Pre-flowering Stage Research Articles

Analysis of Maize Photosyntheis Parameters and Whole Plant Oxidative Damage Under Long-term Drought

We test if maize maintain yield under long-term drought throught improvement of photosyntheis (A) coupled with up-regulation of the antioxidant system induced by increase in levels of abscisic acid (ABA). Four maize genotypes with constrasting drought tolerance: BRS1010 and 2B710 (sensitive) and DKB 390 and BRS1055 (tolerant) in two soil water levels, field capacity (FC) and water deficit (WD) were used. WD was applied at the pre-flowering stage for 12 days, and oxidative damage was measured as malondialdehyde (MDA) accumulation in whole plant. Plants from tolerant genotypes DKB390 and BRS1055 showed higher A and had no signal of oxidative damage compared to sensitive genotypes 2B710 and BRS1010 under WD, resulting in a higher yield attributes. For our surprising, it was dissociated from up-regulation of the antioxidant system ABA-mediated. In turn, plants from two sensitive genotypes under WD showed compared to FC consistent reduction of A due to mesophyll conductance (gm) limitation. Only WD plants from sensitive genotype BRS1010 presented leaf ABA levels increased related to its counterparts under FC; however, due to the inactivation of catalase activity the oxidative damage control was not effective, resulting a hardly MDA acumulation in both leaves and roots. The maize tolerance under long-term drought is linked to scape of gm decline.

Stage specific upregulation of antioxidant defence system in leaves for regulating drought tolerance in chickpea

Leaf is one of the early sensors for the drought stress and is important to study drought tolerance mechanism. Activities of antioxidative enzymes and status of malondialdehyde (MDA), hydrogen peroxide (H2O2), proline and total phenols were studied in leaves of drought tolerant (PDG 3 and PDG 4) and susceptible (PBG 1, GPF 2, PBG 5, L 550 and BG1053) chickpea cultivars under irrigated and rainfed conditions at different development stages. In general, with the age of plant, the activities of superoxide dismutase (SOD) and catalase (CAT) increased but the activities of glutathione reductase (GR), ascorbate peroxidase (APX) and peroxidase (POX) decreased in leaves. With some exceptions, in general, higher status of APX and POX in leaves at vegetative stage I (30 days after sowing) and II (60 days after sowing); GR at vegetative stage II and pre-flowering stage and SOD and CAT at seed filling stages in tolerant cultivars under drought stress reflected stage specific upregulation of antioxidant defence system in them. The relatively lower activities of APX and POX in old leaves during seed filling stage make them more prone to enhanced oxidative injury than the young leaves. Lower content of hydrogen peroxide and malondialdehyde in leaves of tolerant cultivars during seed filling reflects the impact of antioxidant defence system operative at that time. The higher accumulation of proline and total phenol in leaves of tolerant cultivars might be playing important role in drought stress tolerance. These results indicated the importance of upregulation of different antioxidant enzymes at variable stages of leaf development.

RESPONSE OF MICROBES AND BIOREGULATORS ON YIELD PERFORMANCE OF CHICKPEA (CICER ARIETINUM L.) UNDER RAINFED CONDITION

ABSTRACT A field experiment was conducted to study the response of microbes and bioregulators on yield growth and productivity of chickpea (Cicer arietinum L.) under rainfed condition during 2010-11 and 2011-2012 on sandy loam soils with factorial randomized block design consisting of four levels of biofertilizers inoculation viz., no inoculation, phosphate solubilizing bacteria (PSB), vesicular arbuscular mycorrhizae (VAM) and PSB+VAM with two bio-regulators viz., homo-brassinolide @ 1 ppm and gibberelic acid @ 1000 ppm at pre-flowering and pod-filling stage. Result showed that the yield attributes like number of grains plant-1and test weight were highest in treatment receiving homo-brassinolide and dual inoculation of PSB+VAM. Grain yield was highest (2139 and 2211 kg ha-1) in treatment receiving PS+VAM application over no inoculation (957 and 1072 kg ha-1). The grain yield was highest (1705 and 1797 kg ha-1) in treatment receiving homo-brassnolide and lowest grain yield (1481 and 1569 kg ha-1) at gibberelic acid during 2010-11 and 2011-12, respectively.

