M. Maheswari

Crop Stress and its Management: Perspectives and Strategies

Edited by B. Venkateswarlu, A.K. Shanker, C. Shanker, and M. Maheswari. Springer, 11 West 42nd St., New York, NY 10036. 2011. Hardcover, 628 pp.

Overview of Plant Stresses: Mechanisms, Adaptations and Research Pursuit

196.34. ISBN 978-94-007-2219-4. In plants, biotic and abiotic stresses can limit crop growth and development and consequently the yield. An intricate plant response to diff erent types of stresses hampers notable progress in improving stress tolerance. The book Crop Stress and Its Management: Perspectives and Strategies is an excellent attempt to provide a better understanding of stress management in plants. The book is comprised of 19 chapters, highlighting physiological, anatomical, and biochemical changes due to a particular stress and its management. The opening chapter provides an excellent overview regarding stress in terms of its mechanism, plant response to diff erent stress types (biotic and abiotic stresses), and conventional and molecular techniques to improve the tolerance level. The authors comprehensively describe the operational strategy steps as: transcript profi ling, proteome analysis, studying the metabolism, and analyzing the entire data in bioinformatics techniques to recuperate the stress tolerance. Chapter 2 highlights the importance of dryland agriculture from the food security perspective because a substantial portion of cereal crops are being cultivated on rainfed land. The authors sketch out the dryland geographic zones on the face of the earth and portray climate changes in the area through the course of time. Production challenges and strategies to mitigate these challenges are briefl y described to enhance the crop resilience against the climate change. A comprehensive description of adaptation mechanisms in plantation crops is presented in Chapter 3. Mechanisms and types of abiotic e.g. drought (anatomical, physiological, biochemical), temperature, radiation, nutrition and pollution; and biotic adaptations e.g. constitutive and inducible defense against pathogenesis, allelopathy, and defense against herbivory, are illustrated in detail. Stress management strategies are explained as: genetic improvement and selection, as well as molecular breeding; better crop management with improved agronomic practices; and biological control. Cell physiology to sense and signal a particular stress is described in Chapter 4. The functional mechanisms to avoid, escape, and/or tolerate drought stress; role of sucrose non-fermenting 1-related protein kinases (SnRK); and stress response of quantitative trait loci to high and low temperatures have been mentioned. Machine learning (ML) algorithms, the idea of making intelligent data based decisions for mapping QTLs for complex traits, assigning the inbred lines in diff erent heterotic groups, and/ or genomewide selection is introduced in Chapter 5. The author advocates that high generalization capabilities and distribution of free properties of ML provide better estimation compared to contemporary computational approaches. Chapter 6 features heat stress mechanisms in rice by elaborating physiological, anatomical, and biochemical changes in the phenology and its adaptive response to cope with stress. A combination of conventional and nonconventional techniques (marker-assisted breeding, transcriptome analysis, transgenic rice cultivars with heat shock proteins) along with enhanced fertigation is advocated for higher yields under stress. In Chapter 7 the authors describe the complexity related to drought phenotyping, timing of drought episodes in relation to plant growth stage, high intra-site variability, and strong genotype environment interactions. Hence, authors suggest the use of molecular-assisted genetic improvements and induction of phenotype-associated markers for a rapid and ensuing improvement for

Model and Scenario Variations in Predicted Number of Generations of Spodoptera litura Fab. on Peanut during Future Climate Change Scenario

Biotic and abiotic stresses in crops are a major hurdle in attaining potential yield worldwide. Finding an approach to sustain high yields of crop plants under biotic and abiotic stresses is an important goal of agriculture researchers and stakeholders alike. Among the abiotic stresses, drought, salinity, temperature and heavy metal accumulation are the major environmental stresses, which adversely affect plant growth and productivity. In addition, biotic stresses primarily, plant diseaseses are a significant constraint to the production of about 25 important food and fiber crops. Changing climate compounds these adverse effects of stresses on crops. To cope with biotic and abiotic stress it is of paramount significance to understand plant responses to these stresses that disturb the homeostatic equilibrium at cellular and molecular level in order to identify a common mechanism for multiple stress tolerance at least in the case of abiotic stresses. An integrated systems approach is essential in the study of complex quantitative traits governing tolerance to multiple biotic and abiotic stresses. A detailed account of specially abiotic stresses and combating strategies to effectively counter them are discussed in this chapter.

