Dry matter production and distribution of zinc in bread and durum wheat genotypes differing in zinc efficiency

Abstract

Six bread wheat (Triticum aestivum cvs. Aroona, and four durum wheat (Triticum durum cvs. BDMM-19, Kunduru-l149, Kiziltan-91 and Durati) genotypes were grown under controlled environmental conditions in nutrient solution for 20 days to study the effect of varied supply of Zn (0 to 1 #M) on Zn deficiency symptoms in shoots, root and shoot dry matter production, and distribution of Zn in roots and shoots.Visual Zn deficiency symptoms, such as whitish-brown lesions on leaves, appeared rapidly and severly in durum wheats, particularly in Kiziltan-91 and Durati. Among the durum wheats, BDMM-19 was less affected by Zn deficiency, and among the bread wheats Kira~-66, ES 91-12, Aroona and Gerek-79 were less affected than ES-14 and Kirkpinar.Under Zn deficiency, shoot dry matter production was decreased in all genotypes, but more distinctly in durum wheat genotypes. Despite severe decreases in shoot growth, root growth of all genotypes was either not affected or even increased by Zn deficiency. Correspondingly, shoot/root dry weight ratios were lower in Zn-deficient than in Zn-sufficient plants, especially in durum wheat genotypes.The distinct differences among the genotypes in sensitivity to Zn deficiency were closely related with the Zn content (Zn accumulation) per shoot but not with the Zn concentration in the shoot dry matter. On average, genotypes with lesser deficiency symptoms contained about 42% more Zn per shoot than genotypes with severe deficiency symptoms. In contrast to shoots, the Zn content in roots did not differ between genotypes. Shoot/root ratios of total Zn content were therefore greater for genotypes with lesser deficiency symptoms than for genotypes with severe deficiency symptoms (i.e. all durum wheat genotypes).The results suggest that the enhanced capacity of genotypes for Zn uptake and translocation from roots to shoot meristems under deficient Zn supply might be the most important factor contributing to Zn efficiency in wheat genotypes. The results also demonstrate that under severe Zn deficiency, Zn concentration in the shoot dry matter is not a suitable parameter for distinguishing wheat genotypes in their sensitivity to Zn deficiency.

Zinc deficiency as a practical problem in plant and human nutrition in Turkey: A NATO-science for stability project

“…Less sensitivity of bread wheats to Zn de®ciency than durum wheats was found to be associated with greater Zn-uptake capacity of bread wheats (Cakmak et al, 1996c;Rengel and Graham, 1996). In a nutrient solution experiment with six bread wheat and four durum wheat cultivars, Zn-de®cient bread wheats had, on average, 29% more Zn accumulation per plant (shoot plus root) than Zn-de®cient durum wheats (Cakmak et al, 1996b).…”

“…In a nutrient solution experiment with six bread wheat and four durum wheat cultivars, Zn-de®cient bread wheats had, on average, 29% more Zn accumulation per plant (shoot plus root) than Zn-de®cient durum wheats (Cakmak et al, 1996b). Interestingly, higher Zn accumulation in bread wheats was pronounced in shoots (42% more Zn per shoot), while roots of durum and bread wheats did not differ in Zn accumulation under Zn de®ciency (Cakmak et al, 1996c). These results indicate that higher Zn ef®ciency of bread wheats compared to durum wheats is related to greater Zn uptake and, particularly, to greater root-to-shoot translocation capacity for Zn.…”

“…In most instances, as noted in Tables 7 and 8, under Zn de®ciency, Zn-ef®cient and Table 7 Zinc-deficiency symptoms (necrotic patches on leaves) and concentration and content of Zn in shoot at the heading state and Zn concentration in grain at maturity in different rye and bread wheat and durum wheat cultivars grown in field on a Zn-deficient calcareous soil (from Cakmak et al, 1996a) Zn-inef®cient lines were not different in amounts of Zn per unit dry weight of leaves and shoots (Graham et al, 1992;Cakmak et al, 1996c). Apparently, Znef®cient lines may contain a larger proportion of Zn that is mobile within the plants and physiologically active in metabolic reactions.…”

“…In terms of root dry matter production, however, wheat genotypes differing in Zn ef®ciency were not distinctly different under Zn de®ciency. Even in nutrient solution experiments, greater sensitivity of durum wheats to Zn de®ciency was associated with greater root growth (Rengel and Graham, 1995a;Cakmak et al, 1996c). However, Zn ef®cient and inef®cient genotypes may differ in root morphology affecting root absorbing surface area (Dong et al, 1995).…”

Characterization of natural variation for zinc, iron and manganese accumulation and zinc exposure response in Brassica rapa L.

“…In China Zn deWciency is prevalent on calcareous soil in North China and calcareous alluvial soils of the Middle and Lower Yangtse River valley (Liu 1994). Breeding and growing of crops with high Zn content and Zn eYciency are promising and sustainable approaches to solve the Zn deWciency problems in humans and soil (Cakmak et al 1996).…”