EFFECTS OF Ca AND P NUTRIENT LEVELS ON THE GROWTH OF N-FERTILIZED AND RHIZOBIUM-NODULATED PHASEOLUS VULGARIS L. SUBJECTED TO TWO CONTRASTING TROPICAL SOLAR RADIATION REGIMES AND SPRAYED WITH PROPYL GALLATE

SUMMARYInteractions between two contrasting photosynthetic photon flux densities (PPFD) and increasing Ca and P concentrations were analysed in N-fertilised (+N) and Rhizobium-inoculated (+Rh) Phaseolus vulgaris plants grown for 30 days in glasshouses. Plants were grown in sand-filled Leonard jars with 0.9 L N-free for +Rh plants or plus 6 mM KNO3 for +N plants nutrient solution, pH 6.2 in the lower compartment, and were subjected to midday PPFD ≥ 1650 ≤ 1800 mmol m−2 s−1/37±2°C air temperature (HI/HT) or PPDF ≥ 900 ≤ 1200 μmol m−2 s−1/26±2°C air temperature (MI/MT). The nutrient solutions were supplied with 1, 2, 3 or 4 mM P in combination with 1 or 4 mM Ca. Results revealed a 100% mortality of the HI/HT+Rh plants at the juvenile stage of growth. Whereas, all HI/HT+N plants reached the preflowering stage but showed smaller shoot masses, lower chlorophyll concentrations, unusually high chlorophyll a/b ratios and higher shoot nitrate concentrations when compared to values in +N plants grown at MI/MT. Increasing concentrations of P and Ca, or the daily spray of leaves with 2 mM propyl gallate (Pg), did not counteract the negative effects of HI/HT on +Rh and +N plants. Maximum growth, nodulation, chlorophyll concentration and catabolism of ureides in leaves were exclusively observed in +Rh plants grown under MI/MT conditions and supplied with 2 mM P and 1 mM Ca. In contrast, the greater growth of +N plants, associated with higher chlorophyll and nitrate concentrations, took place at MI/MT conditions combined with 1 mM P and 4 mM Ca. Pg further enhanced the growth of MI/MT+Rh and MI/MT+N plants grown at P < 2 mM, at 1 or 4 mM Ca, respectively. At MI/MT, there was a positive relationship between leaf carotenoid concentration and growth of +Rh and +N plants.

Alteration in anti-oxidant defense system and protein expression in response to varied concentrations of EMS in Psoralea corylifolia

Germplasm of Psoralea corylifolia L., one of the most important endangered medicinal plants of Chinese and Indian Pharmacopeia were treated with ethyl methane sulphonate (0, 0.1, 0.25, 0.50, 0.75 and 1 %) and sampled for observations in the form of growth, non enzymatic systems and stress proteins at pre-and post-flowering stages of development. Higher concentrations of EMS showed significant (P < 0.001) inhibition in the germination percentage from 3.88 to 35.46 % at pre-flowering stage and from 4.90 to 35.97 % at post-flowering stage when compared to control. Other growth related parameters viz shoot growth and root growth also declined within increase in the dose as compared to control plants. Root growth was severely affected as compared to shoot growth. Roots showed a significant correlation with tolerance index as increasing concentration of EMS progressively inhibited the root growth. Plants developed from treated germplasm at higher doses exhibit higher activity of ascorbate peroxidase (APX), up to flowering and after that declined. Contrast to that, total soluble protein (TSP) content decreased in age and dose wise manner. The EMS dose applied and oxidative stress was correlated and derived from the increased antioxidant activities and decrease in total glutathione content from 122.75 % (GSH) and 103.29 % (GSSG) in plants raised from treated germplasm towards the post-flowering stage. Pronounced accumulation of psoralen from 10.74 to 93.24 % was observed following higher doses of EMS at post-flowering stage, where EMS induced oxidative stress-enhanced proline accumulation and lipid peroxidation. In addition, the prevalence of maximum antioxidant activity, psoralen accumulation was an efficient process in acclimatizing P. corylifolia to stress. 2-Dimensional gel electrophoresis (2D-GE) of the protein expression profile and MALDI TOF–MS revealed an expression of 20 different proteins which are associated with such functions as cellular detoxification, stress defense, psoralen production, photosynthesis, signal transduction, and cell cycle. The increase in the psoralen pool after EMS treatment proved to be a best protective antioxidant to counterbalance EMS-induced ROS detoxification and can be used as a biomarker and a scavenger in stress physiology.

