Monitoring cotton (Gossypium hirsutum L.) leaf ion content and leaf water content in saline soil with hyperspectral reflectance

Abstract

The objectives of this study were to establish quantitative models for monitoring the leaf ion and water content under saline conditions. The best spectral indices for estimating leaf ion content and leaf water content were found to be normalized difference spectral indices (NDSI (R 1340 , R 2306 )), ratio spectral indices (RSI (R 2306 , R 1347 )) for K 2-and NDSI (R 1222 , R 2264 ), RSI (R 2264 , R 1321 ) for RWC, respectively. The regression models based on the above spectral indices were formulated with R 2 greater than 0.46. The high fit between the measured and estimated values indicate that the present models based on RSI could be used to estimate leaf ion and water content feasibly under saline conditions.

Ability of Modified Spectral Reflectance Indices for Estimating Growth and Photosynthetic Efficiency of Wheat under Saline Field Conditions

“…Various changes in biophysical and biochemical characteristics of the canopy (such as leaf chlorophyll and other photosynthetic pigments contents, leaf tissue structure, dry matter accumulation, photosynthetic efficiency, and plant water status) have been found to be change in relation to osmotic and ionic components of salinity stress, and these cause noticeable variability in the spectral reflectance of the canopy in the three parts of the spectrum (VIS, NIR, and SWIR) domains [4,21,25,26]. Therefore, several SRIs that incorporate wavelengths related to the abovementioned main physiological characteristics of plants were modified to indirectly estimate the growth and photosynthetic efficiency of crops under various environmental conditions.…”

“…For example, Poss et al [23] found that the water band index (WBI = (R 900 /R 970 )), which incorporates one of the water absorption bands from the NIR region (970 nm), reflects the response of wheatgrass growth (Agropyron elongatum L.) to salt stress. In addition, El-Hendawy et al [25] reported that SRIs combining the NIR and SWIR wavebands are suitable for assessing the growth of spring wheat under salt stress, and SRIs incorporating the NIR band (1321 nm) and SWIR band (2264 nm) was found to be important for assessing responses of the growth of cotton plant to salt stress [26].…”

On the use of spectral reflectance indices to assess agro‐morphological traits of wheat plants grown under simulated saline field conditions

“…At the milk grain stage, in general, the SRIs covered canopy chlorophyll content such as the PARS-a, PARS-b, and MCARI were found to be efficient for assessing agro-morphological traits, especially for the salt-sensitive genotype (Pearson correlation coefficients ranging from 0.77 to 0.95) ( (Jaleel, Sankar, Sridharan, & Panneerselvam, 2008;Munns et al, 2006;Zhang, Ma et al, 2014;Zhang, Zhou, Zhang, Meng, & Wang, 2014).…”

“…As shown in Figure 2, it was noticed that the most effective SRIs for assessing grain yield under salinity conditions were those that combined visible (VIS, 350-750 nm) and near-infrared (NIR, 750-1350 nm) wavelengths such as NDVI, EVI-2, SIPI, and RMSI or combined NIR and shortwave-infrared (SWIR, 1350-2500 nm) wavelengths such as ratio spectral index (RSI, 2264(RSI, :1321. From previous investigations, it can be concluded that such SRIs are related to bands of the pigment contents, internal leaf structure, and water status of canopy and most of these wavebands are very sensitive to salinity stress (Hamzeh et al, 2012;Krezhova, Kirova, Yanev, & Iliev, 2009;Rud et al, 2011;Sims & Gamon, 2002;Zhang, Zhou et al, 2014). For instance, Krezhova et al (2009) reported that the bands related to pigments such as the green band (520-580 nm), red band (640-680 nm), and NIR band (720-770 nm) were strongly affected by salinity stress in soybean plants.…”

“…For instance, Krezhova et al (2009) reported that the bands related to pigments such as the green band (520-580 nm), red band (640-680 nm), and NIR band (720-770 nm) were strongly affected by salinity stress in soybean plants. The NIR band (1321 nm) and SWIR band (2264 nm) that incorporated in the RSI have been shown to be related to the internal leaf structure and canopy water status of cotton under saline conditions (Hamzeh et al, 2012;Zhang, Zhou et al 2014). The spectral regions in both the red edge and NIR such as the wavebands at 731-762, 812-868, 884-809, and 918-930 nm were proposed to be the most sensitive bands in salt-tolerant plants (Zhang et al, 2011).…”