Genotypic variation for productivity, zinc utilization efficiencies, and kernel quality in aromatic rices under low available zinc conditions

Zinc (Zn) has emerged as the plant nutrient limiting rice growth in several parts of the world. About 50% of world soils are deficient in Zn and this is also true for India. An analysis of 0.233 million samples taken from different states showed that 47% of Indian soils are deficient in Zn. In India, Zn deficiency is widespread, especially in the rice-wheat cropping system belt of North India, which has high pH calcareous soils. Zinc is also now recognized as the fifth leading health risk factor is developing Asian countries, where rice is the staple food and Zn nutrition of humans and animals has recently received considerable attention. However, no reports are available on the effect of Zn fertilization on kernel quality of aromatic rices. The present study was therefore undertaken to study the effect of Zn fertilization on yield attributes, grain, and straw yield, Zn concentrations in grain and straw, Zn uptake, Zn use indices and kernel qualities of the aromatic rices. A field study at the Indian Agricultural Research Institute, New Delhi, India showed that Pusa Sugandh 4 ('PS 4') is a better than the earlier developed aromatic rice variety Pusa Basmati 1 ('PB 1') in terms of grain yield (4.08 tonnes ha-1), kernel quality, zinc (Zn) concentrations in grain and Zn uptake (1,396.9 g ha-1), recovery efficiency (5.2%), agronomic efficiency (122.7 kg grain increase kg-1 Zn applied), partial factor productivity (1,064.7 kg grain kg-1 Zn applied) and physiological efficiency (39,625 kg grain kg-1 Zn uptake) of applied Zn. From the grain yield (4.64 tonnes ha-1) viewpoint an application of 5 kg Zn ha-1 was found sufficient for the aromatic rices grown on ustochrepts of north Indian rice-wheat cropping system belt. Application of 7.5 kg Zn ha-1 increased Zn concentrations in the grain (37.0 mg kg-1 DM) and straw (117.3 mg kg-1 DM) of aromatic rices studied and this is important from the human and animal nutrition viewpoint under Indian conditions.