Effect of short term irrigation with treated and untreated wastewater on growth and physio-biochemical parameters of wheat

Pot experiments were conducted to evaluate the possibility of use of treated and untreated wastewater for irrigation. Wastewater samples collected from electroplating, steel processing industrial units and common effluent treatment plant (CETP) were treated with Salvinia biomass. Wheat (Triticum aestivum), the staple food crop was chosen for the study. Seeds were sown in pots and irrigated with treated and untreated wastewater. Plants irrigated with tap water were designated as control. The growth of wheat was assessed at seedling and pre-flowering stages using various physiological and biochemical indices. The results obtained from the studies conducted for two consecutive seasons in net house indicated that levels of total chlorophyll, glucose, protein and photosynthetic efficiency was not significantly affected in plants irrigated with treated wastewater in comparison to those irrigated with tap water at both seedling and pre-flowering stages. In contrast, plants irrigated with untreated wastewater showed significant alteration in all the parameters at all the growth stages in comparison to control. The studies suggested that the treated wastewater can be used for irrigating crop plants as plant growth was not significantly affected.

Volatile Oil Composition and Antiplatelet Activity of Jordanian Achillea biebersteinii Collected at Different Growth Stages

Achillea biebersteinii Afan. (Asteraceae) is used as a traditional medicine for healing wounds and in the treatment of abdominal pain and stomach ache. Fresh and air dried flowering parts of A. biebersteinii at different growth stages were subjected to hydro-distillation and the different essential oils obtained were analyzed by GC-MS technique. Monoterpenoids dominated the different flowering stages of both, fresh and air dried flowering parts. The fresh pre-flowering stage was dominated by monoterpene hydrocarbons (56.62 %) with α-terpinene as the major component (51.67 %). Oxygenated monoterpenes were detected as the principal constituents during both, the fresh flowering and fresh post-flowering stages (55.61 %, 56.45 %, respectively). The major representatives of this class included ascaridol (38.84 %) and iso-ascaridol (25.39 %). Oxygenated monoterpenes dominated all flowering stages of the air-dried blooms and ascaridol was the main volatile compound in these oils (28.20 %, 27.03 % and 44.39 %, respectively). The oil of the dried mature flowering blooms of A. biebersteinii exhibited dose-dependent inhibition of the platelet aggregation caused by ADP and collagen.

Antioxidant activity of Ziziphora tenuoir methanolic extracts and comparison of the essential oil in two stages of growth

Flavonoids, anthocyanins, antioxidant capability, total phenolic, ascorbic acid contents, and essential oils compounds of Ziziphora tenuoir (Lamiaceae) for polar and non-polar subfraction in different stages of growth (pre-flowering and flowering) were evaluated in this work. Antioxidant activities of the samples were determined by three testing systems namely DPPH, β-carotene/linoleic acid, and reducing power assay. In the DPPH system, the highest radical scavenging activity was seen by the nonpolar subfraction of the methanol extract in the flowering stage (IC50 43.17 ± 3.68 μg·mL−1). Large differences in the amount of phenolic compounds, antioxidant activity, anthocyanins, and flavonoids of Z. tenuoir in two stages of growth were detected. The chemical composition of the hydrodistilled essential oil of the aerial parts of Z. tenuoir was analyzed by GC/MS and compared in the two stages of growth. The main constituents of the 28 identified compounds in the oil were found to be pulegone (67.34% vs 59.61%), β-humulene (3.24% vs 3.25%), and limonene (5.06% vs 2.57%) at the flowering and pre-flowering stages, respectively

Essential Oil Composition and Antibacterial Activity of Eryngium caeruleum Grown Wild in Iran

: An experiment was carried out to identify the essential oil composition and antibacterial activitiy on Eryngium caeruleum (Apiaceae). Aerial part of E. caeruleum was harvested at pre-flowering stage. Essential oil was obtained by hydro-distillation using Clevenger type apparatus during approximately 3 hours and analyzed using gas chromatography-mass spectrometry (GC-MS). Fifty six components were identified in E. caeruleum oil that represented 99.79 % of the oil. The main components of the oil were, cyclobuta[1,2,3,4]dicyclooctene, hexadecahydro (47.03 %), n-hexadecanoic acid (11.16 %), linoleic (5.41 %), limonene (4.23 %) and cis-α-bisabolene (2.14 %). Antibacterial activity of the essential oil was evaluated by micro broth dilution and disc diffusion methods. The oil showed high antibacterial activity against Streptomyces scabies, Xanthomonas axonopodis pv citri, Erwinia amylovora, Staphylococcus aureus, Bacillus subtilis and Klebsiella sp. But on the other bacteria tested is ineffective.

