Imposed Moisture Stress Research Articles

Elevated Southern Hemisphere moisture availability during glacial periods.

Late Pleistocene ice-age climates are routinely characterized as having imposed moisture stress on low- to mid-latitude ecosystems1-5. This idea is largely based on fossil pollen evidence for widespread, low-biomass glacial vegetation, interpreted as indicating climatic dryness6. However, woody plant growth is inhibited under low atmospheric CO2(refs. 7,8), so understanding glacial environments requires the development of new palaeoclimate indicators that are independent of vegetation9. Here we show that, contrary to expectations, during the past 350 kyr, peaks in southern Australian climatic moisture availability were largely confined to glacial periods, including the Last Glacial Maximum, whereas warm interglacials were relatively dry. By measuring the timing of speleothem growth in the Southern Hemisphere subtropics, which today has a predominantly negative annual moisture balance, we developed a record of climatic moisture availability that is independent of vegetation and extends through multiple glacial-interglacial cycles. Our results demonstrate that a cool-moist response is consistent across the austral subtropics and, in part, may result from reduced evaporation under cool glacial temperatures. Insofar as cold glacial environments in the Southern Hemisphere subtropics have been portrayed as uniformly arid3,10,11, our findings suggest that their characterization as evolutionary or physiological obstacles to movement and expansion of animal, plant and, potentially, human populations10 should be reconsidered.

EFFECTS OF DROUGHT STRESS ON GROWTH AND YIELD PARAMETERS OF ZEA MAYS- A COMPREHENSIVE REVIEW

Maize serves as an important food source for human and livestock populations and its demand is heightening in response to the ever-increasing global population. Maize uses a total of 350-450 mm of water during its lifetime to complete its growth and development. However, as a result of global climate change and increased human activity, a significant portion of the Earth’s land is suffering from drought, leading to frequent periods of dryness that hamper the production of maize. This review article recounts the consequences of imposing moisture stress on various developmental stages, phenology, morphology, harvest, and yield-attributing characteristics of the maize crop. To form this review article, research papers expatiating on the consequences faced by maize crops in response to moisture stress were retrieved to gain a thorough understanding of the subject. Drought stress affected both vegetative and reproductive growth stages of the maize plant with significant alterations in seed germination, biomass accumulation, days to anthesis and silking, pollen number, kernel number, kernel weight, grain yield, nutrient uptake, and soluble proteins. The result has shown a decline in the yield of maize by 70% in response to moisture stress imposed by drought conditions. The development of drought-resistant lines and irrigation facilities is thus expected to salvage crops and farmers from an impending crisis of drought spells brought about by climate change.

Associations between pod yield and it’s contributing traits in advanced peanut lines as influenced by imposed moisture stress

Aim: Assessment of correlation between yield and its contributing traits in groundnut under terminal drought stress Experimental Design: Randomized complete block design (RCBD) design replicated twice Location and duration of the study: The College of horticulture, Hiriyur during rabi 2016-17Methodology: Forty genotypes of groundnut comprising advanced breeding lines and existed cultivars were subjected to field evaluation under irrigated and imposed end-of-season drought stress. The moisture stress was imposed at 90 DAS for 20 days by withholding irrigation to drought stress block. However, the irrigated trail was provided with regularly recommended irrigations. Observations on morphological, yield and its contributing traits were recorded on randomly sampled five plants per entry per replication in both the environments at different stages of the crop growth cycle. The resulted mean data was subjected to statistical analysis using Genstat 14.1 software.Results: Results revealed that pod yield per plant showed a significant positive correlation with the number of mature pods per plant, number of immature pods per plant, number of pods per plant, number of kernels per plant, kernel yield per plant, fresh weight of seedling and harvest index under imposed end-season drought stress.Conclusion: It can be concluded that these traits should be given due importance while practicing selection for increasing yield under drought stress and also in development of high yielding drought tolerant genotypes in groundnut.

