The use of black leaf-clips for dark adaptation under high solar radiation conditions is reported to underestimate the maximum quantum yield of PSII photochemistry (Fv/Fm) measured by the continuous-excitation fluorometer Pocket PEA. The decrease in Fv/Fm was due to a rise in minimum fluorescence emission (F0), probably resulting from increased leaf temperature (Tl). In
field-grown tomato and pepper, fluorescence parameters and Tl in the region covered by the black leaf clip were measured in clipped leaves exposed to solar radiation during dark adaptation (clipped-only leaves) and in clipped leaves protected from solar radiation by aluminium foil (shrouded clipped leaves). Results confirmed significant Fv/Fm underestimates in clipped-only leaves primarily due to increased F0. In one tomato experiment, Tl increased from 30 to 44.5°C in clipped-only leaves, with a negligible rise in shrouded clipped leaves. In two respective pepper experiments, Tl in clipped-only leaves increased from 27 to 36.2°C and 33 to 40.9°C. Based on the results of this study, a clip-effect parameter (PCE) on fluorescence emission is proposed as the difference for Fv/Fm (or -F0/Fm) between shrouded clipped leaves and clipped-only leaves, which resulted to be 0.706 for tomato, and 0.241 and 0.358 for the two pepper experiments., P. Giorio ... [et al.]., and Obsahuje bibliografii
There is very little information on the importance of fleshy fruit in the diet of the nestlings and fledglings of partially frugivorous Holarctic passerines. In an area of 0.6 km2 in northwestern Spain, it was verified during 2001–2003 that at least one blackcap Sylvia atricapilla pair and five blackbird Turdus merula pairs fed their offspring on a certain proportion of ivy Hedera helix fruit. Observations made on a blackcap nest in May showed that the parents fed older nestlings on animal prey on 60.7% of occasions and 39.3% on fruit (n = 140 total number of identified feeds). The female fed nestlings on fruit more often than the male. According to observations carried out on five ivy plants in May, blackcaps brought fruit in their bills to feed nestlings or fledglings on 40.3% of 67 feeding visits and blackbirds on at least 22.1% of 86 feeding visits. The blackcaps consistently carried one fruit and the blackbirds between three and five. Both species fed their young on fruit under very different meteorological conditions. Seeds found in the faecal sacs of their nestlings showed high potential germination viability (95.6% undamaged seeds and 4.4% cracked seeds; n = 46 total seeds except for those gnawed by rodents), so the adults probably acted as indirect vectors in dispersing ivy whilst carrying faecal sacs away from the nest.