A Meta-Analysis on the Effects of 2,4-D and Dicamba Drift on Soybean and Cotton

Commercial introduction of cultivars of soybean and cotton genetically modified with resistance to the synthetic auxin herbicides dicamba and 2,4-D will allow these compounds to be used with greater flexibility but may expose susceptible soybean and cotton cultivars to nontarget herbicide drift. From past experience, it is well known that soybean and cotton are both highly sensitive to low-dose exposures of dicamba and 2,4-D. In this study, a meta-analysis approach was used to synthesize data from over seven decades of simulated drift experiments in which investigators treated soybean and cotton with low doses of dicamba and 2,4-D and measured the resulting yields. These data were used to produce global dose–response curves for each crop and herbicide, with crop yield plotted against herbicide dose. The meta-analysis showed that soybean is more susceptible to dicamba in the flowering stage and relatively tolerant to 2,4-D at all growth stages. Conversely, cotton is tolerant to dicamba but extremely sensitive to 2,4-D, especially in the vegetative and preflowering squaring stages. Both crops are highly variable in their responses to synthetic auxin herbicide exposure, with soil moisture and air temperature at the time of exposure identified as key factors. Visual injury symptoms, especially during vegetative stages, are not predictive of final yield loss. Global dose–response curves generated by this meta-analysis can inform guidelines for herbicide applications and provide producers and agricultural professionals with a benchmark of the mean and range of crop yield loss that can be expected from drift or other nontarget exposures to 2,4-D or dicamba.

Cloning and expression analysis of DtpsMADS1 gene from Doritaenopsis hybrid.

Plant MADS-box genes encode a family of highly conserved transcription factors which involved in many different developmental processes,including floral formation and flowering. To elucidate the molecular mechanisms of floral development in the monocotyledonous species Doritaenopsis hybrid,we isolated cDNA of a MADS-box gene from this plant by the method of 3' and 5' rapid amplification of cDNA ends using degenerate primers designed according to the MADS-box protein family conserved region from inflorescence rachis at flowering stage. The full length cDNA of this gene is 960 bp,with a 37 bp 5' UTR,an ORF of 753 bp and 185 bp 3' UTR encoding 245 putative amino acids. Sequence and phylogenetic analysis indicated a high degree of predicted protein sequence identity with those from other species. The gene belongs to the class of AP1 / FUL-like group of MADS-box genes and was termed as DtpsMADS1(accession No. JQ065097). Real-time quantitative PCR(qRT-PCR)results showed that DtpsMADS1 had obvious expression specificity in different organs;DtpsMADS1 had higher levels of expression in root and leaf at pre-flowering stage and post-flowering stage,meanwhile had lower levels of expression at seedling stage and full-blossom stage; The expression of DtpsMADS1 in inflorescence rachis showed the same tendency as root and leaf;However,only trace expression level was detected in flower organs. The results suggested that DtpsMADS1 could be involved in regulating the flowering process,not in floral morphogenesis.

Enhanced artemisinin accumulation and metabolic profiling of transgenic Artemisia annua L. plants over-expressing by rate-limiting enzymes from isoprenoid pathway

