize germplasm based on provitamin A carotenoids is prerequisite. So, far as genotypes, 19189, 15159, 19201, 15018, 15216, 15170, 15155, 19196, 15318 and 19174 among white maize germplasm whereas, 14965, 14982, 19205, 15019, 14971, 15163, 15205, 24687, 15207 and 15194 among yellow maize germplasm were the potential high yielding genotypes. Findings of the study in terms of selection criteria and potential maize genotypes could be useful in different breeding programs for genetic improvement of maize