The main task of this research was to evaluate canopy temperature and Crop Water Stress Index (CWSI) by assessing genotype variability of maize performance for different water regimes. To that end, three hundred tropical and subtropical maize hybrids with different phenology in terms of date of anthesis were evaluated. The influence of phenology on the change in canopy temperatures and CWSI was not equal during the three dates of measurement. At the end of vegetative growth (82 days after sowing, DAS) and at the blister stage (DAS 97), a high significant difference in temperatures and CWSI (P < 0.001) were obtained between the early‐ and late‐maturity genotypes. During anthesis (DAS 89), phenology had a significant effect (P < 0.01) only for the well‐watered genotypes, while under water‐stress conditions, no differences were found between early and late genotypes in terms of canopy temperature and CWSI. High significant differences (P < 0.001) in stomatal conductance (gs) between early and late genotypes for different treatments were observed. A relationship (R2 = 0.62) between gs and canopy temperature was obtained. Under a water‐stress canopy, temperature was measured at anthesis, which was negatively correlated with grain yield of the early (r = −0.55)‐ and late (r = −0.46)‐maturity genotypes in the water‐stressed condition.
Abstract:The Tarim River Basin, the largest area of Chinese cotton production, is receiving increased attention because of serious environmental problems. At two experimental stations (Korla and Aksu), we studied the influence of salinity on cotton yield. Soil chemical and physical properties, soil water content, soil total suction and matric suction, cotton yield and water use efficiency under plastic mulched drip irrigation in different saline soils was measured during cotton growth season. The salinity (mS·cm −1 ) were 17-25 (low) at Aksu and Korla, 29-50 (middle) at Aksu and 52-62 (high) at Aksu for ECe (Electrical conductivity measured in saturation-paste extract of soil) over the 100 cm soil profile. The soil water characteristic curves in different saline soils showed that the soil water content (15%-23%) at top 40 cm soil, lower total suction power (below 3500 kPa) and lower matric suction (below 30 kPa) in low saline soil at Korla had the highest water use efficiency (10 kg·ha
Biotic factors such as pests and pathogens cause a substantial damage to wheat crops which leads to reduction in yield in a range from 10% to 50%. Application of fungicides and pesticides on one hand protects the crop but it also increases the crop production cost. Pathogens affect photosynthesis, respiration, translocation of water and nutrients of the crop and mostly the visual symptoms are detected too late to protect the crop. The objective of this study was to detect the plant fungal diseases by non-invasive sensor technologies and to determine the early outbreak of the disease. The experiment was conducted in the greenhouse where the two wheat cultivars namely; Monopol and Kalahari were infected with three fungal diseases viz. Fusarium culmorum, Septoria tritici and Blumeria graminis f.sp. tritic. Throughout the experiment four spectral sensors were used namely, Isaria, Handyspec, Multiplex and Infrared thermal camera. The results showed that as early as 2 days after inoculation (DAI), an increase in the average canopy temperature and maximum temperature difference within the canopy (MTD) was observed. Similarly, the REIP calculated from Handyspec showed significant difference between the infested and the control plants before the visual symptoms appeared. Multiplex measured chlorophyll content which is related to the photosynthesis process allowed to detect the early symptoms in contrast to the Isaria which, does not show a significant difference between control and infected plants.
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