Abstract: Nutrient element content in dropped flower buds，flowers and young fruits as well as the
nutrient losses caused by their drops were studied in Newhall navel orange（Citrus sinensis L. Osb.
‘Newhall’），Okitsu Wase satsuma（Citrus unshiu Marc.‘Okitsu Wase’）and Shatian pomelo（Citrus
grandis Osb.‘Shatian’）adult trees. Results showed that the nutrient element content in flower buds and
flowers of the 3 varieties were N 3.34%–3.66%；P 0.26%–0.31%；K 1.67%–2.30%；Ca，Mg and S
content were 0.17%–0.48%；Fe，Mn，Zn，Cu and B content were 8.1–87.5 mg · kg-1. B content was
significantly higher in flowers than in flower buds，but other nutrient element content in flowers were close
to in flower buds. For the same organs，the content of each nutrient element was slightly different among the 3 varieties. Compared with flower buds and flowers，N and P content in young fruits greatly
decreased and Fe content increased obviously，while the average decreases by 21.8% N and 19.5% P were
measured for the 3 varieties，but the changes of other nutrient element content were not remarkable. The
total dry weight of dropped flower buds，flowers and young fruits was 3 016.3 g per tree for Newhall navel
orange，3 533.6 g per tree for Okitsu Wase satsuma，and 1 486.7 g per tree for Shatian pomelo，which
resulted in serious nutrient element losses of N 49.2–119.4 g，P 4.3–10.1 g，K 30.1–76.2 g，Mg 2.5–7.1
g，Zn 24.0–81.5 mg and B 65.5–170.2 mg for per tree. The losses of nutrient element caused by flower
drops > by flower bud drops > by young fruit drops for Okitsu Wase satsuma and Shatian pomelo，while
caused by flower bud drops were close to by flower drops > by young fruit drops for Newhall navel orange.
Okitsu Wase satsuma had the biggest losses of nutrient element caused by those drops，followed by
Newhall navel orange and Shatian pomelo. Therefore，for citrus management practices，it’s important to
control excessive flowering，and to apply enough fertilizers during spring sprout and blossoms.