Influence Of Drought Conditions Research Articles

Influence of drought conditions on yield attributing characters and yield of wheat genotypes

Drought stress remains a major environmental factor which decreases the yield and productivity of most cereals growing worldwide. The research was carried out to assess correlation and path coefficient among 20 bread wheat (Triticum aestivum L.) genotypes. The treatments under drought conditions affected all agronomic traits, and the genotypes showed a significant difference. However, the results from the ambient tunnel were satisfactory, and some interesting observations were made. The present experiment was undertaken to estimate the correlation coefficient between grain yield and different yield contributing characters. The experiment was laid-out with two replications using an alpha lattice design. The study aimed to determine the degree of association between yield and yield attributing characters of drought-tolerant wheat populations using correlation and path analyses. The experiment's results demonstrated a highly significant difference in all the attributes examined between the wheat varieties, and water restriction dramatically reduced those traits. Partitioning of correlation coefficients into direct and indirect effects revealed. strong positive direct effects of spike weight on grain yield under drought-stressed conditions. Spike weight expressed the highest positive correlation (0.696) with grain yield, whereas spikelet per spike showed the lowest positive correlation (0.2) with tiller/m2.

Spatiotemporal Variation in Compound Dry and Hot Events and Its Effects on NDVI in Inner Mongolia, China

In recent decades, frequent compound dry and hot events have posed a great threat to humans and the ecological environment, especially in Inner Mongolia, which has arid and semi-arid characteristics. In this study, monthly temperature and precipitation data from 115 meteorological stations in Inner Mongolia from 1982 to 2020 were used to establish a standardized dry and hot index (SDHI). Theil–Sen median trend analysis, Mann–Kendall test, partial correlation analysis, and stepwise multiple regression models were used to characterize the changes in compound dry and hot events and the normalized difference vegetation index (NDVI) from 1982 to 2020, and the relationship between the SDHI and NDVI was quantitatively evaluated. The results showed that the overall SDHI values in Inner Mongolia showed a significant decrease at a rate of 0.03/year from 1982 to 2020, indicating an increase in the severity of compound dry and hot events. NDVI values showed a significant increasing trend and NDVI showed mutated 2001. Among the grassland vegetation types, SDHI and NDVI trends were more significant in forests, and meadow steppe, desert steppe, and desert were more susceptible to compound dry and hot events, and forests had the greatest severity of compound dry and hot events. The results of the partial correlation analysis showed that the average value of the partial correlation coefficient between the SDHI and NDVI was 0.68, and the area of positive correlation was 84.13%. Spatially, it showed strong response characteristics in the middle and gradual weakening towards the east and west sides. The correlation between NDVI and climatic conditions varied greatly in different vegetation areas. The forest area is most sensitive to the influence of temperature, and the desert steppe area is most affected by compound dry and hot events. The overall vegetation growth in Inner Mongolia was most affected by temperature conditions, followed by compound dry and hot conditions, and the influence of drought conditions was the least significant. The results of the relative importance analysis confirmed this. The research results provide a more detailed understanding of compound dry and hot events in arid and semi-arid regions and useful insights and support for ecological protection.

Performance of different drought indices for agriculture drought in the North China Plain

The Palmer drought severity index (PDSI), standardized precipitation index (SPI), and standardized precipitation evapotranspiration index (SPEI) are used worldwide for drought assessment and monitoring. However, substantial differences exist in the performance for agricultural drought among these indices and among regions. Here, we performed statistical assessments to compare the strengths of different drought indices for agricultural drought in the North China Plain. Small differences were detected in the comparative performances of SPI and SPEI that were smaller at the long-term scale than those at the short-term scale. The correlation between SPI/SPEI and PDSI considerably increased from 1- to 12-month lags, and a slight decreasing trend was exhibited during 12- and 24-month lags, indicating a 12-month scale in the PDSI, whereas the SPI was strongly correlated with the SPEI at 1- to 24-month lags. Interestingly, the correlation between the trend of temperature and the mean absolute error and its correlation coefficient both suggested stronger relationships between SPI and the SPEI in areas of rapid climate warming. In addition, the yield–drought correlations tended to be higher for the SPI and SPEI than that for the PDSI at the station scale, whereas small differences were detected between the SPI and SPEI in the performance on agricultural systems. However, large differences in the influence of drought conditions on the yields of winter wheat and summer maize were evident among various indices during the crop-growing season. Our findings suggested that multi-indices in drought monitoring are needed in order to acquire robust conclusions.

English

Drought conditions are the major constraint to the early establishment of Quercus suber species. However, drought responses of this species depend on provenances. The objective of this study was to obtain more comprehensive knowledge on the influence of drought conditions on the response of Q. suber L. seedlings originating from Algeria. Soil water status in soil (SWC) and relative water content (RWC) in leaves, morphological parameters for growth evaluation and physiological parameters, and ectomycorrhization were evaluated in two plots of seedlings: watered (W) and none watered (NW). Ten weeks of water starvation induced a reduction in RWC, ectomycorrhization rate and height and diameter growth of none watered seedlings. Under drought conditions, both soluble sugars and proteins were enhanced while polyphenols and %N decreased. The reduction of soil water content was negatively correlated with carbon isotope discrimination. The survival of the seedlings under these drought conditions was due to two strategies: osmotic adjustment through soluble sugars and proteins accumulations in leaves and an increase in carbon discrimination which enhances the water use efficiency (WUE). Key words: Quercus suber, growth, drought, ectomycorrhization, pigments, sugars, starch, plyphenols, δ13C.

On the influence of drought conditions upon the growth of soybean plants, with special regards to those upon flowering. (preliminary report)

In this experiment, it was tested how the flowering of soybean plants was influenced by the different contents of soil moisture, which were artificially kept 30% (A plot) and 70% (C plot) during the whole course of the growth and 30% during the flowering period (B plot). A local variety named Akazaya was used for this purpose. The results obtained were as follows : (1) The vegetative growth of plants grown under the drought conditions (A & B plots) was rather reduced in comparison to that of plants grown under normal (C plot) ; the decrement of numbers of both nodes and branches which bore flowers was striking in A plot. (2) Total number of flowers was therefore decreased by the treatments (A & B plots) : while it was found that the ratio of flowers in main stem to those in branches was always the same (1 : 3); notwithstanding those treatments. (3) The reduction of numbers of flowers in lower nodes was remarkable under the severest drought condition (A plot). Then the flowering in such a plant was found in nearly a rhomb shape In contrast to A plot, the shape was a triangle in normal plants (C plot). And in B plot, it took a middle shape between A and c . In short the reduction of flowers caused by the drought was due to that in lower nodes. (4) Days from the germination to the beginning of blooming were undistinguishable among three plots. But, under the constant drought condition (A plot), the blooming date seemed to be significantly postponed in both upper and lower nodes. (5) The duration of flowering period was reduced by the treatments ; especially the reduction occured evidently in upper and lower nodes of plants grown under the constant drought condition (A plot). (6) Concerning all stems examined, the influences of the treatments were almost unrecognizable in both sixth and seventh nodes. Because all flowers borne on these nodes were nearly the same in number in all plots.