A review of existing and proposed new leaf nutrient standards for lychee

Abstract

The most recently matured leaf behind the vegetative flush or fruiting cluster (flowering trees) was sampled monthly over 3 years from seven lychee orchards (Litchi chinensis Sonn. cultivars ‘Tai So’ ‘Haak Yip’ and ‘Wai Chee’) in subtropical Australia (Lat. 27°S). The concentrations of most nutrients were stable from the maturation of the late summer/early autumn vegetative flush of growth to panicle emergence or just after in winter (May–August). The choice of sample would influence the diagnosis for N, K, Ca, Fe and B at these orchards because of the effect of season on leaf nutrient concentrations. It is recommended that lychee leaves be sampled for diagnostic purposes from flowering branches 1–2 weeks after panicle emergence. Tentative standard leaf levels for Australian lychee orchards after panicle emergence during May–August are: 1.50–1.80% for N, 0.14–0.22% for P, 0.70–1.10% for K, 0.60–1.00% for Ca, 0.30–0.50% for Mg, 50–100 μg g−1 for Fe, 100–250 μg g−1 for Mn, 15–30 μg g−1 for Zn, 10–25 μg g−1 for Cu, 25–60 μg g−1 for B, <500 μg g−1 for Na and <0.25% for Cl.