Nutritional deficiency symptoms of young ‘cedro doce’ plants grown under macronutrient omission

ABSTRACT ‘Cedro doce’ [Pochota fendleri (Seem) Alverson & Duarte] is a native forest species in Amazon with great ecological and economic importance. Understanding nutritional requirements of the species allows cultivating Pochota fendleri with more efficient fertilization practices since its initial growth, as a seedling. Thus, this research aimed to evaluate the symptoms of nutritional deficiency of young ‘cedro doce’ plants. The experiment was carried out from September to December 2016, under greenhouse conditions, at Embrapa Roraima, in Boa Vista, RR, Brazil. The experiment was a randomized complete block design with seven treatments [complete solution and individual omission of the macronutrients (N, -P, -K, -Ca, -Mg, -S)] and three replications. Each experimental plot corresponded to a pot with one plant, corresponding to 21 plots. At 77 days after transplanting the seedlings to the pots, the plants were evaluated for symptoms of nutritional deficiency: total height, collar diameter, leaf number, chlorophyll a and b, chlorophyll a/b index ratio, shoot and root dry mass, and root/shoot ratio. The macronutrients omission caused nutritional deficiency symptoms in all ‘cedro doce’ plants. In general, P and N omission caused the least development of plants. This result is an indicative that ‘cedro doce’ is a high demanding species for both nutrients, especially phosphorus.

摘要：‘甜雪松’（Cedro doce）[学名：Pochota fendleri (Seem) Alverson & Duarte]是亚马逊原生森林树种，兼具极高的生态与经济价值。明晰该树种的营养需求，有助于在其幼苗生长初期采用更高效的施肥方案开展栽培。为此，本研究旨在评估甜雪松幼株的营养缺素症状。本试验于2016年9月至12月在巴西罗赖马州博阿维斯塔市的巴西农牧业研究公司罗赖马分公司（Embrapa Roraima）温室环境中开展。试验采用完全随机区组设计，设置7个处理组：全素营养液组以及大量元素（N、-P、-K、-Ca、-Mg、-S）单缺素组，共设3次重复。每个试验小区对应1盆种植1株幼苗的栽培单元，总计21个试验小区。将幼苗移栽至花盆77天后，对供试植株的营养缺素症状及相关指标进行测定，包括株高、茎粗、叶片数、叶绿素a与叶绿素b含量、叶绿素a/b比值、地上部与地下部干重及根冠比。所有缺素处理组的甜雪松植株均出现了营养缺素症状。总体而言，缺磷与缺氮处理对植株生长的抑制效果最为显著。该结果表明，甜雪松对氮、磷两种养分均有较高需求，其中对磷的需求尤为突出。