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Leaf Chlorophyll Dynamics in Wheat Based on Spad Meter Reading and Its Relationship with Grain Yield

M Rafiqul Islam
Department of Agronomy, Bangabandhu Sheikh Mujibur Rahman Agricultural University Gazipur-1706, Bangladesh

K M Shamsul Haque
Department of Agronomy, Bangabandhu Sheikh Mujibur Rahman Agricultural University Gazipur-1706, Bangladesh

Nurunnaher Akter
Department of Agronomy, Bangabandhu Sheikh Mujibur Rahman Agricultural University Gazipur-1706, Bangladesh

M Abdul Karim
Department of Agronomy, Bangabandhu Sheikh Mujibur Rahman Agricultural University Gazipur-1706, Bangladesh

Abstract/ Executive Summary:

The SPAD chlorophyll meter is useful for rapid analysis of chlorophyll and nitrogen status of crops, while it has not been established how strongly the meter readings are correlated with grain yield under variable field conditions. The objective of the study was to establish a relationship between leaf SPAD readings and grain yield of wheat grown under different fertilizer management options. The plants receiving full amount of inorganic fertilizers showed consistently higher SPAD reading compared to those received reduced inorganic fertilizers and/or organic fertilizers and, thus giving the higher grain yield. The SPAD values were positively correlated with grain yield at different growth stages. The highest correlation (r=0.99*) corresponded to 70 days after sowing (DAS). The SPAD values of flag leaves were significantly affected by differential fertilizer management and having positive strong correlations with grain yield at different growth stages of wheat. The higher correlation coefficient value indicated that the SPAD values of flag leaves up to 96 DAS are important for predicting grain yield in wheat. From the multiple regression model, this implies that the maintenance of optimal leaf chlorophyll contents between 50-75 DAS is imperative for obtaining higher grain yield. The study also demonstrated the importance of using SPAD mater in determining wheat yield under variable fertilizer management under field conditions.

Keywords: Leaf chlorophyll, Nitrogen, SPAD value, Wheat, Grain yield

Location: Experimental field of Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur

Start Date: 00-00-2009

End Date:

Program Area: Crop-Soil-Water Management

Commodity: Wheat

Objectives:

To establish a relationship between leaf SPAD readings and grain yield of wheat grown under different fertilizer management options.

Methodology:

A field experiment was conducted during rabi 2009 growing season at the experimental field of Bangabandhu Sheikh Mujibur Rahman Agricultural University (24^o02'19''N latitude and 90^o23'48''E longitude; 8 m elevation). The average temperature ranges from 21-35^oC during the experimentation. The soil was clay loam in texture and slightly acidic in reaction with very low contents of nitrogen and phosphorus. Fertilizer management treatments were T₁ - full dose inorganic fertilizer @ 220 kg urea (N), 142 kg triple super phosphate (P), 136 kg muriate of potash (K), 128 kg gypsum (S) and 2.6 kg ZnSO₄ (Zn) per hectare; T₂ - half dose inorganic fertilizers + half dose cowdung; T₃ - half dose inorganic fertilizers + half dose compost; T₄ - half dose inorganic fertilizers + half dose poultry liter; T₅ - full dose cowdung; T₆ - full dose compost and T₇ - full dose poultry liter. One third N fertilizer, and other inorganic and organic fertilizers were applied as basal dose and the rest N fertilizer was applied by two equal splits at 25 and 50 DAS. The experimental treatments were arranged in randomized complete block design with three replications. Each experimental plot was 4 m long and 3 m wide consisting of three rows with one m inter-row spacing. The seeds of wheat variety Sonalika were sown at row to row spacing of 30 cm. The plots were kept weed-free and maintained in an optimum soil moisture regime throughout the experimental period. A chlorophyll meter (SPAD-502, Minolta, Japan) was used to obtain readings estimating leaf chlorophyll concentration (SPAD value). Ten plants per treatment were selected randomly and SPAD values were recorded from the fully matured leaves counted from the top of the plants, the youngest fully expanded leaf. As such data were recorded at 5 days intervals during 45-75 DAS. Three SPAD readings were taken per plant and thus each SPAD value represents a mean of 90 readings per treatments. Similarly, SPAD values of flag leaves were recorded starting from 67 DAS until 102 DAS at 3/4 days interval. The plants were harvested by hand at ground level at maturity from ten selected plants for yield estimation. Grains were separated from straw and then dried in the sun. The weight of grain and straw was recorded and corrected to 12% moisture content. All data were analyzed statistically following the standard procedures as described. The correlations between fertilizer application levels and grain yield, SPAD value and grain yield were tested at 5% level of significance. A relationship between chlorophyll meter readings and grain yield of wheat were developed using regression equation. Correlation and regression analysis were done using standard statistical methods (SPSS 12).

Source of Information: Sci. Agri. 8 (1), : 13-18, 2014

Article Link (Online Journal):

Funding Source:

1. Government

Budget:

Total Budget (Tk.) :

Achievement/Findings:

From the multiple regression model, it is clear that there are strong significant effects of SPAD values at 50 DAS and continued to 75 DAS corresponding to the vegetative and reproductive stages of crop. This implies that maintaining of leaf chlorophyll content during this period is very important for higher grain yield. The correlation between annual average predicted and observed yield was r= 87*. This indicated that fertilizer induced variation in yields was more easily accounted for by SPAD reading differences according to the regression model.

Knowledge Management: Journal