MACRONUTRIENT DEFICIENCY SYMPTOMS IN <em>BETULA</em> <em>ALNOIDES</em> SEEDLINGS

Abstract

The decline in seedling quality and production of birch tree (Betula alnoides) is often associated with nutrient stress. Visual foliar symptoms, growth performance, pigment compositions and nutrient interaction of birch seedlings in response to six macronutrient deficiencies were studied. Visual foliar symptoms were most obvious in no nitrogen (-N), no potassium (-K) and no magnesium (-Mg) seedlings but not apparent in no calcium (-Ca) seedlings. Except for -Mg and no sulphur (-S) treatments, seedlings lacking other nutrients showed decreases in most of the growth measurements but an increase in root/shoot ratio. Phosphorous deficiency had no effect on all fractions of pigments, while N and K deficiencies resulted in reductions in chlorophyll-a (chla), chlorophyll-b (chlb), total chlorophyll (chl) and carotenoid (car) but increases in chla/chlb and car/chl ratios. Vector analyses showed that N deficiency not only decreased leaf N concentration but also increased leaf P concentration, possibly because of the antagonism between both ions. Similarly, K, Ca and S deficiencies induced a slight decrease in leaf N concentration that could be explained by a synergism between N and these ions. This kind of nutrient interaction also occurred between P and S in -P seedlings or between Mg and Ca in -Mg seedlings. The findings provided a guideline for diagnosing major macronutrient deficiencies of seedlings. The theoretical foundation for silviculture of B. alnoides will help improve seedling quality and accelerate the sustainable plantation of this species.