GROWTH, PHYSIOLOGY AND YIELD OF FORMOSA 'PAPAYA' CULTIVATED UNDER DIFFERENT DOSES OF COATED AND CONVENTIONAL UREA

ABSTRACT Mineral fertilizer management is one of the most important agronomic techniques applied in papaya cultivation, which generally extracts large amounts of nutrients from soil, especially nitrogen. This study aimed to assess the phytotechnical and physiological attributes and yield of "Formosa‟ papaya hybrid Caliman 01 as a function of different doses of coated and conventional urea in the region of Bom Jesus - PI, Brazil. The treatments were arranged in a factorial scheme (2 × 4) and distributed in a randomized block design with four replications, corresponding to 2 nitrogen sources (coated urea, 43% of N; and conventional urea, 45% of N) and 4 doses nitrogen (350, 440, 530 and 620 g per plant). The N doses used corresponded to 80, 100, 120 and 140% of the nitrogen fertilization. It was used six plants per plot with two row borders, totaling 192 plants cultivated in the field. It was assessed the intercepted photosynthetically active radiation (int.PAR), radiation interception efficiency (PAREff.), leaf area index (LAI), plant height, stem diameter and yield. The coated urea promotes a higher growth and yield of "Formosa‟ papaya compared to the conventional urea. The application of 1.0 g of coated N promotes the production of 2.87 g of fruit per hectare while the application of 1.0 g of conventional N produces only 1.89 g of fruit per hectare, showing that the source of polymerized N increases the use efficiency of N applied to soil.

摘要
矿质肥料管理是番木瓜栽培中应用的核心农艺技术之一，其通常会从土壤中摄取大量养分，尤以氮素最为显著。本研究旨在评估巴西皮奥伊州邦热苏斯产区内，不同包膜尿素与常规尿素施用量对‘福尔摩沙’（Formosa）番木瓜杂交种Caliman 01的植物学与生理学特性及产量的影响。
试验采用2×4因子设计，以随机区组设计布置，设置4次重复；供试氮源分为2种：包膜尿素（氮含量43%）与常规尿素（氮含量45%），施氮剂量设4个梯度：每株350、440、530、620克。上述施氮剂量分别对应常规推荐施氮量的80%、100%、120%与140%。每个小区种植6株番木瓜，设置2行保护行，田间总栽培植株数为192株。本试验测定的指标包括光合有效辐射截获量（intercepted photosynthetically active radiation, int.PAR）、辐射截获效率（radiation interception efficiency, PAREff.）、叶面积指数（Leaf Area Index, LAI）、株高、茎粗与产量。
与常规尿素相比，包膜尿素可显著提升‘福尔摩沙’番木瓜的生长态势与产量水平。每公顷施用1.0克包膜态氮可生产2.87克果实，而每公顷施用1.0克常规态氮仅能生产1.89克果实，这表明聚合物包膜氮源可提升土壤施氮的利用效率。