Journal of Tropical Forest Science 22(4): 403–413 (2010) Chen L et al. MACRONUTRIENT DEFICIENCY SYMPTOMS IN BETULA ALNOIDES SEEDLINGS L Chen1, 2, J Zeng1, *, DP Xu1, ZG Zhao1 & JJ Guo1 1Research Institute of Tropical Forestry, Chinese Academy of Forestry, Longdong, Guangzhou 510520, PR China 2Experimental Center of Tropical Forestry, Chinese Academy of Forestry, PingXiang, GuangXi 532600, PR China Received October 2009 CHEN L, ZENG J, XU DP, ZHAO ZG & GUO JJ. 2010. Macronutrient deficiency in symptomsBetula alnoides seedlings. 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 ofB. alnoides will help improve seedling quality and accelerate the sustainable plantation of this species. Keywords: Foliar symptom, growth performance, nutrient interaction, pigment composition CHEN L, ZENG J, XU DP, ZHAO ZG & GUO JJ. 2010. Gejala kekurangan makronutrien dalam anak benih Betula alnoides. Kemerosotan kualiti anak benih pokok birch (Betula alnoides) dan penghasilan pokok birch kerap dikaitkan dengan tegasan nutrien. Gejala daun yang dapat dilihat, prestasi pertumbuhan, komposisi pigmen dan interaksi nutrien anak benih pokok birch terhadap kekurangan enam makronutrien dikaji. Gejala daun paling ketara pada anak benih tanpa nitrogen (N), tanpa kalium (K) dan tanpa magnesium (Mg) tetapi tidak jelas pada anak benih tanpa kalsium (Ca). Anak benih yang kekurangan nutrien lain kecuali Mg dan sulfur (S) menunjukkan penurunan dalam kebanyakan parameter pertumbuhan. Namun, nisbah akar/pucuk menunjukkan peningkatan. Kekurangan P tidak mempengaruhi komposisi pigmen. Kekurangan N dan K mengakibatkan penurunan dalam kandungan klorofil a (chla), klorofil b (chlb), jumlah klorofil (chl) dan karotenoid (car) tetapi peningkatan dalam nisbah chla/chlb serta car/chl. Analisis vektor menunjukkan bahawa kekurangan N bukan sahaja mengakibatkan penurunan kepekatan N daun tetapi juga peningkatan kepekatan P daun. Ini menunjukkan kemungkinan berlakunya antagonisme antara kedua- dua ion. Kekurangan K, Ca and S menyebabkan sedikit penurunan dalam kepekatan N daun yang mungkin diakibatkan oleh synergisme antara N dengan ion-ion tersebut. Interaksi nutrien sedemikian juga berlaku antara P dengan S dalam anak benih tiada P atau antara Mg dengan Ca dalam anak benih tiada Mg. Kajian ini menyediakan garis panduan untuk mengenal pasti kekurangan makronutrien yang utama dalam anak benih. Teori asas tentang silvikultur B. alnoides boleh menambah baik kualiti anak benih dan mempercepat penanamannya secara mapan di ladang. INTRODUCTION Soil and water loss has been increasing in K and Mg (Macleod et al. 2004). A consequence most areas of south China over the last two is a substantial decrease in forest quality and decades due to excessive deforestation and production, particularly for plantation species. heavy vegetation disturbance. This results in While the nutrient availability of sites influences serious nutrient poverty of soils, especially N, P, growth of trees in plantations, the nutrient *Author for correspondence. E-mail: [email protected] © Forest Research Institute Malaysia 403 Journal of Tropical Forest Science 22(4): 403–413 (2010) Chen L et al. status of seedlings is closely related to seedling culture trials and grown in a ventilated greenhouse quality (Elliott & White 1994, Close et al. 2005, at the Research Institute of Tropical Forestry, Birge et al. 2006) as it influences the survival rate Longdong. Quartz sand of 1–2 mm diameter of young seedlings, initial growth performance was washed with water and soaked in 1% HCl for and resistance to water stress, low temperature 24 hours to remove impurities, organic matter and disease (Van den Driessche 1991, Quoreshi & and nutrient residues. The sand was then Timmer 2000, Floistad & Kohmann 2004, Close et leached with running tap water, rinsed with al. 2005, Hawkins et al. 2005). Nutrient deficiency deionised water and finally wind dried. The experiments using tree seedlings are often used seedlings were transplanted into 18 × 13 × as a means of estimating the optimisation of 16 cm plastic pots filled with equal weights of nutritional management evaluating the effects of quartz sand and watered on alternate days. To nutrient deficiencies onseedling morphology and prevent runoff of water or leaching of nutrients, physiology (Timmer & Armstrong 1987, Barrett & white plastic bags were placed in the plastic Fox 1997, Trubat et al. 