16.精子形成のホルモン支配(第669回千葉医学会例会・第38回千葉泌尿器科集談会)

Understanding the temporal and spatial variability in a crop yield is viewed as one of the key steps in the implementation of precision agriculture practices. Therefore, a study on a center pivot irrigated 23.5 ha field in Saudi Arabia was conducted to assess the variability in alfalfa yield using Landsat-8 imagery and a hay yield monitor data. In addition, the study was designed to also explore the potential of predicting the alfalfa yield using vegetation indices. A calibrated yield monitor mounted on a large rectangular hay baler was used to measure the actual alfalfa yield for four alfalfa harvests performed in the period from October 2013 to May 2014. A total of 18 Landsat-8 images, representing different crop growth stages, were used to derive different vegetation indices (VIs). Data from the yield monitor was used to generate yield maps, which illustrated a definite spatial variation in alfalfa yield across the experimental field for the four studied harvests as indicated by the high spatial correlation values (0.75 to 0.97) and the low P-values (4.7E-103 to 8.9E-27). The yield monitor-measured alfalfa actual yield was compared to the predicted yield form the Vis. Results of the study showed that there was a correlation between actual and predicted yield. The highest correlations were observed between actual yield and the predicted using NIR reflectance, SAVI and NDVI with maximum correlation coefficients of 0.69, 0.68 and 0.63, respectively

Employment of GIS techniques to assess the long-term impact of tillage on the soil organic carbon of agricultural fields under hyper-arid conditions.

A study on six 50 ha agricultural fields was conducted to investigate the effect of conservation tillage practices on the long-term (1990-2016) changes in the soil organic carbon (SOC) content of the topsoil layers (0-10 cm) of agricultural fields. The experimental fields were selected from the 49 fields of the Tawdeehiya Arable Farm (TAF), located 200 kilometers southeast of Riyadh, the capital city of the Kingdom of Saudi Arabia. Data sets from laboratory determined SOC and the corresponding Landsat images generated vegetation indices, namely, the Normalized Difference Vegetation Index (NDVI) and the Bare Soil Index (BSI), were utilized for the prediction of SOC using multivariate regression techniques. Long-term changes in the SOC content of the experimental fields, as a result of different tillage practices, were also studied. The developed SOC prediction models exhibited high accuracy indicated by R2 values ranging from 0.73 to 0.85, RMSE values of 0.34 to 0.85 g kg-1 and P-values of less than 0.0001. The cross-validation results (R2 of 0.61-0.70, RMSE value of 0.34-0.85 g kg-1 and P-values of less than 0.0001) confirmed the high accuracy of the developed SOC prediction models. Results also revealed that the change in the SOC content was clearly associated with soil tillage practices. On the average, 76% of the all agricultural fields in the experimental farm showed a decrease of up to 24 g kg-1 in their SOC content after 10 years (1990-2000) of continuous conventional tillage practices. On the other hand, an average increase of up to 37 g kg-1 in the SOC content was observed in 88% of the studied fields at the end of the study period (2016), where conservation tillage was a continous and consistent practice in the experimental farm

Seed Priming with Nanoparticles and 24-Epibrassinolide Improved Seed Germination and Enzymatic Performance of Zea mays L. in Salt-Stressed Soil

Saline stress is one of the most critical abiotic stress factors that can lessen crops’ productivity. However, emerging nanotechnology, nano-fertilizers, and developing knowledge of phytochromes can potentially mitigate the negative effects of saline stress on seed germination. Therefore, the aim of this study was to investigate the effects of seed priming either with zinc oxide nanoparticles (ZnO-NPs; 50 and 100 mg L−1) or 24-epibrassinolide (EBL; 0.2 and 0.4 μM) and their combinations on maize (Zea mays L.) grains sown in salt-stressed soil (50 and 100 mM NaCl). Saline stress treatments significantly affected all germination traits and chemical analysis of seeds as well as α-amylase activity. Compared to un-primed seeds, seed priming with ZnO-NPs or EBL and their combinations significantly increased the cumulative germination percentage, germination energy, imbibition rate, increase in grain weight, K+ content, and α-amylase activity, and significantly reduced germination time, days to 50% emergence, Na+ uptake, and Na+/K+ ratio of maize sown in salt-stressed-soil (50 or 100 mM NaCl). The combination of 100 mg ZnO-NPs L−1 + 0.2 μM EBL resulted in the highest improvements for most of the studied traits of maize seeds sown in salt-stressed soil in comparison to all other individual and combined treatments

