Felipe Manfio Somavilla, Alberto ​Cargnelutti Filho, Ismael Mario Márcio Neu, Daniela Lixinski Silveira, Valéria Escaio Bubans, Gabriel Elias Dumke

LEAF APPEARANCE RATE AND PHYLLOCHRON ON MILLET SOWING DATES

Introduction

Leaf appearance rate and phyllochron on millet sowing dates. Determine how millet sowing dates affect leaf appearance rate and phyllochron. Early sowing improves vegetative development, reducing leaf appearance period, thermal sum, and phyllochron.

Abstract

The objective of this study was to determine the leaf appearance rate and phyllochron as affected by millet sowing dates. The experiment was conducted with six sowing dates (11/28/2019, 12/03/2019, 12/10/2019, 12/17/2019, 12/30/2019 and 01/14/2020). The sowing was performed in plots with six rows of 2 m length and spacing of 0.25 m between rows. After emergence, for each sowing date, five plants were marked and the number of leaves was counted twice a week until flowering. For each plant relative to each sowing date (30 plants), the number of leaves (NL), leaf appearance period (LAP, in days), accumulated thermal sum (TSa, in ºC day), leaf appearance rate (LAR, on days leaf-1) and phyllochron in °C day leaf-1 were determined. Among the sowing dates, there is no variation in the number of leaves, with an average of 18.07 leaves. LAP varies between 49 and 88 days, TSa between 697.57 and 1299.47 °C day, LAR between 3.26 and 5.40 days leaf-1, and phyllochron between 45.05 and 80.81 °C day leaf-1. Millet shows better vegetative development (lower LAP, TSa, LAR and phyllochron) in early sowing (11/28/2019, 12/03/2019 and 12/10/2019) compared to later sowing (12/17/2019, 12/30/2019 and 01/14/2020).

Review

This study, titled 'Leaf Appearance Rate and Phyllochron on Millet Sowing Dates,' investigates the critical physiological parameters of leaf appearance rate (LAR) and phyllochron in millet, specifically examining how these are influenced by varying sowing dates. Understanding these metrics is vital for optimizing crop management and predicting plant development under different environmental conditions, thereby contributing to improved agricultural productivity. The research systematically explored the impact of six distinct sowing dates on these key developmental indicators. The experimental design involved establishing plots for six sowing dates spanning from late November 2019 to mid-January 2020. Post-emergence, five plants per sowing date were meticulously monitored, with leaf counts performed twice weekly until flowering. This rigorous data collection allowed for the determination of crucial parameters including the number of leaves (NL), leaf appearance period (LAP), accumulated thermal sum (TSa), leaf appearance rate (LAR), and phyllochron. While the total number of leaves remained consistent across all sowing dates, averaging 18.07, significant variations were observed in the other developmental metrics: LAP ranged from 49 to 88 days, TSa from 697.57 to 1299.47 °C day, LAR from 3.26 to 5.40 days leaf-1, and phyllochron from 45.05 to 80.81 °C day leaf-1. The most compelling finding of this study is the clear distinction in vegetative development based on sowing time. Millet exhibited superior vegetative development, characterized by lower values for LAP, TSa, LAR, and phyllochron, when sown earlier in the season (November 28, December 3, and December 10, 2019) compared to later sowing dates. This indicates that earlier planting leads to faster and more efficient leaf production, likely due to more favorable thermal conditions or resource availability during early growth stages. These results provide valuable insights for millet cultivation, strongly suggesting that optimizing sowing dates is a critical factor for maximizing the crop's vegetative vigor and overall productivity, offering practical guidance for farmers in similar growing environments.

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