2006, Jeyanny et al. 2009). pots. The irrigation regime was measured by an Betula alnoides, also known as birch tree, is initial watering test in which water was poured a fast-growing indigenous hardwood species in slowly into a pot filled with quartz sand using northern India, Myanmar, Indochina and south a cylinder. When water was 2 cm from the China. It appears to be the most southerly species bottom of the pot, the volume of water added of Betula in the northern hemisphere. Some was the irrigation regime. This experiment was studies have shown that B. alnoides can grow well replicated four times. The real irrigation regime on all sorts of soils with pH ranging from 4.2 to was influenced by seedling growth demand and 6.5, probably because it is a strong deep-rooted weather condition. Fungi diseases were prevented species and able to form ectomycorrhiza or o by injecting a 2 /o o solution of carbendazin or vesicular-arbuscular mycorrhiza (Zeng et al. 1999, thiophanate into quartz sand every one or two Gong et al. 2000, Zeng et al. 2006). Therefore, this weeks. The average daytime temperature of the species often plays an important role in water greenhouse ranged from 24 to 29 °C, natural conservation, long-term maintenance of land light intensity from 110 to 140 µmol photon fertility and biodiversity of forest ecosystems. m-2 s-1 and relative humility from 48 to 71%. The Due to its well-formed stem, moderate density positions of the pots were rotated every two weeks and beautiful texture, the wood of B. alnoides to minimise edge effects. is commonly used for high-quality floorboards, The randomised complete block design was furniture and room decorations (Zeng et al. arranged with four blocks of seven treatments, 2006). Plantations of B. alnoides have been i.e.: complete nutrient mix (control), minus rapidly expanding in south China from 100 ha nitrogen (-N), minus phosphorus (-P), minus in the mid-1990s to more than 50 000 ha in 2005 potassium (-K), minus calcium (-Ca), minus (Zeng et al. 2006). Despite its rise as an important magnesium (-Mg) and minus sulphur (-S) economical and environmental species, little is nutrient solutions (n = 28). Each experiment known about the nutritional requirements of B. unit (plot) consisted of 10 seedlings, totalling alnoides, which may limit the optimal silviculture of this species. 280 seedlings in all treatments. The treatments The objective of this study was to identify the lasted for 12 weeks and started two weeks after visual symptoms of B. alnoides seedlings in response transplanting when all the seedlings were well to deficiencies of six major macronutrient established. Seedlings were supplied with 80 ml elements. The responses of B. alnoides seedlings of half-strength nutrient solutions (Table 1) once to nutrient deficiencies with regard to growth a week on the first six weeks and full-strength attributes, pigment composition and mineral thereafter. The test concluded when all the element contents were studied as these parameters treatments exhibited foliar symptoms. relate to improving the nutritional management The seedlings were observed daily for of B. alnoides plantations. symptoms of deficiency. The symptoms were recorded. The root collar diameter, height MATERIALS AND METHODS and number of branches of all seedlings were measured every three weeks. At the end of Healthy tissue-cultured seedlings of B. alnoides with the experiment, three of 10 seedlings per plot almost uniform height of 14.5 cm were used in sand were randomly selected and separated from the © Forest Research Institute Malaysia 404 Journal of Tropical Forest Science 22(4): 403–413 (2010) Chen L et al. Table 1 Chemical compositions (ml l-1) of complete and various macronutrient-lacking nutrient solutions Source Control -N -P -K -Ca -Mg -S -1 1 mol l KNO3 5 – 6 – 5 6 6 -1 1 mol l Ca(NO3)2 4H2O 5 – 4 5 – 4 4 -1 1 mol l MgSO4 2 2 2 2 2 – – -1 1 mol l KH2PO4 1 – – – 1 1 1 -1 0.5 mol l K2SO4 – 5 – – – 3 – -1 0.5 mol l CaCl2 – 10 – 10 – – – -1 1 mol l NaH2PO4 2H2O – 10 – 10 – – – -1 0.01 mol l CaSO4 2H2O – 20 – – – – – -1 1 mol l Mg(NO3)2 6H2O – – – – – – 2 0.05 mol l-1 Fe-EDTA 2 2 2 2 2 2 2 Arnon micronutrient solutions 1 1 1 1 1 1 1 -1 0.05 mol l H3BO3 -1 0.01 mol l MnCl2 4H2O -1 0.77 mmol l ZnCl2 -1 0.32 mmol l CuCl2 2H2O -1 0.09 mmol l H2MoO4(85%–90%MoO3) The pH of all nutrient solutions was adjusted to 6 with 1 mol l-1 NaOH or HCl.