Artemisinin, a natural product isolated from aerial parts of Artemisia annua L. plant, is a potent antimalarial drug against drug-resistant malaria. In recent times, the demand (101–119 MT) for artemisinin is exponentially increasing with the increased incidence of drug-resistant malaria throughout the world, especially African and Asian continents. However, the commercial production of artemisinin-based combination therapies has limitation because of the presence of low concentration of artemisinin in plants. Therefore, transgenic lines of A. annua L. plants over-expressing both HMG-Co A reductase (hmgr) and amorpha-4, 11-diene synthase (ads) genes were developed to enhance the content of artemisinin. The selected transgenic lines (TR4, TR5, and TR7) were found to accumulate higher artemisinin (0.97–1.2%) as compared to the non-transgenic plants (0.63%). The secondary metabolite profiles of these lines were also investigated employing gas chromatography mass spectrometry, which revealed a clear difference in these metabolites in transgenic and non-transgenic lines of A. annua L. at different growth and developmental stages. The major metabolites reported in these lines at pre-flowering stage were related to essential oil and chlorophyll biosynthesis (71.33% in TR5 transgenic lines vs. 61.70% in non-transgenic line). Based on these results, we concluded that over-expression of both hmgr and ads genes in A. annua L. plants results not only increase in artemisinin content, but also enhances synthesis of other isoprenoid including essential oil. It is also evident from this study that the novel artemisinin-rich varieties of A. annua L. could be developed by suppressing essential oil biosynthesis, so that more carbon could preferentially be diverted from mevalonate pathway to artemisinin biosynthesis.

Salinity Tolerance of Super-Nodulating Soybean Genotype En-b0-1

Salinity stress causes various physiological dysfunctions in soybean (Glycine max (L.) Merr.). For example, reduced nitrogen (N) uptake due to salt-induced depression of nodule formation severely limits soybean growth and yield. Super-nodulating soybean genotypes were previously identified by their superior N2 fixation and photosynthesis. Here, we have tested our hypothesis that the super-nodulating En-b0-1 genotype is more salinity tolerant than a normal-nodulating genotype. The super-nodulating genotype and its parental normal-nodulating cultivar Enrei were grown in pots and subjected to saline conditions during the pre-flowering and reproductive growth stages. Under saline conditions imposed during pre-flowering, En-b0-1 formed heavier nodules, resulting in greater N uptake, higher photosynthetic activity, and greater biomass production compared with Enrei. Saline treatment increased the concentrations of sodium (Na) and chlorine (Cl) in all plant parts regardless of genotype; but in En-b0-1, the concentrations of these elements in shoots were significantly lower, while those in roots and nodules were higher than in Enrei. When the salinity treatment was imposed during the reproductive growth stages, En-b0-1 maintained higher N uptake, leading to better alleviation of salinity-induced yield reduction than in Enrei. The super-nodulating genotype En-b0-1 was more tolerant to salinity than its parental normal-nodulating cultivar, due to its superior nodulation and prevention of excessive accumulation of Na and Cl in shoots, which were retained in roots and nodules, thus supporting our hypothesis.

Effect of different insecticidal treatments on aphid (Lipaphis erysimikaltenbach) infestation, yield and yield contributing traits in Brassica rapa var sarson crop in Kullu valley of Himachal Pradesh, India

Different chemical treatments were applied at pre flowering stage succeeded by post bloom sprays on aphid, Lipaphis erysimi Kaltenbach infestation and yield and yield contributing traits of Brassica rapa (B.campestris) var sarson. The treatment consisting of the pre flowering soil treatment of carbofuran succeeded by post bloom spray of cypermethrin (T2) provided the best control of L. erysimi as significantly least dried siliquae/plant (3.03 and 2.09) were recorded during the two years observations. In case of unprotected crop, significantly higher number of dried siliqua/plant (16.70 and 16.73) was recorded during 2009-10 and 2010-11. The number of primary and secondary branches/plant, seeds/siliqua, thousand seed weight and seed yield were also significantly higher under this treatment.