Seed Priming with Nanoparticles and 24-Epibrassinolide Improved Seed Germination and Enzymatic Performance of <i>Zea mays</i> L. in Salt-Stressed Soil

Saline stress is one of the most critical abiotic stress factors that can lessen crops’ productivity. However, emerging nanotechnology, nano-fertilizers, and developing knowledge of phytochromes can potentially mitigate the negative effects of saline stress on seed germination. Therefore, the aim of this study was to investigate the effects of seed priming either with zinc oxide nanoparticles (ZnO-NPs; 50 and 100 mg L−1) or 24-epibrassinolide (EBL; 0.2 and 0.4 μM) and their combinations on maize (Zea mays L.) grains sown in salt-stressed soil (50 and 100 mM NaCl). Saline stress treatments significantly affected all germination traits and chemical analysis of seeds as well as α-amylase activity. Compared to un-primed seeds, seed priming with ZnO-NPs or EBL and their combinations significantly increased the cumulative germination percentage, germination energy, imbibition rate, increase in grain weight, K+ content, and α-amylase activity, and significantly reduced germination time, days to 50% emergence, Na+ uptake, and Na+/K+ ratio of maize sown in salt-stressed-soil (50 or 100 mM NaCl). The combination of 100 mg ZnO-NPs L−1 + 0.2 μM EBL resulted in the highest improvements for most of the studied traits of maize seeds sown in salt-stressed soil in comparison to all other individual and combined treatments

Satellite-Based Determination of the Water Footprint of Carrots and Onions Grown in the Arid Climate of Saudi Arabia

Increasing demand for food, climate change, and other human interventions are leading to significant increases in water consumption by the agricultural sector. This requires rationalizing the water used for the production of agricultural crops through improved irrigation management practices. Therefore, this study aimed to estimate the water footprint (WF) of onion (Allium cepa L.) and carrot (Daucus carota) crops using the CROPWAT model and the SSEB (Simplified Surface Energy Balance) algorithm. Experiments were carried out at two center-pivot irrigated fields belonging to Tawdeehiya Commercial Farms in the southeastern region of the Riyadh governorate, Saudi Arabia. Individual bands and vegetation indices (VIs) were retrieved from Sentinel-2 satellite data, including the normalized difference vegetation index (NDVI), soil adjusted vegetation index (SAVI), optimized soil adjusted vegetation index (OSAVI), renormalized difference vegetation index (RDVI), and enhanced vegetation index (EVI), and the land surface temperatures (LST) extracted from Landsat-8 data were used to estimate crop productivity (CP), crop water use (CWU) (i.e., evapotranspiration—ETa), and crop WF. Crop growth/phenology stages and georeferenced biophysical parameters were recorded during the growth period, and crop yield samples were collected randomly from predetermined sampling locations. It was found that the NIR band was appropriate for predicting onion yield (R2 = 0.68; p > F = 0.02) and carrot yield (R2 = 0.77; p > F = 0.02). The results also showed the feasibility of using the RDVI and EVI to estimate the yields of onion and carrot crops, with bias values of 15% and –17%, respectively. The CWU has also been successfully estimated using the SSEB algorithm, with an overall accuracy of 89%. The SSEB-estimated CWU was relatively high compared to the applied amounts by 10.6% (onions) and 12.6% (carrots). Finally, the crop WF was successfully estimated at 312 m3 t−1 and 230 m3 t−1 for carrots and onions, respectively, with an overall accuracy of 71.11%. The outcomes of this study can serve as a reference for crop irrigation management practices in the study region and areas with similar environmental conditions

Impact of water salinity levels on the spectral behavior and yield of tomatoes in hydroponics

