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Grain Zinc and Iron Association Studies in Swarna X Type 3 RIL Population of Rice

Rice is a staple food for millions of people and having great importance in food and nutritional security. Rice is the second most widely consumed cereal in the world next to wheat. From poorest to richest person in this world consume rice in one or other form. In the last two decades, new research findings generated by the nutritionists have brought to light the importance of micronutrients, vitamins and proteins in maintaining good health, adequate growth and even acceptable levels of cognitive ability apart from the problem of protein energy malnutrition. Biofortification is a genetic approach which aims at biological and genetic enrichment of food stuffs with vital nutrients (vitamins, minerals and proteins). Ideally, once rice is biofortified with vital nutrients, the farmer can grow indefinitely without any additional input to produce nutrient packed rice grains in a sustainable way. This is also the only feasible way of reaching the malnourished population International Journal of Current Microbiology and Applied Sciences ISSN: 2319-7706 Volume 7 Number 05 (2018) Journal homepage: http://www.ijcmas.com


Introduction
Rice is a staple food for millions of people and having great importance in food and nutritional security. Rice is the second most widely consumed cereal in the world next to wheat. From poorest to richest person in this world consume rice in one or other form. In the last two decades, new research findings generated by the nutritionists have brought to light the importance of micronutrients, vitamins and proteins in maintaining good health, adequate growth and even acceptable levels of cognitive ability apart from the problem of protein energy malnutrition. Biofortification is a genetic approach which aims at biological and genetic enrichment of food stuffs with vital nutrients (vitamins, minerals and proteins). Ideally, once rice is biofortified with vital nutrients, the farmer can grow indefinitely without any additional input to produce nutrient packed rice grains in a sustainable way. This is also the only feasible way of reaching the malnourished population The present study was undertaken with the objective to determine the degree of association between yield, yield attributing traits and grain Zinc and Iron concentration in Swarna x Type 3 RIL population of rice. 100 RIL population were evaluated for identifying their efficiency with respect to ten characters. The correlation studies revealed that grain yield per plant showed strong positive significant association with plant height and 1000seed weight. Positive non-significant association of grain yield per plant was observed with days to 50 per cent flowering, panicle length, number of filled grains per panicle and significant negative correlation was observed for grain iron and zinc concentration.
in India. In this context breeders are now focusing on breeding for nutritional enhancement to overcome the problem of malnutrition.
The range of iron and zinc concentration in brown rice is 6.3-24.4 μg/g and 13.5-28.4 μg/g respectively. There is approximately a fourfold difference in iron and zinc concentration, suggesting some genetic potential to increase the concentration of these micronutrients in rice grains.
A scarce scientific literature is available on the association between grain iron and zinc content with grain yield. The present research was taken up to study the association of grain iron and zinc with grain yield.

Materials and Methods
The experiment was conducted at Indian Institute of Rice Research Farm, Ramachandrapuram, Hyderabad, India, during kharif, 2017. The experimental material comprised of 100 RILs of F 7 population derived from Swarna and Type 3 along with four checks (Swarna, Type 3, BPT 5204, Chittimutyalu) laid out in Augmented Block Design. All the recommended package of practices was followed along with necessary prophylactic plant protection measures to raise a good crop.
Five representative plants for each population were randomly selected to record observations on the quantitative characters under study. Data on days to 50% flowering (DFF) recorded at flowering stage while, plant height (PH), panicle length (PL), number of productive tillers per plant (NPT) were recorded at harvest and panicle weight, number of filled grains per panicle (FGP), test-weight (TW), grain iron content (Fe), grain zinc content (Zn) and grain yield per plant (GY) were recorded after harvest. Grain Iron and Zinc content were estimated by following recommended standard procedure i.e., X -Ray fluorescence Spectrometry (XRF).

Statistical analysis
Simple correlation coefficients were calculated for grain yield and its components using the formulae given by Webber and Moorthy (1952).

Results and Discussion
Grain yield is a complex character and is dependent on its contributing traits. The study was envisaged on character association, to assess the relationships among yield and its components and to have an insight into the causes for higher yield in hybrids and varieties. Simple correlations were worked out on yield and yield contributing characters in 100 RIL population of rice (Table 1).

Grain zinc concentration
Grain zinc concentration showed a negative significant correlation with grain yield per plant (-0.4243**), and positive significant correlation with grain iron content (0.6691**). The results were in accordance with Nagesh et al., (2013) for grain yield per plant and Gangashetty et al., (2013) and Nagesh et al., (2013) for grain iron concentration.

Grain iron concentration
Grain Iron concentration showed a negative significant correlation with grain yield per plant (-0.4059**), significant positive correlation with grain zinc concentration (0.6691**). Similar findings were reported by Nagesh et al., (2013) for grain yield per plant and Gangashetty et al., (2013) and Nagesh et al., (2013) for grain iron concentration.
The present study has revealed that grain yield had strong positive significant association with plant height and 1000-seed weight. Grain iron content and zinc content had no correlation with grain yield. Simultaneous selection / breeding can be taken up to enhance grain iron and zinc and grain yield because of absence of correlation.