Fermentation of Waste Fruits for Bioethanol Production

Pulses occupy a strategic position in intensive as well as subsistence agriculture, as they are excellent source of dietary protein for millions of people, nutritious feed for livestock and a mini nitrogen plant having profound ameliorative effect on the soil. Green gram is extensively grown in all types of soil under varying climatic conditions. Greengram is considered as the most whole some among pulses, free from heaviness and flatulence. The green pods are used as vegetable and haulms are used as fodder. On an average, the biomass has 1.5 per cent N on fresh weight basis, serving as a good source of animal feed. Flower and pod shedding is a common problem in greengram. There is also a possibility to overcome these constraints by foliar application of bioregulators at the pre-flowering stage, which is one of the latest trends in agriculture. These bioregulators includes humic acid (HA), naphthalene acetic acid (NAA), benzyl adenine (BA), salicylic acid (SA), brassinosteroid (BR) etc. These plant growth regulators (PGRs) in general, help to increase the number of flowers on the plant when applied at the time of flowering. The flower and pod drop may be reduced to some extent by spraying various growth regulators on foliage (Ramesh and Thirumuguran, 2001). The foliar application of PGRs and urea significantly increased seed yield per plant (Patil et al., 2005). The HA increased the yield of plants more especially, with insufficient nutrient supply than with optimum nutrient supply (Pagel, 1960). The NAA is one of the important synthetic, stable and also widely used form of auxins. Auxins had been very effective in promoting growth and development in pulse crops. Upadhayay (1994) reported that foliar spray of NAA at bud initiation and pod formation stage of chick pea increased plant height, number of branches, number of flower bud, number of flowers and yield. The main role of NAA rests with the efficient transport of sugars from the photosynthesizing parts of the plant (source) to the developing grains (sinks) and also facilitating nitrogen accumulation that probably resulted in higher total dry matter production (Kalita et al., 1989). Foliar spray of 25 ppm NAA Effect of humic acid with bio-regulators on the yield of greengram [Vigna radiata (L.) wikzek]

Effects of topography and crown-exposure on olive tree phenology

The importance of the olive tree phenology from agricultural and ecological point of view justifies the need to carry out phenological studies at local and regional scales. Furthermore, flowering phenology in the olive tree (Olea europaea L.) is an important indicator of climatic change in the Mediterranean region. In this paper, we study the effects of altitude and the exposure of crown-flowering branches on the flowering phenology of the olive tree. The study was carried out from 2009 to 2012 at eight sites of Cornicabra olive cultivar in central Spain (Toledo province, Castilla-La Mancha region), at altitudes between 440 and 875 m above sea level, since most olive groves in central Spain are to be found in this altitude range. Flowering phenology was also compared in two olive groves located at the same site and elevation; one in a flat area and the other on a north-facing hillside. Results revealed a significant correlation between altitude and flowering start-date: for each 100 m increase in altitude, flowering started 2.5 days later. Analysis of individual flowering branches of the same tree showed that preflowering and flowering started several days later on north-facing compared to south-facing branches. Olive trees growing on a north-facing hillside started the preflowering stage with some delay with respect to those growing in flat areas. Finally, taking onset of flowering as the variable, a hierarchical cluster analysis enabled olive-groves to be classified by flowering sequence across an altitudinal gradient.

Effect of physiological status on rooting of Masbedda (Gymnema sylvestre) cuttings

Vegetative propagation by means of cuttings is an important method for starting new plants identicalto the parent plants. Many plants can be propagated with good results by cutting, though the successdepends upon the propagator's circumstances, the time of year, and the plant to be propagated. Thepresent study was carried out to investigate the effect of physiological stage on rooting of Gymnemasylvestre stem cuttings.Healthy, double nodded cuttings were made from the mature plant stock established at the Faculty ofAgriculture, University of Ruhuna. The cuttings taken from pre-flowering (Tl), flowering (T2) andpost-flowering (T3) stages were stuck into preformed holes in poly bags filled with moistened rootingmedium which consisted of sand, top soil and compost (1 :1: 1 by volume). They were placed in a shadehouse and watered once a day. The Completely Randomized Design (CRD) was used with tenreplicates. Assessment was done 75 days after for rooting. The percentage survival was not significantly(p ~ 0.05) different between cuttings taken from the pre-flowering (92%) and post-flowering (87%)stages. No significant (p ~ 0.05) differences also in the percentage of callused and rooted cuttingswere recorded between T I and T3. However, number of roots and length of the longest root percutting were significantly (p ~ 0.05) higher in Tl than any other. Furthermore, T2 showed the lowestfigures for all the parameters assessed, indicating that the physiological status of the stock plant at thetime the cuttings are excised is of great importance for the rooting process.