Responses of above and below ground traits of 10 accessions of Triticum boeoticum to non-stress and imposed moisture stress conditions

Triticum boeoticum wild wheat is a remarkable gene pool to environmental stress resistance. It is one of the most valuable species of the Triticeae tribe for improving wheat cultivars to moisture-stress. This research was carried out to assess the changes and responses of different traits of 10 accessions of Triticum boeoticum under non-stress and imposed moisture stress conditions in 2015 and 2016. Most traits were significantly affected by accession (A), water treatments (WT), and A×WT interactions. The accessions showed a high-level of genetic diversity for all traits, except peduncle weight. The accessions Tb5 and TB3 with the highest amount of economic yield per plant (EYPP) and water use efficiency (WUE), were less affected by the imposed moisture stress, while accession Tb6 with the maximum amount of water use (WU), main root length (MRL) and some phenological traits, were the most affected. The traits of WUE and main stem weight (MSTW) showed the highest and the traits of excised leaf water retention (ELWR), MRL and WU showed the lowest alignment with EYPP, respectively. The ability of producing assimilates (by increasing biological yield per plant and MSTW) and the ability of faster assimilates-remobilization into grains (by increasing harvest index and WUE), has been a neglected aspect of breeding wheat program under drought stress. In other words, the ability of a genotype to produce more assimilates and allocate it to grains (by increased BYPP and WUE, respectively) instead of belowground-traits, will result to increase EYPP. For example, the Tb6 ecotype, due to the allocation of more assimilates to underground parts, had little grain yield. While the traits of WUE, BYPP, seed number per main spike, seed weight per main spike (SWPMS) and main spike weight (MSPW) showed a positive and significant (P<0.01) correlation to EYPP, the traits of ELWR, MRL, day to heading and day to anthesis, had a negative and significant (P<0.05) correlation with yield. Generally, a high amount of WUE, MSTW, SWPMS, MSPW and peduncle weight; with a low amount of ELWR, phenological traits (except grain filling period), MRL, WU, and root to shoot dry weight ratio (RDWSDW) were suggested for the improvement of grain yield. SWPMS and MSPW were two main-components of grain yield in the favorite accessions (Tb5 and Tb3). Tb5 and Tb3 may have value for breeding wheat better adapted to moisture stress conditions in future.

Evaluation of groundnut (Arachis hypogaea L.) varieties for drought tolerance under imposed moisture stress conditions

A field experiment was conducted to study growth and yield of groundnut as influenced by moisture stress imposed at different growth stages using rainout shelters under rainfed conditions during kharif, 2015-16 at Agricultural Research Station, Ananthapuramu of Andhra Pradesh. The experiment waslaid out in a split plot design with four main plot treatments viz., M1: Imposing moisture stress from 30-50 DAS (flowering to pegging), M2: Imposing moisture stress from 50-70 DAS (pegging to pod formation), M3 : Imposing moisture stress from 70-90 DAS (pod filling to maturity) and M4 : Moisture stress free condition and the subplots comprised of 5 varieties viz., K-6, K-9, Anantha, Dharani and Harithandhra. Moisture stress from 70-90 DAS (Pod filling to maturity) recorded highest pod yield reduction followed by stress from 50-70 DAS (pegging to pod formation) and 30-50 DAS (flowering to pegging) compared to stress free condition and thus suggesting that pod filling to maturity stage is the most critical stage. Among varieties K6, Harithandra and Anantha recorded pod yield reduction of 54.0, 53.7 and 49.3 per cent, respectively. K9 and Dharani recorded 39 and 39.7 per cent pod yield reduction. The study indicated that K9 and Dharani are drought tolerant groundnut varieties.

Peanut genotypes with high chlorophyll content and low leaf temperature are preferred in breeding program for drought prone areas

An understanding of drought stress and water use in relation to plant growth is of importance for sustainable agriculture. Groundnut genotypes respond differently to different stages of drought stress. The aim of this research was to study the response of groundnut genotypes to different stages of moisture stress. Seven groundnut genotypes (Samnut 25, Kwankwaso, Maibargo, Samnut 23, Samnut 24, EX dakar, and Samnut 21) and three water supply (80% field capacity, 40% field capacity and without irrigation) with three replications were used for the study. The water stress was imposed after 14 days of initial growth of the plants and was maintained by using TDR to check the moisture level every three days. Significant differences was observed between the genotypes for leaf temperature and chlorophyll content at two weeks after imposition of moisture stress. Also, significant differences was observed between the moisture levels for all variable measured except for the chlorophyll content before imposing moisture stress. An interaction effect was observed between the genotypes and water stress for root length and Mai Bargo produced the highest root length when terminal drought was simulated. The research shows that the genotypes have varying responses to leaf temperature and chlorophyll content and will consistently vary under different moisture stresses. Therefore, genotypes identified with high chlorophyll content and low leaf temperature can be selected as parents for further breeding program or introduction into drought prone areas.

