Assessing the large-scale plant–water relations in the humid, subtropical Pearl River basin of China

Vegetation interacts closely with water resources. Conventional field studies of plant–water relations are fundamental for understanding the mechanisms of how plants alter and adapt to environmental changes, while large-scale studies can be more practical for regional land use and water management towards mitigating climate change impacts. In this study, we investigated the changes in the total water storage (TWS), aridity index (AI) and vegetation greenness, productivity, and their interactions in the Pearl River basin since April 2002. Results show an overall increasing trend of vegetation greenness and productivity, especially in the middle reaches where TWS also increased. This region dominated by croplands was identified as the hot spot for changes and interactions between water and vegetation in the basin. Vegetation was more strongly affected by TWS than precipitation (P) at both the annual and monthly scales. Further examination showed that the influence of TWS on vegetation in dry years was stronger than wet years, while the impact of P was stronger in wet years than dry years; moreover, vegetation productivity responded slower but stronger to atmospheric dryness in dry years than wet years. The lag effects resulted in nonlinearity between water and vegetation dynamics. This study implies that vegetation in the basin uses rainwater prior to water storage until the soil becomes dry, and their dynamics indicate that vegetation development is subject to water availability, and that vegetation is not dominant in reducing water availability.

Role of Selenium in Regulation of Plant Antioxidants, Chlorophyll Retention and Osmotic Adjustment under Drought Conditions: A Review

Environmental change is ascending as one of the most unpredictable issue, the effects of which are observable as rise in the onset of regular abiotic stresses like no or irregular precipitation, ascend in worldwide normal temperature, floods and so on. Among all the abiotic stresses, drought stress has become a sector of interest for decades. Drought stress can be chronic in locations with low water accessibility or irregular precipitation during the time of plant development consequently decreasing its growth and yield through its impact on plant photosynthetic rate, increased load of reactive oxygen species, changes in plant water relations and so on. A great deal of examination has been done to study the varieties of changes in the plants at the morphological, physiological and cellular level to identify the methodologies for enhancing plant drought resistance. In this regard "selenium" (Se) is considered exceptionally significant for improving plant growth and development. Spraying drought stressed plants or pre-treating the seeds with low dosage of Se have been shown to be associated with upgraded plant drought resistance. The present study is aimed to frame a review on the regulation of plant defense system, chlorophyll retention and plant water relations so as to provide comprehensive understanding into the changes caused by the application of Se which inturn are liable for improved plant drought tolerance.

Chloride Changes Soil–Plant Water Relations in Potato (Solanum tuberosum L.)

There is evidence that chloride (Cl―) can lead to both an improved hydration and water use efficiency in plants due to its osmotic properties. The potato crop is widely assumed to be sensitive to Cl―. This is based on studies which found tuber yield or tuber starch reductions following a Cl― fertilization. However, there are also contradictory reports which could not find any detrimental effect of Cl― fertilization on potato plant development. As potato is inefficient in the use of water, we aimed to test if it is possible to improve the hydration status of potato without reducing tuber yield and dry matter by means of Cl― fertilization. We conducted a pot experiment with four different Cl― doses and investigated soil–plant water relations, biomass, tuber yield and dry matter development. Our findings deliver an indication that the potato crop is much less sensitive to Cl― than previously assumed and, more importantly, that a Cl― supply can indeed improve the potato shoot water status. This happened without impairing tuber yield and dry matter. Since potato is very sensitive to drought stress, we assume that Cl― fertilization is a promising measure to improve the drought resilience of potato.

MULTI-SCALE TIME SERIES ANALYSIS OF EVAPOTRANSPIRATION FOR HIGH-THROUGHPUT PHENOTYPING FREQUENCY OPTIMIZATION

This work is undertaken considering the significance of functional phenotyping (primarily measured from continuous profiles of plant-water relations) for crop selection purposes. High-Throughput Plant Phenotyping (HTPP) platforms which largely employ state-of-the-art sensor technologies for acquisition of vast amount of field data, often fail to efficiently translate sensor information into knowledge due to the major challenges of data handling and processing. Hence, it is imperative to concurrently find a way for dissociating noise from useful data. Additionally, another important aspect is understanding how frequent should be the data collection, so that information is maximized. This paper presents a novel approach for identifying the optimal frequency for phenotyping evapotranspiration (ET) by assimilating results from both time series forecast as well as classification models. Thus, at the optimal frequency, plant-water relations can not only be desirably predicted but genotypes can also be classified based on the characteristics of their ET profiles. Consequently, this will aid better crop selection, besides minimizing noise, redundancy, cost and effort in HTPP data collection. High frequency (15 min) ET time series data of 48 chickpea varieties (with considerable genotypic diversity) collected at the LeasyScan HTPP platform, ICRISAT is used for this study. Time series forecast and classification is performed by varying frequency up to 180 min. Multiple performance measures of time series forecast and classification are combined, followed by implementation of entropy theory for sampling frequency optimization. The results demonstrate that ET time series with a frequency of 60 min per day potentially yield the optimum information.

Routes to Roots: Direct Evidence of Water Transport by Arbuscular Mycorrhizal Fungi to Host Plants

Arbuscular mycorrhizal fungi (AMF) form symbiotic associations with 80% of surveyed land plant species and are well-recognized for accessing and transferring nutrients to plants1. Yet AMF also perform other essential functions, notably improving plant-water relations2. Some research attributes the role of AMF in plant-water relations solely to enhancing plant nutrition and osmoregulation for plants partnered with AMF3,4,5, while indirect evidence suggests AMF may transport water to plants1,6,7. Here, we used isotopically-labeled water and a fluorescent dye to directly track and quantify water transport by AMF to plants in a greenhouse experiment. We specifically assessed whether AMF can access water in soil unavailable to plants and transport it across an air gap to host plants. Plants grown with AMF that had access to a physically separated 18O-labeled water source transpired twice as much, and this transpired water contained three times as much label compared to plants with AMF with no access to the separated labeled water source. We estimated that water transported by AMF could explain 46.2% of the water transpired. In addition, a fluorescent dye indicated that water was transported via an extracytoplasmic hyphal pathway.