Allometric relationship and leaf area modeling estimation on chia by non-destructive method

ABSTRACT This study aimed to obtain equations to estimate leaf area from linear leaf dimensions and establish the allometric relationship between leaf area and the number of leaves on the main stem of chia (Salvia hispanica L.) at different sowing times. The experiment was conducted in the agricultural year 2016/2017 on five sowing times in Santa Maria, RS, Brazil, in a randomized block design with four repetitions. In each plot, ten random plants were marked weekly during the vegetative phase to determine the number of leaves (NL) in the main stem, and three of these for the determination of leaf area (LA). A total of 70 leaves of different sizes were used to calibrate the model. Another 106 leaves were used to test the predictive capacity of the equations by various statistical indices. The length (L) and the largest leaf width (W) were measured. Leaf collection was carried out during the cycle, in all sowing times to represent all leaf sizes. The linear, quadratic, exponential, and potential models were adjusted. The non-destructive method, through the linear dimensions of the leaf, is appropriate for estimating the leaf area in chia. The general equation LA = 0.642 (L x W) can be used to estimate the leaf area of the chia plants without loss of precision. The potential model is appropriate to characterize the allometric relationship between leaf area evolution and the number of leaves accumulated in the main stem of chia at different sowing times.

摘要：本研究旨在基于叶片线性尺寸推导叶面积（Leaf Area, LA）估算方程，并明确不同播期下芡欧鼠尾草（Salvia hispanica L., chia）主茎叶面积与叶片数（Number of Leaves, NL）之间的异速生长关系（allometric relationship）。本试验于2016/2017农业年度在巴西南里奥格兰德州圣玛丽亚市开展，设置5个播期处理，采用随机区组设计（randomized block design）并设置4次重复。试验期间于营养生长期每周在每个小区随机标记10株植株，统计其主茎叶片数，并选取其中3株测定叶面积。共采集70枚不同大小的叶片用于模型校准，另选取106枚叶片通过多项统计指标验证方程的预测性能。测定指标包括叶片长度（Length, L）与最大叶宽（Width, W）。试验全程在所有播期内分期采集叶片，以覆盖全部叶尺寸区间。分别拟合线性、二次、指数及幂函数模型（potential model）。研究表明，基于叶片线性尺寸的非破坏性测定方法可有效估算芡欧鼠尾草的叶面积。通用估算方程LA = 0.642 × (L × W)可用于精准估算芡欧鼠尾草植株的叶面积，无精度损失。幂函数模型可有效表征不同播期下芡欧鼠尾草主茎叶面积动态与累积叶片数之间的异速生长关系。