Morpho-physiological and proteomic responses of Aegilops tauschii to imposed moisture stress

Moisture stress is the most important limitation of wheat production in the worldwide. Among the tribe Triticeae, Aegilops tauschii is one of the most valuable gene sources of resistance to abiotic stresses. In order to identify the most tolerant accession to moisture stress, and to understand its adaptive mechanisms at the molecular level, the present experiment was carried out on ten Ae. tauschii accessions under normal (95% soil pot capacity) and moisture stress (45% soil pot capacity) conditions. At the start of the heading time, the expanded flag leaves of treated and untreated plants were sampled for two-dimensional electrophoresis (2-DE) based on proteomics approach. A19 accession was less affected by the imposed moisture stress; therefore, it was used for the proteomics experiment. Among 252 protein spots which were reproducibly detected in each given 2-DE gels, 25 spots showed significant differences between the two moisture treatments; 17 spots were upregulated and 8 spots were downregulated. The identified proteins by MALDI-TOF/TOF, were allocated to seven functional protein groups, which were mainly involved in photosynthesis/respiration (28.5%), carbohydrate metabolism (14.2%), energy metabolism (7.1%), chaperone (14.2%), protein translation and processing (14.2%), repair and stability of the genome (7.1%) and unknown function (14.2%). We report this for the first time that RMI2 protein (in the group of repair and stability of the genome) was significantly changed in wheat in response to moisture stress. We believe that, the identified proteins could play important roles in acclimation and tolerance to moisture stress and provide the genetic pathways for improving tolerance to moisture stress in wheat.

English

The impact of drought stress and foliar nutrition on dry matter accumulation in different parts of soybean plant was studied at Dryland Farm of S.V. Agricultural College, Regional Agricultural Research Station, Acharya N.G. Ranga Agricultural University, Tirupati during rabi season, 2014-15. The experiment was conducted as a Randomized Block Design with three replications. In this research, Groundnut crop was imposed to mid-season moisture stress from 45 DAS to 75 DAS (pod formation to pod filling stage). Treatments included Foliar application of chemical nutrients (8 treatments) along with two checks (one control irrigated and one control stress) were imposed at 60 days after sowing (15 days after imposing moisture stress). The results revealed that, significant variations for morphological, physiological, drought tolerance, biochemical and yield attributes were observed. Among the foliar spray treatments at harvest, the foliar spray treatment KNO3 @ 0.5% recorded significantly higher stem, leaf and pod dry weight and also total drymatter partitioning followed by NPK -19:19:19 @ 0.5% and KCl @ 1% compared to control stress treatment. Among the foliar spray treatments NPK- 19:19:19 @ 0.5%, at 75 and 90 DAS was found to be superior in increasing the LAI followed by KNO3 @ 0.5% and KCl @ 1%.

Evaluation of sugarcane genotypes for high water use efficiency and thermostability tolerance under imposed moisture stress at formative stage

Fourteen sugarcane genotypes were screened for traits contributing to high water use efficiency (WUE) and temperature tolerance in a field experiment by imposing moisture stress at formative phase i.e. 40 DAP to 120 DAP (days after planting). WUE was measured using surrogate methods viz., SPAD chlorophyll meter readings (SCMR), specific leaf area (SLA) and thermostability was quantified by measuring membrane relative injury percentage on 20 days (60 DAP) and 80 days (120 DAP) after imposing moisture stress (DAIS). Among the fourteen genotypes, four genotypes viz., 97 R 129, 92 V 104, CO (O) 061 and CO 6907 showed low SLA and higher SCMR values, which indicates higher water use efficiency. However, higher thermostability was recorded in 92 V 104 and CO 6907 genotypes only. Hence, the 92 V 104 and CO 6907 genotypes having both WUE and temperature tolerance traits can be used as donar parents in breeding programmes. SCMR, SLA, relarive injury per cent can be used as surrogate methods for measurement of WUE and temperature tolerance in sugarcane and can be used as selection traits in breeding programme for developing drought tolerant genotypes.

