Genetic architecture of Grain Iron and Zinc densities and their association with Agronomic traits in Pearl Millet (Pennisetum glaucum (L.) R. Br.)

Micronutrient malnutrition resulting from dietary deficiency of one or more micronutrients has been recognized as a serious human health problem worldwide. The most striking of these are iron (Fe) and zinc (Zn) deficiencies that rank 9th and 11th, respectively, among the top 20 risk factors contributing to global burden of disease. Biofortification is a cost-effective and sustainable agricultural strategy to address the micronutrient deficiencies of resource-poor and majority of malnourished populations. In a recent initiative, research is underway to improve Fe and Zn densities in pearl millet. The main objective of the research reported herein was to study the genetics of Fe and Zn densities and their association with grain yield with a view to enhance breeding efficiency and devise effective breeding strategies for the development of improved cultivars with elevated levels of these micronutrient

Use of infrared thermography imaging for assessing heat tolerance in high and low iron pearl millet lines

In the arid regions of Asia and Africa, pearl millet serves as a staple source of dietary energy and mineral micronutrients for millions of people. These regions are more vulnerable to increased temperature. The availability of rapid and efficient screening tools based on the relevant non-destructive quantifiable traits would facilitate pearl millet improvement for heat tolerance. The objective of this study was to evaluate pearl millet lines with contrast micronutrients for heat tolerance using infrared thermal imaging, a rapid proxy-canopy (panicle and flag leaf) temperature measurement. Results showed the highly significant genotypic differences between high-Fe and low-Fe genotypes for grain Fe and Zn densities and agronomic traits. Both high-Fe and low-Fe group genotypes differed significantly for panicle temperature depression (PTD) during high- vapor deficit (VPD) at stigma stage (3.0 to 6.73°C). PTD values were positive across all genotypes during stigma stage and were very low or negative during the low-VPD. Cooler canopy temperature (high-PTD) was observed during stigma stage rather than seed-set stage at higher-VPD in both high-Fe and low-Fe genotypes. The cooler temperature achieved by panicle might be helpful in maintaining stigma receptivity for longer periods in the female parents, whereas in male parents it might be helpful in maintaining pollen viability for longer periods. Flag leaf temperature (FTD) was cooler than PTD at both high-VPD and low-VPD as well in both stigma (less by 2.1°C) and grain-filling stage (less by 2.7°C), again signifying that the reproductive parts are more prone to heat stress as compared to vegetative parts. Since, thermal imaging discriminates the heat stress and non-stress canopies, this can serve as a proxy canopy temperature tool for heat stress tolerance screening in pearl millet

Maternal inheritance for grain iron and zinc densities in pearl millet

Genetic variation and inheritance of micronutrients in pearl millet has largely been studied in recent years as part of biofortification initiatives. In this study, maternal (reciprocal) effect on inheritance of grain Fe and Zn was studied using a set of diverse breeding material. Entries were paired for low and high for Fe density to produce direct and reciprocal crosses. Over two-seasons, Fe density among parents varied 31-64 mg kg–1 and Zn density varied 28-43 mg kg–1. Difference between each direct and reciprocal crosses for Fe (1 to 4 mg kg–1) and Zn (0 to 2 mg kg–1) were negligible and non-significant, hence cytoplasmic or maternal genes are not likely to modify inheritance of these traits. These results indicate that high Fe/Zn inbred can be used either as female or male parent in hybrid-parent breeding program

Breeding Cultivars for Heat Stress Tolerance in Staple Food Crops

Food and nutritional security will be worsened by climate change-induced high temperatures, droughts and reduced water availability in most agricultural food crops environments, particularly in developing countries. Recent evidences indicate that countries in the southern hemisphere are more vulnerable to food production due to greater frequency of extreme weather events. These challenges can be addressed by: (i) adoption of climate mitigation tools in agricultural and urban activities; (ii) development of heat and drought tolerant cultivars in major food crops; (iii) bringing back forgotten native minor food crops such as millets and root crops; and (iv) continued investment in agricultural research and development with the strong government policy support on native crops grown by small holder farmers. The native crops have inherent potential and traits to cope with adverse climate during the course of its evolution process. Therefore, diversifying the crops should be a prime framework of the climate-smart agriculture to meet the global food and nutritional security for which policy-driven production changes are highly required in developing countries. The adverse effects of climate change on agricultural production need to be addressed by multidisciplinary team and approaches through strong network of research consortium including private sectors and multinational governments for global impact

Genetic variation and diversity for grain iron, zinc, protein and agronomic traits in advanced breeding lines of pearl millet [Pennisetum glaucum (L.) R. Br.] for biofortification breeding

