Photosynthetic acclamatory response of Panicum antidotale Retz. populations to root zone desiccation stress

Growth of plants is severely reduced due to water stress by affecting photosynthesis including photosystem II (PSII) activity and electron transport. This study emphasised on comparative and priority targeted changes in PSII activity due to progressive drought in seven populations of Panicum antidotale (P. antidotale) collected from Cholistan Desert and non-Cholistan regions. Tillers of equal growth of seven populations of P. antidotale grown in plastic pots filled with soil were subjected progressive drought by withholding water irrigation for three weeks. Progressive drought reduced the soil moisture content, leaf relative water content, photosynthetic pigments and fresh and dry biomass of shoots in all seven populations. Populations from Dingarh Fort, Dingarh Grassland and Haiderwali had higher growth than those of other populations. Cholistani populations especially in Dingarh Grassland and Haiderwali had greater ability of osmotic adjustment as reflected by osmotic potential and greater accumulation of total soluble proteins. Maximum H2O2 under water stress was observed in populations from Muzaffargarh and Khanewal but these were intermediate in MDA content. Under water stress, populations from Muzaffargarh and Dingarh Fort had greater K+ accumulation in their leaves. During progressive drought, non-Cholistani populations showed complete leaf rolling after 23 days of drought, and these populations could not withstand with more water stress condition while Cholistani populations tolerated more water stress condition for 31 days. Moreover, progressive drought caused PSII damages after 19 days and it became severe after 23 days in non-Cholistani populations of P. antidotale than in Cholistani populations.

Osmolyte-induced water deficit stress mitigation during panicle initiation stage in transplanted rice (Oryza sativa L.)

A field experiment was conducted to observe the osmolyte-induced water deficit stress mitigation during the panicle initiation stage in transplanted rice (Oryza sativa L. cv. BRRI dhan72). At the panicle initiation stage, plants were simulated with four levels of water regimes viz., well-irrigated (D0), water deficit for 5 d (D1), 10 d (D2) and 15 d (D3). Plants were treated with or without 10 mM of proline (Pro) and trehalose (Tre) as foliar spray started at mid-vegetative stage and continued till the end of stress period. Results revealed that water deficit stress drastically reduced most of the plant morpho-physiological attributes while other yield contributing characters were also affected due to prolonged water deficit stress. However, exogenous application of osmolytes like Pro and Tre significantly increased all those morphological, physiological and yield contributing parameters. Foliar addition of osmolytes concomitantly decreased the number of non-effective tillers hill-1 and the number of unfilled grain panicle-1 under water stress condition. Although both the osmolytes performed well under multiple duration of drought stress, the application of 10 mM Pro markedly improved all growth and yield contributing parameters under D1 water deficit stress compared to other stress durations. Hence, it may be concluded that the use of osmolytes would be a prospective remedy against moderate water deficit stress in transplanted rice production.

Drought Stress Amelioration in Maize (Zea mays L.) by Inoculation of Bacillus spp. Strains under Sterile Soil Conditions

The aim of the present study was to promote plant growth characteristics including mineral uptake and various phytohormone production by indigenously isolated Bacillus spp. strains. Plants subjected to normal and water stress conditions were collected after 21 days to measure physiological parameters, photosynthetic pigment estimation, biochemical attributes, lipid peroxidation and antioxidant enzyme response modulation. Our results correlated with drought stress amelioration with the inoculation of Bacillus spp. strains BEB1, BEB2, BEB3 and BEB4 under sterile soil condition. Inoculated plants of both maize cultivars showed increases in fresh (56.12%) and dry (103.5%) biomass, plant length (42.48%), photosynthetic pigments (32.76%), and biochemical attributes with enhanced nutrient uptake. The overall maize antioxidant response to bacterial inoculation lowered the malonaldehyde level (59.14%), generation of hydrogen peroxide (45.75%) and accumulation of flavonoid contents in both control and water stress condition. Activity of antioxidant enzymes, catalase (62.96%), peroxidase (23.46%), ascorbate peroxidase (24.44%), and superoxide dismutase (55.69%) were also decreased with the application of bacterial treatment. Stress amelioration is dependent on a specific plant–strain interaction evident in the differences in the evaluated biochemical attributes, lipid peroxidation and antioxidant responses. Such bacteria could be used for enhancing the crop productivity and plant protection under biotic and abiotic stresses for sustainable agriculture.

