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In wheat and other grain species, variations in kernel size are related to variations in ovary size. It is not known whether environmental factors that are known to affect kernel size may also affect ovary size, thus maintaining the kernel size‐ovary size correlation. Additionally, it is not known whether variations in ovary size in wheat depend on cell size, cell number or both. In this study, ovary size was measured with a stereomicroscope, and ovary wall cell size and number were measured in equatorial cross‐sectional areas of the ovary wall in two common wheat cultivars with different kernel size: Bora (large kernels) and Bologna (small kernels). Plants were grown at low and high N fertilization (0 and 240 kg ha−1) with normal density (450 seeds m−2), and at low and high plant density (200 and 650 plants m−2) with normal fertilization (160 kg N ha−1). The variation in ovary wall size across all data pooled (i.e., including two genotypes, two N and two density treatments, and including within treatment variations), was related to cell number and not to the cell size, which did not vary significantly with cultivar and field practices. With increasing ovule size, ovary wall size increased less than proportionally, thus the ovule/ovary ratio increased. Cell size in the ovary wall showed an upper limit across all treatments, which decreased with increasing cell number. These findings may be useful for breeding programs and field practices aimed at increasing kernel size and yield.

Many works carried out in the last decades have shown that the pollen season for taxa flowering in winter and spring, in temperate regions, has tended to be earlier, probably due to the continuous rise in temperature. The mean annual temperature in Perugia, Central Italy, was about 0.5 °C higher in the last three decades compared with that registered from 1952 to 1981. The increase of temperature took place mainly in winter and spring, while no significant variation was recorded during the summer and autumn. This scenario shows variations in the timing and behavior of flowering of many spontaneous plants such as grasses, whose phenology is strongly influenced by air temperature. This work reports fluctuations in the airborne grass pollen presence in Perugia over a 33-year period (1982-2014), in order to study the influence of the warming registered in recent years on the behavior of pollen release of this taxon. The grass pollen season in Perugia typically lasts from the beginning of May to late July. The start dates showed a marked trend to an earlier beginning of the season (-0.4 day/year), as well as a strong correlation with the average temperatures of March and April. The peak is reached around 30th May, but the annual pollen index (API) is following a decreasing trend. The correlation between starting dates and spring temperatures could be interesting for the constitution of a forecasting model capable of predicting the presence of airborne grass pollen, helping to plan therapies for allergic people.

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