Genetic improvements of iron (Fe) and zinc (Zn) content in pearl millet [Pennisetum glaucum (L.) R. Br.] may reduce the problems of anemia and stunted growth among millet dependent staple food consumers. The availability of variation in diversebreeding lines is essential to improve grain micronutrients in high-yielding cultivars. This study aimed to determine the extent of variability, heritability and diversity for grain Fe, Zn and protein, along with key agronomic traits, in 281 advanced breeding lines bred at ICRISAT and evaluated across two seasons (environments). A pooled analysis of variance displayed significant variation for all these traits. Highest variability was recorded for Fe (35–116 mg kg-1), Zn (21–80 mg kg-1), and protein (6–18%), and a three-fold variation was observed for panicle length, panicle girth and 1000-grain-weight (TGW). Diversity analysis showed 10 clusters. Cluster-III had maximum lines (25%) and Cluster-V showed the highest mean values for Fe, Zn, protein and TGW. These results highlight the success of breeding program that aimed both the maintenance and creation of genetic variability and diversity. A significant positive correlation among Fe, Zn, protein and TGW indicated the potential for simultaneous improvement. Grain yield had a non-significant association with Fe and Zn, while protein showed a negative correlation. These results suggest that significant variability exists in elite-breeding lines, thus highlighting an opportunity to breed for biofortified varieties without compromising on the grain yield. The lines with high Fe, Zn and protein content can be used as hybrid parents and may also help in further genetic investigations

Effect of isogenic-alloplasmic cytoplasmic male sterility system on grain yield traits in pearl millet

Pearl millet is a nutri-cereal and is grown predominantly by subsistence farmers in semi-arid regions of India and Africa. Considering highly cross pollination nature and availability of cytoplasmic male sterility (CMS), pearl millet hybrids are becoming a dominant cultivar type in India. Present study aims to assess the effect of isonucleus-alloplasmic, A1, A4 and A5 cytoplasmic male sterility system on agronomic performance of pearl millet hybrids. Five isogenic females each having 3 alloplasmic (A1, A4 and A5) cytoplasm were crossed with 6 male-parents to generate 120 hybrids and were evaluated in two contrasting season in splitsplit- plot design (SSPD). The significant cytoplasm per se and restorer per se indicate the both contribution to most of the traits, however, greater magnitude of contribution arises from restorers (74% grain yield; 95% 1000-grain weight). The significant hybrids × environment shows the mandatory of multi location testing for yield traits while non-significant of CMS × environment interactions reveals the greater stability of CMS. Further, no significant mean yield differences exhibited in A1, A4 and A5 hybrids (2.53-2.81 t ha-1) indicates not any adverse effect of cytoplasm on grain yield and associated traits. Also, diverse genetic backgrounds used in this study exhibited significant contributions to grain yield and its component traits. These results imply the prospects for utilization of potential alternative cytoplasm (A4 and A5) to widen the cytoplasm base together with development of counterpart restorers to produce future high-yielding hybrids

Genetic diversity analysis among advanced breeding lines in pearl millet for grain iron, zinc and agronomic traits

Evaluation of genetic diversity within breeding populations will help in parents’ diversification and identification of trait-specific inbred sources. Total of 294 inbreds were evaluated for grain iron (Fe), zinc (Zn) and agronomic traits in two contrasting seasons using alpha-lattice field design. There was a significant variability observed for all traits. Three-to-four-fold variability noticed for Fe (31-120 mg kg-1), Zn (19-88 mg kg-1), yield (0.6-2.6 tha-1) and 1000- grain weight (6-16 g 1000-1). The magnitude of genetic coefficient of variation explained by traits were varied in the order of Fe (25%)>Zn>TGW>PL>PH>GY>PG>DF (7%) and heritability (broad sense) was very high as >84% for all traits except grain yield (56%). Nine clusters formed at 90% genetic similarity. Clusters I to IV and VII had higher mean value for Fe density (78-100 mg kg-1) and agronomic traits. Highest number of genotypes grouped in cluster I (63) followed by cluster III (54) having higher yield,1000-grain weight, panicle girth, Fe and Zn. Top-10% of high-Fe lines had significantly higher Fe (64%), Zn (49%), grainweight (29%) and panicle girth (19%) than bottom-10% genotypes. This implies that high- Fe/Zn sources are available with eliteness and can be incorporated into any genetic background without compromising agronomic superiority. Higher heritability and genetic advance as percentage of mean were observed for Fe, Zn and grain-weight suggesting these traits are predominantly determined by additive gene and can be improved through selection

Does Soil Micronutrient Variability in Test Locations Influence Performance of Biofortified Pearl Millet in India?