Moisture Stress Effects on the Absorption, Translocation, and Metabolism of Haloxyfop in Johnsongrass (Sorghum halepense) and Large Crabgrass (Digitaria sanguinalis)

Glasshouse studies were undertaken to determine the effect of imposed moisture stress on the phytotoxicity of haloxyfop; the absorption, translocation, and metabolism of14C-haloxyfop; and14C-photoassimilate partitioning in johnsongrass and large crabgrass. Following foliar applications of haloxyfop at 30 and 25 g ai ha–1to large crabgrass and johnsongrass, respectively, control 15 days after treatment was 92% for nonstressed plants and less than 12% for water-stressed plants. Foliar absorption of14C-haloxyfop was reduced by moisture stress 1, 3, 5, and 24 h after treatment (HAT) in large crabgrass and 1, 3, 5, 48, and 72 HAT in johnsongrass. Regardless of stress treatment, absorption in both species reached a maximum by 24 HAT. Translocation of the radiolabel from the treated leaf to plant parts above and below the node of the treated leaf was inhibited by moisture stress in large crabgrass and johnsongrass at all harvest intervals beginning 5 and 24 HAT, respectively. Metabolism of14C-haloxyfop was not altered by moisture stress. Fixation of14CO2and subsequent distribution of the14C-photoassimilates were reduced by moisture stress. Decreases in photoassimilate translocation were similar to reductions in14C-haloxyfop translocation. Moisture stress reduced the phytotoxicity of haloxyfop in the two grasses, and the reduced activity of haloxyfop appeared to be partially related to changes in herbicide absorption and translocation.

Moisture Stress Effects on Absorption and Translocation of Four Foliar-Applied Herbicides

Laboratory experiments with14C-herbicides were conducted with grain sorghum as an indicator species to determine the effects of imposed moisture stress on absorption, precent recovery, and acropetal and basipetal translocation of the butyl ester of fluazifop, the methyl ester of haloxyfop, the ethyl ester of quizalofop, and sethoxydim. Haloxyfop was the only herbicide where recovery decreased between the 3-and 48-h interval. All plants absorbed more of the herbicide at the 48-h interval than at the 3- or 6-h interval under both stressed and non-stressed conditions. Increased drought stress caused more acropetal movement with fluazifop and sethoxydim and less acropetal movement with quizalofop at the 3-h interval. Basipetal transloation, although different among herbicides, responded similarly to imposed moisture stress, which decreased basipetal translocation approximately 19%.

Environmental Influences on Yield and In Vitro True Digestibility of Warm‐Season Perennial Grasses and the Relationships to Fiber Components1

AbstractIn recent years climatic fluctuations have been increasingly associated with seasonal variation in yield and quality of forage crops. Although considerable information is available concerning environmental influences on yield and quality of many temperate and tropical grasses, very little is known about these relationships in the major grasses grown in the southern U.S.A. The objectives of this study were to determine the relative influences of temperature (T) and photon flux density (L) on dry matter yield (DMY) and in vitro true digestibility (IVD) of four warm‐season perennial grasses grown at two soil moisture levels and to relate the differences in IVD to fiber component concentrations. Coastal and common hermudagrass [Cynodon dactylon (L.) Pers.], Pensacola hahiagrass (Paspalurn notatum Flugge), and dallisgrass (P. dilatatum Poir.) were grown in an artificial growth medium at 4 day/night temperatures (35/24, 32/21, 29/18, 26/15 C), four photon Aux densities (1,050, 840, 630, 420 µEm−2 sec−1 PAR) and two soil moisture levels in growth cabinets. After 14 and 21 days regrowth, DMY and IVD were measured. Regression equations were developed to predict DMY and IVD as functions of T and L at each soil moisture level and regrowth period.The study clearly showed that DMY of all grasses increased with increasing T and L. The imposed moisture stress sharply reduced DMY of dallisgrass (DAL) hut not of the other grasses. In all grasses IVD consistently decreased as T increased, resulting in maximum IVD at the lowest T. The effect of L on IVD ranged from positive to negative, depending on the grass and T. Maximum IVD values occurred at the high soil moisture (HM) level after 14 days regrowth. At the HM level maximum IVD of Coastal bermudagrass (COA), common hermudagrass (COM), and Pensacolabahia grass (BAH), respectively, was 5.7, 4.9, and 3.6 percentage units higher after 14 than after 21 days regrowth. In DAL at the HM level and in all grasses at the low soil moisture level, these differences due to age were only about one percentage unit or less. The Paspalum spp. averaged about seven percentage units higher in IVD than the Cynodon spp. Significant (P ≤ 0.01) negative correlations were obtained between IVD and previously reported concentrations of acid detergent fiber (ADF), cellulose, permaganate lignin (LIG), and silica in all grasses and concentrations of neutral‐detergent fiber in COA and COM. Although correlation coefficients were ≤ 0.50, hemicellulose concentration and IVD were positively correlated in all grasses. Strongest correlations were obtained between IVD and concentrations of ADF and LIG.