Greenness‐Leaf Area Index Relationships of Seven Row Crops¹

Abstract

Remote sensing technology has potential for nondestructive estimation of green leaf area index (LAI). We applied the greenness transformation to ground-based reflectance data taken over seven crops (sweet and field corn, Zea mays L.; grain sorghum, Sorghum bicolor (L.) Moench; pearl millet, Pennisetum americanum (L.) Leeke; pinto bean, Phaseolus vulgaris L.; soybean, Glycine max (L.) Merr.; and sunflower, Helianthus annuus L.] grown on Eudora silt loam soil (coarse-silty, mixed, mesic Fluventic Haplodoll) to determine reflectance-LA! relationships, and to see if those relationships were crop specific or could be applied more generally to several crops. Spectral reflectance data were collected with a radiometer equipped with four wavelength bands that simulated the Landsat multispectral scanner bands. The coefficients for brightness and greenness were calculated by using reflectance data and published calculation procedures. Greenness coefficients for the reflectance data for all crops were very similar. Models were developed that related greenness (calculated by using the individual crop greenness coefficients or the coefficients developed from combined data of all crops) and field estimates of green LAI. All models were significant (P<O.OOOI) and linear, with the regression coefficients equal to what we termed the crop factor. Intercepts were not significantly different from zero (P>O.OS). The combined greenness coefficients were not significantly different than individual crop coefficients in relating greenness to field-estimated LAI. The crops were grouped into grass or broadleaf to determine general crop factors. It made no significant difference whether the individual crop factor or the combined crop factor (for grass, 0.197; for broadleaf, 0.117) was used in developing the greenness-estimated LAI that was related to field-estimated LAI. This study illustrated that the greenness coefficients developed for each of seven row crops were very similar and the regression coefficients from the linear relationship between LAI and reflectance greenness were very similar within the grass crops and within the broadleaf crops.

Application of Spectral Remote Sensing for Agronomic Decisions

“…The most widely used VI is the Normalized Difference Vegetative Index (NDVI) proposed by Deering (1978) that now serves as somewhat of a benchmark for researchers developing new VIs. The NDVI has been shown to be strongly related to light interception (Hatfield et al, 1984a; Redelfs et al, 1987; Richardson et al, 1992; Sellers, 1987; Serrano et al, 2000; Verma et al, 1992; Wiegand and Hatfield, 1988; Wiegand et al, 1990, 1992; Russel et al, 1995). Interference from underlying soil reflectance, especially for incomplete canopy cover, has been a weakness for many VIs.…”

Estimation of Nitrogen Uptake and Yield of Tobacco (Nicotiana tobacum L.) by Reflectance Indices of Ground-based Remote Sensors

“…성을 분석하여 그에 따른 변량시비가 가능한 장점이 있다 (Redelfs et al, 1987;Wiegand et al, 1990Wiegand et al, , 1991Wiegand et al, , 1992Daughtry et al, 1992;Yoder et al, 1995;Cater et al, 2001Cater et al, , 2002Lihong et al, 2004 (Pinter et al, 1985;Tarpley et al, 2000;Rundquist et al, 2004 평가하였다 (Varvel et al, 1997;Hussain et al, 2000). …”

Estimation de faibles indices foliaires d'une culture de luzerne par mesure de réflectances hémisphériques dans le rouge clair (660 nm) et le rouge sombre (730 nm)

“…C'est en particulier le cas du modèle de production potentielle de luzerne proposé par Gosse et al (1984) et Lemaire et Allirand (1993). Le L'une des solutions adoptées consiste à utiliser des relations statistiques reliant l'indice foliaire à l'évolution de la température de l'air, quantifiée en termes de somme de degrés-jour (Onstad et Fick, 1983 ;Gosse et al, 1984,...) ; la forte variabilité génétique de la vitesse de repousse après défolia-tion (Canal, 1993) (1959, 1963a, b), se sont dévelop-pées des méthodes indirectes fondées sur la mesure de la probabilité directionnelle d'interception du rayonnement (Bonhomme et Chartier, 1972 ;Lang, 1987...) (Varlet-Grancher, 1974 (Asrar et al, 1985 ;Best et Harlan, 1985 ;Hatfield et al, 1985 ;Baret, 1986 ;Redelfs et al, 1987...), ou à l'efficience de l'absorption du rayonnement visible (Kimes et al, 1981 ;Daughtry et al, 1983 ;Asrar et al, 1984 ;Hatfield et al, 1984 ;Baret et al, 1988...) ont déjà été étudiées à partir de modèles de transferts radiatifs (Sellers, 1985). Les combinaisons les plus simples sont des rapports ou des différences de réflectance, éventuellement normées (Rouse et al, 1974) ; mais il existe aussi des indices de végéta-tion plus complexes, quoique souvent fonctionnellement équivalents (Perry et Lautenschlager, 1984).…”