Leaf area of seedlings of urucum (Bixa orellana L.) estimated by different methods: A comparative analysis

Abstract

Leaf area (LA) determination of the crops is a parameter indicative of growth and yield, and precise and accurate methods for its estimation are very important. Urucum (Bixa orellana L.) is an arboreal species, native to the Amazon Rainforest and Atlantic Forest, with economic importance due to its natural dye seed extracts. Thus, the aim of this paper is to compare different methods for LA determination in Urucum seedlings. To do so, the planimetric method was considered the standard method and its equivalence to the method based in leaf size parameters — length (L) and width (W) — and the scanner method were tested. In the method based in leaf size parameters, the f of 0.64 was previously adjusted for the annatto by regression analysis between LA and the C xL product. In the scanner method, the ImageJ app was used to determine the LA. Linear regression without intercept between LA through the standard method and LA estimated through each alternative method was used to check the conformity between the results. Leaf size and scanner methods were equivalent to the standard method (5% error probability) and equivalent to each other (1% error probability). Thus, these methods can be reliably used for estimating the Urucum leaf area. However, the dimension method has practical advantages compared to the others as it is a nondestructive method.