Seasonal variation and low-cost agronomic practices effect growth and yield of moth bean (Vigna aconitifolia) in the extreme arid Thar desert

An experiment was laid out at Jaisalmer for three consecutive rainy seasons (2007 to 2009) to evaluate the effect of season and the efficacy of low-cost agronomic practices on the performance of moth bean (Vigna aconitifolia L.) in the extreme arid Indian Thar. Skip row planting (skipping every third row) significantly improved pods and seed weight per plant, and consequently seed yield, over normal planting. Total readily available water and moisture availability at critical growth stages of the crop significantly influenced plant attributes and thus biological and seed yield. Relative leaf water content (RWC) at sunrise in the pre- and post-flowering stages remained above the moisture stress level. However, at midday, plants experienced moderate stress in RWC during pre-flowering and severe stress during the post-flowering stages. Foliar application of 1% urea was found to be effective only when midday RWC is more than the critical threshold value of 84%. Therefore, foliar application of 1% urea at the pre-flowering stage significantly increased almost all plant attributes and yields, whereas second foliar application at post-flowering stage when midday RWC was <84% has no impact on plant attributes and yield.

Comparative reaction of popular high yielding spanish and virginia bunch groundnut varieties to Tobacco streak virus.

Reaction of five spanish (JL 24, TMV 2, Kadiri 6, Kadiri 9 and Anantha) and a virginia (Kadiri 7 Bold) groundnut cultivars was studied against Tobacco streak virus (TSV) by sap inoculation using different age group of plants [7-84days after sowing (DAS)]. Among different cultivars, incubation period varied from 4 to 28days and high incubation period recorded in Kadiri 7 Bold. The percent infection decreased with increase in the age of the plants in all the cultivars as it ranged up to 100% in both pre-flowering (7-21 DAS) and flowering stage (28-63 DAS) plants followed by 50-100% in maturity stage plants (70-84 DAS) except Kadiri 7 Bold. Similarly, 100% wilting was observed in pre flowering stage plants against no wilting in maturity stage plants. However, cultivars differed in per cent wilting of flowering stage plants by recording maximum wilting (100%) in JL24, Kadiri 6 and minimum (25.0%) in Kadiri 7 Bold. Both localized (necrotic spots, veinal necrosis) and systemic (petiole necrosis, necrotic spots on young leaves, top growing bud and stem necrosis, axillary shoot proliferation, stunting, peg necrosis, pod necrosis, wilting of plant) symptoms induced by TSV were similar among all cultivars without any new symptoms. Prolonged stage of axillary shoot proliferation was observed for the first time in all the cultivars. In maturity stage plants of Kadiri 7 Bold, Kadiri 9 and Anantha, systemic symptoms restricted to leaf and petiole necrosis only. Virus titer varied significantly with the age of plants and inoculum harvest at days post inoculation and least virus titer recorded by Kadiri 7 Bold at all stages of infection. Among different cultivars, Kadiri 7 Bold was least susceptible/tolerant to TSV by registering higher incubation period with less per cent infection, wilt and titer.

Morphophysiology, morphoanatomy, and grain yield under field conditions for two maize hybrids with contrasting response to drought stress

In the northern region of the state of Minas Gerais, lack of rainfall limits crop production in the field, which is possible only with irrigation. Agricultural and physiological practices have been intensively searched to overcome drought effects and consequently increase production. In this context, the objective of this study was to characterize morphophysiological and morphoanatomical changes and evaluate the attributes of grain yield under field conditions in two hybrids contrasting for drought tolerance. The experiment was carried out for 2 years (2010 and 2011) and the water deficit was imposed by stopping irrigation for 22 days at the pre-flowering stage. At the end of the stress treatment, leaf and root anatomy and morphophysiological characteristics (leaf water potential, chlorophyll content, percentage of dry leaves, leaf area, stomatal conductance, chlorophyll fluorescence, and anthesis-silking interval) were evaluated. For a better interpretation of tolerance of the hybrids in the evaluated characteristics, an index was used stress index. Hybrid DKB 390 (tolerant) surpassed hybrid BRS 1030 (sensitive) in grain yield. Furthermore, it presented lower percentage of dry leaves, higher flowering synchronization, higher stomatal conductance, and higher Fv/Fm relationship. In the root, DKB 390 showed higher amount of aerenchyma in the cortex, an increase of exodermis width, and numerous metaxylem with smaller diameter. In the leaf, it presented higher number of stomata and smaller distance between the vascular bundles in the leaf blade. The study concluded that significant morphophysiological and morphoanatomical changes, which are related to drought tolerance, occurred in DKB 390, leading to a higher yield in the field.