การประเมินไนโตรเจนและคลอโรฟิลล์ในใบปาล์มน้ำมันโดยใช้คลอโรฟิลล์มิเตอร์

Abstract

Chlorophyll meter (SPAD-502) is a device which is used to assess rapidly chlorophyll and nitrogen content of leaves in the field with non-destructive leaves. The SPAD-502 meter measures the difference between the transmittance of a red and an infrared light through the leaf and as same as a prototype of chlorophyll meter (PSU-CM-1). The experiment was carried out to study the relationship between nitrogen and chrophyll content in oil palm leaves with SPAD-502-readings and PSU-CM-1-readings and to compare effectively for measurement of two device (SPAD-502 and PSU-CM-1). This experiment was conducted in oil palm variety SUP-PSU 1 with two stages of oil palm ages. The first one, sixteen-month seedlings stage was evaluated during December 2015 - February 2016. The second one, seven-year mature stage was evaluated during August - October 2016. The results showed that in seedlings stage. The relationship between total chlorophyll content (Chlota) with SPAD-502-readings and PSU-CM-1-readings were coefficient of determination (R') and described as a power regression: Chltotal = 0.0015SPAD 5256 (R? = 0.872") and Chltotal = 0.0047PSU: 2252 (R° = 0.834"). The relationship between chlorophyll a content (Chla) with SPAD-502-readings and PSU-CM-1-readings were coefficient of determination and described as a power regression: Chla = 0.0007SPAD 6363 (R? = 0.867) and Chla = 0.0026PSU1:3025 (R? = 0.839"). The relationship between chlorophyll b content (Chl,) with SPAD-502- readings and PSU-CM-1-readings were coefficient of determination and described as a power regression: Chl, = 0.001SPAD 3002 (R? = 0.845") and Chlo = 0.0024PSU 1.0564 (R? = 0.810*). Finally, the relationship between nitrogen content (N) with SPAD-502- readings and PSU-CM-1-readings were coefficient of determination and described as a linear regression: N = 1.4686SPAD - 31.685 (R? = 0.532") and N = 1.1609PSU - 18.254 (R° = 0.586"), respectively. However, mature stage, the relationship between total chlorophyll content (ChItotal with SPAD-502-readings and PSU-CM-1-readings were coefficient of determination and described as a polynomial regression: Chitotal = 0.0003SPAD* - 0.0276SPAD + 1.083 (R? = 0.610**) and Chltotal = 4E-05PSU₴ + 0.0126PSU - 0.0924 (R? = 0.574*). The relationship between chlorophyll a content (Chla) with SPAD-502-readings and PSU-CM-1-readings were coefficient of determination and described as a polynomial regression: Chla = 0.0002SPAD* - 0.0167SPAD + 0.6887 (R? = 0.691") and Chla = 1E-04PSU 2 + 0.0001PSU + 0.2425 (R? = 0.652*). The relationship between chlorophyll b content (Chl) with SPAD-502-readings and PSU-CM-1-readings were coefficient of determination and described as a polynomial regression: Chl = 9E-05SPAD? - 0.0065SPAD + 0.2501 (R? = 0.552"*) and Chlo = 4E-05PSU2 - 0.0003PSU + 0.0686 (R? = 0.550*). Finally, the relationship between nitrogen content (N) with SPAD-502-readings and PSU-CM-1-readings were coefficient of determination and described as a linear regression: N = 0.3584SPAD - 1.0646 (R2 = 0.609**) and N = 0.2314PSU + 9.1976 (R? = 0.467*), respectively. The precise comparison of measurement between SPAD-502 and PSU-CM 1 in seedlings and mature stages, it was found that linear regression was expressed as: SPAD = 0.801PSU + 8.7567 (R? = 0.921") and SPAD = 0.7886PSU + 19.918 (R? = 0.771*), respectively. Consequently, the portable chlorophyll meter SPAD-502 could be used to assess nitrogen and chlorophyll content of seedlings and mature stage with non-destructive oil palm leaves. The prototype of chlorophyll meter (PSU-CM-1) was only predicted to assess total nitrogen and chlorophyll contents of seedlings. However, the prototype showed that it was lower accurate in mature stage when it was compared with the SPAD-502 meter. Therefore, the prototype needs to be improved further.