Testing of biofortified hybrids across varying pearl millet-growing regions of India indicated the need for maintaining sufficient Fe and Zn levels in soil to express the crops’s full genetic potential and ensure successful loading of micronutrients in the grain. The study suggested the need for practicing balanced fertilization while growing biofortified hybrids to increase grain yield and micronutrient accumulation in grains

Genetic Variability, Diversity and Interrelationship for Twelve Grain Minerals in 122 Commercial Pearl Millet Cultivars in India

Pearl millet contributes to the major source of dietary calories and essential micronutrients intake among rural populations in certain regions of India as its grains are more nutritious than other cereals. The aims of this investigation were to profile cultivar nutrition, diversity and interrelationship for grain minerals (Ca, K, Mg, Na, P, S, Cu, Fe, Mn, Zn, Mo and Ni) among 122 pearl millet hybrids and open-pollinated varieties in India. Trials were evaluated in randomized complete block design with three replications at two locations (Patancheru and Mandor) representing two major cultivation zones. The grain minerals in cultivars exhibited two- to- four-fold variation. Positive and significant correlations were noted among different minerals. A higher magnitude of positive and significant association between Fe and Zn (r = 0.71, P\0.01) and with other minerals suggested the existence of greater genetic potential for the concurrent improvement of Fe and Zn without lowering the other grain minerals in pearl millet. The first two principal components accounted for 49% of variation. Euclidian distancebased cluster analysis grouped the 122 cultivars into seven clusters. Cluster I had higher mean for Fe (56 mg kg-1) and Zn (49 mg kg-1), in which ICTP 8203, Ajeet 38, Sanjivani 222,PAC 903 and 86 M86 were identified as rich sources of iron, zinc and calcium with considerable levels of other nutrients. About 65% of cultivars for iron and 100% of cultivars for zinc have met the minimum standards set forth by the Indian Council of Agricultural Research. This indicates the feasibility of breeding nutrient-rich hybrids with competitive yields through mainstreaming in future

Breeding Biofortified Pearl Millet Cultivars Unlock Millet Markets for Nutrition

Pearl millet is an important food crop in the arid and semi-arid tropical regions o f Afri ca and Asia. These regions are home to millions of poor smallholder's households living in harsh agro ecology and reported higher prevalence of malnutrition. Such poor households have few options in terms of food crops, besides the limited markets. Indeed, pearl millet is one of the food crops they continue to grow for their food and nutritional security. Pearl millet is important sources of dietary carbohydrates, energy, protein, and important minerals such as calcium, iron and zinc. Conside ring inherent high nutritional values and climate resilient nature (drought and heat), demand for pearl millet as food, beside valued for its Stover as a source of livestock fodder, is projected to g row strongly in Asia (India) and Africa (West and Central Afri ca). Iron (cause anemia) and zinc (cause stunting) deficiencies are widespread and serious publ ic heal th problems worldwide, including Lndia and Africa. Biofortification is a cost-effective and su stainable agricultural strategy to address this problem. Research on pearl millet has shown that large genetic variability (30-140 mg!kg Fe and 20-90 mg! kg Zn) ava ilable in this crop ca n be effectively utilized to develop high-yield in g cul tiva rs with high iron and zinc densities. Both Open - pollinated varieties (Dhanshakti and Chakti ) and hybrids (ICMH 1202, ICMH 1203 and ICMH 1301) of pea rl millet with high grain yield (>3.5 tons/ha in hybrids) and high levels of iron (70-75 mg/kg) and zinc (35-40 mg/kg) densities have been developed and released. Currently, India growing >70,000 ha of biofortified pearl millet, besides more pipeline hybrids and varieties are under various stage of testing at the national (India) and international (west Africa) trials for possible release. Genomic tools will be an integral part of breeding program particularly for nutritional traits to use diagnostic markers and genomic selection. Clinical studies showed that 200g grains from biofortified culti var would provide bioavailable Fe to meet full recommended daily allowance (RDA) in children, adult men and 80% of the RDA in women. Till today, no markets to promote biofortified cultivars/grains/products as no incentive price and such products aims to address food and nutri tional securi ty challenges simultaneously. The demand is likely to increase only after investment and integration into modern public d istribution system, nutritional intervention schemes, private seed and food companies with strong mainstreaming nutritional policies. In the non-traditional regions, this will contribute to livestock and poultry feed industry as spill-over benefi ts to improve nutrition