In Saudi Arabia, irrigation water is mainly obtained from aquifers and is mostly characterized by moderate to high levels of salinity. Hence, detailed information on crop response to salinity is of great importance in order to optimize irrigation and fertilizer management. Therefore, this study was conducted to evaluate the effect of salinity and grafting on the spectral behavior and yield of three tomato (Solanum lycopersicum) cultivars (Valouro-RZ, Ghandowra-F1 and Feisty-Red) grown in a hydroponic glass greenhouse. Three salinity levels (2.5, 6.0 and 9.5 dS m−1) were used in this study. For the three tomato cultivars, the increase in salinity level was associated with an increase in the spectral reflectance in the Visible, Red-Edge and NIR regions of the electromagnetic spectrum. However, Valouro-RZ and Feisty-Red cultivars showed no significant differences in the spectral reflectance in the Visible range between salinity1 (2.5 dS m−1) and salinity2 (6.0 dS m−1). Slight reduction, but not significant, in the total fruit yield was recorded under salinity2 compared to salinity1 (2.5 dS m−1) for Valouro-RZ (6.76%) and Feisty-Red (6.79%). For salinity3 (9.5 dS m−1), significant reductions in total fruit yield were recorded compared to salinity1 (Valouro-RZ: 31.77%, Feisty-Red: 33.53%). Ghandowra-F1 cultivar was found to be the most salt tolerant among the studied tomato cultivars, where a significant reduction was observed in the total fruit yield only when the salinity increased from 2.5 to 6.0 dS m−1 (10.85%) and 9.5 dS m−1 (30.63%). Grafting on Maxifort rootstock showed neither a significant effect on the spectral response nor a significant yield improvement; hence, no positive change in salinity tolerance, due to grafting, of the studied tomato cultivars. Therefore, further research on rootstock and fruit variant combinations for the feasibility of grafting for salinity tolerance is necessary. The results of this study indicated that the Valouro-RZ and Feisty-Red tomato cultivars could be grown successfully under a hydroponic system using irrigation water of up to 6.0 dS m−1 salt concentration without sacrificing the total fruit yield while taste may improve

Integrating Tillage and Mulching Practices as an Avenue to Promote Soil Water Storage, Growth, Production, and Water Productivity of Wheat under Deficit Irrigation in Arid Countries

Ensuring food security with limited water resources in arid countries requires urgent development of innovative water-saving strategies. This study aimed to investigate the effects of various tillage and mulching practices on soil water storage (SWS), growth, production, irrigation water use efficiency (IWUE), and water productivity (WP) of wheat under full (FL) and limited (LM) irrigation regimes in a typical arid country. The tillage practices comprised the conventional tillage (CT) and reduced tillage (RT), each with five mulching treatments (MT), including non-mulched (NM), plastic film mulch (PFM), wheat straw mulch (WSM), palm residues mulch (PRM), and a mixture of wheat straw and palm residues at 50/50 ratio (MM). Results showed higher SWS at different measured time points in CT than RT at 20–40 cm, 40–60 cm, and 0–60 cm soil depth under FL regime, and at 40–60 cm under LM regime, while the opposite was observed at 0–20 cm and 20–40 cm soil depth under LM regime. SWS at different soil depths under MT, in most cases, followed the order of PFM > PRM ≈ MM > WSM > NM under FL, and PFM ≈ PRM > MM > WSM > NM under LM regimes. No significant differences were observed for traits related to growth between CT and RT, but RT increased the traits related to yield, IWUE, and WP by 5.9–11.6% than did CT. PFM and PRM or PRM and MM showed the highest values for traits related to growth or yield, IWUE, and WP, respectively. No significant differences in all traits between CT and RT under the FL regime were observed, however, RT increased all traits by 8.0–18.8% than did CT under the LM regime. The yield response factor (Ky) based on plant dry weight (KyPDW) and grain yield (KyGY) under RT was acceptable for four MT, while KyGY under CT was acceptable only for PRM, as the Ky values in these treatments were 2 range 0.57 to 0.92), while they exhibited a second order polynomial and moderate correlation with IWUE and WP (R2 range 0.29 to 0.54). Overall, combining RT with plant residue mulching, particularly using the readily available palm residues in sufficient amount is a feasible and sustainable water-saving strategy for enhancing wheat yield and WP in irrigated arid countries, such as Saudi Arabia

Potential Use of Hyperspectral Reflectance as a High-Throughput Nondestructive Phenotyping Tool for Assessing Salt Tolerance in Advanced Spring Wheat Lines under Field Conditions

