Abstract
Continuous cropping of rice (Oryza sativa L.) and wheat (Triticum aestivum L.) deplete soil fertility and reduce crop productivity as well as zinc (Zn) concentrations in rice grains and straw. Low Zn concentrations in rice grains have a negative impact on human health, while low Zn concertation in rice straw creates a nutritional problem for animals. The current high yielding rice varieties and hybrids remove large quantities of Zn from the soils, lowering the residual concentrations of soil Zn for the subsequent crop (e.g., wheat). Field experiments were conducted on farmers field in Malakand with the objective to evaluate the impact of various combinations of phosphorus (0, 40, 80, and 120 kg ha−1) and Zn levels (0, 5, 10, and 15 kg ha−1) on biofortification of Zn in grains and straw of rice genotypes [fine (Bamati-385) vs. coarse (Fakhre-e-Malakand and Pukhraj)]. The results revealed that Zn biofortification in rice genotypes increased with the integrated use of both nutrients (P + Zn) when applied at higher rates (80 and 120 kg P ha−1, and 10 and 15 kg Zn ha−1, respectively). The biofortification of Zn in both grains and straw was higher in the coarse than fine rice genotypes (Pukhraj > Fakhre-e-Malakand > Basmati-385). It was concluded from this study that the application of higher P and Zn levels increased Zn contents in rice parts (grains and straw) under the rice-wheat system. We also concluded from this study that Zn concentrations in rice grains and straw are influenced by plant genetic factors and Zn management practices.
Highlights
Rice is the seed of the cereal species Oryza sativa (Asian rice) or Oryza glaberrima (African rice).Rice is the most widely consumed staple food for a large part of the world0 s human population, especially in Asia
We suggested from our study that growing wheat after high-yielding coarse genotypes need more Zn application [5] than that grown after the fine rice genotype
Zinc concentrations in rice grains were significantly affected by P and Zn levels, genotypes, and years (Table 1)
Summary
Rice is the seed of the cereal (grass) species Oryza sativa (Asian rice) or Oryza glaberrima (African rice). Rice is the most widely consumed staple food for a large part of the world0 s human population, especially in Asia. Rice has the third-highest worldwide production (741.5 million t in 2014), after sugarcane (1.9 billion t) and maize (1.0 billion t) [1]. Rice is the staple food crop in the diet of about one-half of the world’s population and provides 35–60% of the dietary calories consumed by nearly more than three billion people [2] and this number will increase to 4.6 billion people by 2050. The current production of rice must increase from 520 million t today to at least 880 million t by 2025.
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