Physiological and Biochemical Basis of Extended and Sudden Heat Stress Tolerance in Maize

The present study features the estimation of number of generations of tobacco caterpillar, Spodoptera litura. Fab. on peanut crop at six locations in India using MarkSim, which provides General Circulation Model (GCM) of future data on daily maximum (T.max), minimum (T.min) air temperatures from six models viz., BCCR-BCM2.0, CNRM-CM3, CSIRO-Mk3.5, ECHams5, INCM-CM3.0 and MIROC3.2 along with an ensemble of the six from three emission scenarios (A2, A1B and B1). This data was used to predict the future pest scenarios following the growing degree days approach in four different climate periods viz., Baseline-1975, Near future (NF) -2020, Distant future (DF)-2050 and Very Distant future (VDF)—2080. It is predicted that more generations would occur during the three future climate periods with significant variation among scenarios and models. Among the seven models, 1–2 additional generations were predicted during DF and VDF due to higher future temperatures in CNRM-CM3, ECHams5 & CSIRO-Mk3.5 models. The temperature projections of these models indicated that the generation time would decrease by 18–22% over baseline. Analysis of variance (ANOVA) was used to partition the variation in the predicted number of generations and generation time of S. litura on peanut during crop season. Geographical location explained 34% of the total variation in number of generations, followed by time period (26%), model (1.74%) and scenario (0.74%). The remaining 14% of the variation was explained by interactions. Increased number of generations and reduction of generation time across the six peanut growing locations of India suggest that the incidence of S. litura may increase due to projected increase in temperatures in future climate change periods.

Differential response of antioxidative enzymes to various abiotic stresses in Pennisetum glaucum seedlings

Effects of extended and sudden heat stress on various physiological and biochemical processes have been investigated in ten inbred lines of maize (Zea mays L.) at seedling stage. Among the various parameters studied, a significant decrease was observed in membrane stability, chlorophyll fluorescence and chlorophyll concentration under extended heat stress and sudden heat shock in sensitive genotypes which indicated their susceptibility to high temperature. However, heat tolerant genotypes exhibited less impact on these parameters which could be attributed to lesser oxidative stress injury. The free radical scavenging system in heat tolerant genotypes was observed to be better established as compared to heat sensitive genotypes. These findings suggested that the genotypes which performed better both under extended and sudden heat stress conditions could be partly due to their superior ability to cope up with oxidative damage caused by heat stress in maize.

Effect of Climate on Productivity of Pigeonpea and Cotton in Andhra Pradesh – A Panel Data Regression

Antioxidative enzyme activities and their isozyme patterns under water-deficit, salinity, high and low temperature stresses were studied in the seedlings of Pennisetum glaucum (L.) R.Br. It was observed that under water-deficit stress glutathione reductase (GR) was the key enzyme while in case of high temperature stress, GR along with catalase played a major role. Superoxide dismutase was found to be the main enzyme under low temperature stress. Co-ordinated higher expression of all the antioxidative enzymes was observed under salt stress. This study revealed the operation of different enzymatic antioxidative mechanisms under various abiotic stresses that will aid in understanding the metabolic basis of stress tolerance in pearl millet.

SUNFLOWER TRAITS RESPONSE TO ELEVATED CO2 LEVELS UNDER COOL AND WARM SEASON CONDITIONS

This paper was attempted to examine the effect of temperature and rainfall on the productivity of two important crops-pigeonpea and cotton in Andhra Pradesh following panel data regression approach. Using the district level time series data, the yield of each of these two crops was regressed on maximum temperature during kharif, rainfall quantity and number of rainy days for the period 1990–2002, in a one-way and two-way fixed effect models of panel regression using Least Squares Dummy Variable Method. Comparison of district specific effects revealed statistically significant differences between districts in case of pigeonpea. The response coefficients for rainfall and number of rainy days were found significant at 5 per cent level. A positive impact on yield of pigeonpea at the rate of 1.9 kg/ha was observed for a 10 mm rise in rainfall. The number of rainy days was found to have a significant negative relationship with yield. In case of cotton, half of the major cotton growing districts differed significantly in mean yield levels. A significant reduction in yield at a rate of 13 kg/ha for every 1°C rise in the maximum temperature was observed. The yield of cotton was found to increase by 0.7 kg/ha for every 10 mm increase in the rainfall.

Influence of water defict at vegetative, anthesis and grain filling stages on water relation and grain yield in sorghum

SUMMARY A study was conducted in the Open Top Chambers (OTCs) to assess the influence of cool and warm season conditions on the response of sunflower (KBSH-1) to two elevated CO2 levels (550 and 700 ppm) and compare them with the response to an ambient level (390 ppm). The effect of elevated CO2 levels on biomass accumulation, seed yield and yield components were quantified in two seasons. Apart from the main effects of CO2 and different seasons, a significant interaction effect between CO2 levels and seasons was also observed. The CO2 levels differed significantly in influencing biomass accumulation, seed yield and number of seeds. Four Principal Components (PC) based on PC analysis explained about 85% of the variability in the response of traits influenced by CO2 levels in winter and summer seasons. In order to predict total dry weight, seed yield and harvest index obtained in winter and summer seasons, regression models of these variables were also calibrated and used through PC scores of different components. The analysis indicated that significant predictions could be made at ambient level with 550 ppm, compared to 700 ppm of CO2 level. The plant traits with a significantly higher loading of more than ± 0.70 on PCs were identified and have been recommended for future research in genetic improvement of sunflower, taking into account the change of climate due to elevated CO2 and temperature levels.