The incorporation of stress tolerance indices (STIs) with the early estimation of grain yield (GY) in an expeditious and nondestructive manner can enable breeders for ensuring the success of genotype development for a wide range of environmental conditions. In this study, the relative performance of GY for sixty-four spring wheat germplasm under the control and 15.0 dS m−1 NaCl were compared through different STIs, and the ability of a hyperspectral reflectance tool for the early estimation of GY and STIs was assessed using twenty spectral reflectance indices (SRIs; 10 vegetation SRIs and 10 water SRIs). The results showed that salinity treatments, genotypes, and their interactions had significant effects on the GY and nearly all SRIs. Significant genotypic variations were also observed for all STIs. Based on the GY under the control (GYc) and salinity (GYs) conditions and all STIs, the tested genotypes were classified into three salinity tolerance groups (salt-tolerant, salt-sensitive, and moderately salt-tolerant groups). Most vegetation and water SRIs showed strong relationships with the GYc, stress tolerance index (STI), and geometric mean productivity (GMP); moderate relationships with GYs and sometimes with the tolerance index (TOL); and weak relationships with the yield stability index (YSI) and stress susceptibility index (SSI). Obvious differences in the spectral reflectance curves were found among the three salinity tolerance groups under the control and salinity conditions. Stepwise multiple linear regressions identified three SRIs from each vegetation and water SRI as the most influential indices that contributed the most variation in the GY. These SRIs were much more effective in estimating the GYc (R2 = 0.64 − 0.79) than GYs (R2 = 0.38 − 0.47). They also provided a much accurate estimation of the GYc and GYs for the moderately salt-tolerant genotype group; YSI, SSI, and TOL for the salt-sensitive genotypes group; and STI and GMP for all the three salinity tolerance groups. Overall, the results of this study highlight the potential of using a hyperspectral reflectance tool in breeding programs for phenotyping a sufficient number of genotypes under a wide range of environmental conditions in a cost-effective, noninvasive, and expeditious manner. This will aid in accelerating the development of genotypes for salinity conditions in breeding programs

Potential Use of Hyperspectral Reflectance as a High-Throughput Nondestructive Phenotyping Tool for Assessing Salt Tolerance in Advanced Spring Wheat Lines under Field Conditions

The incorporation of stress tolerance indices (STIs) with the early estimation of grain yield (GY) in an expeditious and nondestructive manner can enable breeders for ensuring the success of genotype development for a wide range of environmental conditions. In this study, the relative performance of GY for sixty-four spring wheat germplasm under the control and 15.0 dS m−1 NaCl were compared through different STIs, and the ability of a hyperspectral reflectance tool for the early estimation of GY and STIs was assessed using twenty spectral reflectance indices (SRIs; 10 vegetation SRIs and 10 water SRIs). The results showed that salinity treatments, genotypes, and their interactions had significant effects on the GY and nearly all SRIs. Significant genotypic variations were also observed for all STIs. Based on the GY under the control (GYc) and salinity (GYs) conditions and all STIs, the tested genotypes were classified into three salinity tolerance groups (salt-tolerant, salt-sensitive, and moderately salt-tolerant groups). Most vegetation and water SRIs showed strong relationships with the GYc, stress tolerance index (STI), and geometric mean productivity (GMP); moderate relationships with GYs and sometimes with the tolerance index (TOL); and weak relationships with the yield stability index (YSI) and stress susceptibility index (SSI). Obvious differences in the spectral reflectance curves were found among the three salinity tolerance groups under the control and salinity conditions. Stepwise multiple linear regressions identified three SRIs from each vegetation and water SRI as the most influential indices that contributed the most variation in the GY. These SRIs were much more effective in estimating the GYc (R2 = 0.64 − 0.79) than GYs (R2 = 0.38 − 0.47). They also provided a much accurate estimation of the GYc and GYs for the moderately salt-tolerant genotype group; YSI, SSI, and TOL for the salt-sensitive genotypes group; and STI and GMP for all the three salinity tolerance groups. Overall, the results of this study highlight the potential of using a hyperspectral reflectance tool in breeding programs for phenotyping a sufficient number of genotypes under a wide range of environmental conditions in a cost-effective, noninvasive, and expeditious manner. This will aid in accelerating the development of genotypes for salinity conditions in breeding programs