*3.1. Grain Yield*

When comparing the common and spelt wheat yields, statistically significant di fferences were found for each N-fertilisation levels, though the di fference was only marginal in favour of common wheat at N40 with a significance of *p* = 0.031. When pooling together the N0 and N40 yields for the three years spelt wheat had significantly higher production (*p* = 0.033) having 0.24 t ha−<sup>1</sup> higher average yield at this, low fertilisation level. At moderate fertilisation level (N80 and N120 together) common wheat had 1.14 t ha−<sup>1</sup> higher average yield that is a significant (*p* ≈ 0) surplus compared to spelt. This result confirms that spelt wheat is a real alternative to common wheat for low input production [10] even for sites with fertile soils. Both common wheat and spelt had the highest yield under the maximal N dose in 2019, despite the fact that this was the driest experimental year. The high yield might be the result of the large amount of precipitation in May (~140 mm), that was ~82% higher than the multi-year average of that month. This underlines the importance of timing of the precipitation that might be an even more important factor in yield formation than the precipitation amount in certain years.

**Figure 2.** Harvested grain yield (t ha−1), LAImax (m<sup>2</sup> m<sup>−</sup>2) and chlorophyll content (mg m<sup>−</sup>2) of spelt (*T. spelta*) and common wheat (*T. aestivum*) across varieties under four di fferent nitrogen fertilisation treatments (0, 40, 80 and 120 kgN ha−1) at Martonvásár (Hungary) in 2016, 2018 and 2019. \* indicates statistically significant di fference between spelt and common wheat.

The N-fertilisation significantly affected the grain yield (Figure 2) with a positive correlation between the N amount and the yield except for spelt in 2016. In 2016, high winds in June caused considerable lodging of growing degree with the increasing N fertilisation levels: 20, 45, 55 and 65% lodging at the N0, N40, N80 and N120 levels, respectively. Lodging made it very difficult for the harvester to properly harvest the plots resulting in uncertain and reduced yield results. In line with previous studies it is evident that lodging is clearly an issue in spelt production especially at higher N levels [35,36]. Common wheat showed much stronger reaction to the increasing fertiliser doses. Each increment in the N dose resulted in significantly higher yields. The N120 common wheat yields were 31–61% higher than that of the N0 yields. Even after excluding the 2016 data from the *t*-tests because of the lodging issue, spelt showed 8–9% yield increase when the N120 yields were compared to the N0 yields when yield averaged across 2018 and 2019. This is a moderate fertiliser effect, though statistically significant (*p* = 0.0068). There was a significant yield increase between the N0 and N40 levels (*p* = 0.0092) but the further N increments were not associated with further significant yield growth. According to this result spelt wheat can close in its yield potential even at very low fertiliser levels (approx. 40 kgN ha−<sup>1</sup> y<sup>−</sup>1) on fertile soils. The variety selection had significant effect on the yield of both crops. Regarding the averaged N-treatments across the years, Mv Marsall, a common wheat variety had the highest yield (6.09 t ha−1) that was significantly higher than the average yields of the other two common wheat varieties. Mv Martongold and Mv Vitalgold spelt wheat varieties provided the highest average yields (5.37 and 5.3 t ha−1) that were significantly higher than the average yield of the Franckenkorn variety.
