Journal of Plant Pathology & Microbiology

Spectral reflectance and physiological studies of Cocoa leaves in response to Macronutrients deficiency

3^rd International Conference on Plant Science & Physiology

May 21-22, 2018 Osaka, Japan

Tee Yei Kheng, Siva Kumar Balasundram, Phebe Ding and Ahmad Husni Mohd Haniff

University Putra Malaysia, Malaysia

Posters & Accepted Abstracts: J Plant Pathol Microbiol

Abstract:

In cocoa (Theobroma cacao), macronutrients of nitrogen (N), phosphorus (P) and potassium (K) are the essential elements that may drastically affect growth, appearance and most importantly, yield. However, detection of macronutrients can be slow while nutrient analysis can be time consuming. Adaptation of hyperspectral analysis techniques along with physiological study for the determination of specific nutrient stress in cocoa could allow early detection and precision in fertilization. The objective of the study was to investigate the prediction possibility of N and K deficiency in cocoa seedlings using a spectroradiometer. Spectral reflectance of fully expanded cocoa leaves from 350 to 1000 nm; growth (height, girth, leaf area) and physiological studies (photosynthesis, transpiration rate, chlorophyll content) were measured at monthly intervals for 3 months after treatment. A total of 72 seedlings (3 treatments x 4 replication x 6 sampling = 72 seedlings) with treatments (T1: 15-N: 15-P: 15-K; T2: 0-N: 15-P: 15-K; T3: 15-N: 15-P: 0-K) were arranged in a factorial randomized complete block design replicated four times in a greenhouse. Multispectral reflectance showed that leaves with no N (T2) had the highest reflectance peak at about 550 nm as absorption of incident light by chlorophyll decreased. This was further supported by T2 cocoa seedlings with significantly lowest readings in growth, net photosynthesis, transpiration rate and chlorophyll content (Pâ?¤0.05). Next, cocoa seedlings with no N and K involved response to nutrient stress by showing a shift in the red edge with greater reflectance at 675-750 nm. This is because healthy cocoa seedlings with complete ratio of NPK absorbed light as energy for photosynthesis and reflect near infrared light by bouncing off from the mesophyll layer. Overall, reflectance measurements could be a powerful non-destructive technique to decide on fertilizer application and timely correction of nutrient deficiencies before irreversible stress or damage occurs.

Biography :

Ms. Tee Yei Kheng is a research officer in Malaysian Cocoa Board since 2013 and currently, she is also a PhD candidate in Universiti Putra Malaysia (UPM). She has the research interests in plant physiology and precision agriculture. Ms. Tee is also the Head of Project for a research funding under 11th Malaysian Plan (20162020) with 10 research projects have been carried out to study the effects of climate changes on cocoa productivity. Despite that, she has the interests in applying Geographical Information System (GIS) and spectral reflectance of cocoa in response to nutrient deficiency and plant stress through precision cocoa management which grant her another research funding under 11th Malaysian Plan for 5 years (2016-2020). She was the first Borlaug Fellow from Malaysia in 2015 to join The Norman E. Borlaug International Agricultural Science and Technology Fellowship Program. This program was supported by World Cocoa Foundation and the U.S. Department of Agriculture Foreign Agricultural Service.
Email:teeyeikheng@gmail.com