Optima 5300 dv instrument

Plant growth was assessed as plant height, number of tillers (Table 2), total biomass, grain quantity, 1000 grain weight, grain yield and nutrient concentration from shoot and grains. The number of generative tillers was counted just before flowering. Shoot and root fresh and dry weights were measured at tillering (7 weeks) and at maturity (12 weeks). Shoots were dried at 70°C in a forced-air oven for at least 72 h, weighed and finely ground. N was assessed using combustion analysis in an Elementar (vario Marco CNS; Elementar, Germany). Subsamples were digested in 5:0.5 HNO₃-HClO₄ (Simmons, 1975 (link), 1978 (link)). P and K were measured using a Perkin Elmer Optima 5300dv instrument. Shoot N, P and K uptake were calculated as the product of shoot dry mass yield and the concentration of individual macro-element.
The number of grains per ear was determined at maturity and 1000 grain weight was calculated (Table 2). Harvest index was calculated as the dry matter of grain yield divided by the sum of dry matter of grain yield and straw yield (Metho and Hammes, 2000 (link)). Wheat grains were ground prior to chemical analysis, and N, P and K uptake in grains were calculated as the product of grain dry mass yield and the concentration of individual macro-element.

Frozen samples of LVW, RVW, and VS were weighed and transferred into polypropylene vials for analysis. After freeze-drying to constant weight, the dried tissues were again weighed prior to digestion at atmospheric pressure with double-distilled concentrated nitric acid in a microwave-assisted reaction system (CEM Corporation, Matthews, NC, USA). Acid digests were diluted 8-fold with deionized water and analyzed for Fe and Zn by inductively coupled plasma-optical emission spectrometry (ICP-OES), using a Perkin Elmer Optima 5300 DV instrument (Shelton, CT, USA). The analytes were measured at the respective wavelengths of 259.939 nm for Fe and 213.857 nm for Zn. Standard solutions were prepared from pure single metal stock solutions (purity of 99.999%; High Purity Standards, Charleston, SC, USA). The ICP-OES method was validated through the analysis of certified reference materials as described previously [9 ]. Results were calculated as μg metal/g dry weight and converted to μg/g wet weight based on the frozen water content.