Effects of phosphorus and iron on biomass production and nutrients partitioning in soybean cultivars under water stress condition

A pot experiment was conducted to investigate the effects of P and Fe application on the biomass production and nutrients partitioning of two soybeans (Glycine max. L. Merr) cultivars grown in carbonated chernoziom (low in Fe and P) under water stress conditions. P and Fe were applied at two levels (0 and 100 mg P kg-1 soil; 0 and 5 mg Fe kg-1 soil). Control plants were grown at 70% water holding capacity (WHC) while their counterparts were subjected to 35% WHC water stress at initial flowering stage for two weeks. Considerable variability was observed in leaves, roots dry mass accumulation and nodulation among the soybean cultivars (Zodiac, Licurici) at both P and Fe levels in relation to water regimes. The results showed that drought significantly reduced biomass production irrespective of nutrient supply and its adverse effect was more pronounced at low nutrient supply. Leaf development and nodules growth were the most sensitive to water deficit and insufficient nutrient supply. Adequate P and Fe supply increased dry matter production and nutrient concentrations for soybean cultivars. Phosphorus concentration in plant parts was significantly higher at nil Fe compared with Fe application. Phosphorus application decreased Fe allocation to the leaves. The experimental results demonstrated that there was a positive effect of P and Fe adequate nutrition on P use efficiency. Hence, the sufficient phosphorus and iron supply maintained growth at high level, improved P and Fe status and partially alleviated drought effect on soybean plants.

Effects of Water Stress on Vegetative and Reproductive Traits of Three Commercial Cotton Varieties in Field Conditions in Central Iran

Backgroundwater scarcity is one of the most important factors that restricts crop production specially, cotton which must planted in areas without cold temperature limitation. Most of such area in Iran encounters drought events, hot temperatures and high atmospheric evaporative demand. So, understanding of stress severity and cultivar responses will help to better management of crop in stress conditions. Our previous study showed that cultivar responses in view of some physiological and morphological aspects were highly different in water stress condition. In this study we focused on yield formatting traits.Results Three cotton commercial varieties; Khorshid, Khordad and Varamin studied in sever, mild and without water stress. In normal condition zero type cultivar, the khorshid, produced the highest seed cotton yield. Varamin cultivar had more and longer sympodial branches which could raise it’s yield. Also, Varamin cultivar’s seed cotton yield was higher than the others (3617 kg -1 ha compared with 2477 and 3060 for khordad and khorshid, respectively). Khorshid was superior to the others at sever water stress.ConclusionSeed cotton yield showed high correlation whit boll number and boll weight and vegetative aspects such as plant height, node number and sympodial branches number. Management for developing more sympodial branches results in higher bud and flower and will increase the yield. Totally, we recommend Khorshid and Varamin cultivars for normal condition and Khorshid for sever stress conditions.

Deciphering the Mechanisms of Microbe Mediated Drought Stress Alleviation in Wheat

Drought stress adversely influences the crop plants. Herein, present research was designed to elucidate the role of plant growth promoting microbes for amelioration of water stress in wheat. A pot experiment was conducted for screening the microorganisms on the basis of plant growth, chlorophyll and proline content under water stress. Bacillus sp. BT3 and Klebsiella sp. HA9 were found more promising strains that positively influenced the plant growth, chlorophyll and proline status of seedlings under water stress condition. Further, Bacillus sp. BT-3 and Klebsiella sp. HA9 along with check strain (BioNPK) were used for elucidating their detailed effect on morphological, biochemical, physiological and molecular traits to mitigate drought stress in wheat. Microbial inoculation significantly enhanced plant growth, biomass, relative water content, chlorophyll content and root morphological parameters over the uninoculated water stressed (30% FC) control. Likewise, sugar content, protein content and antioxidant enzymes were also significantly enhanced due to microbial inoculation under water stress (30% FC). Microbial inoculation significantly decreased proline, glycine betaine, lipid peroxidation, peroxide and superoxide radicals in wheat over the uninoculated water stressed (30%FC) control. Quantitative real-time (qRT)- PCR analysis revealed that Bacillus sp. BT-3, Klebsiella sp. HA9 and BioNPK inoculation significantly upregulated stress responsive genes (DHN, DREB, L15 and TaABA-8OH) over the uninoculated water stressed (30% F.C.) control. The study reports the potential of Bacillus sp. BT3 and Klebsiella sp. HA9 along with BioNPK in water stress alleviation in wheat which could be recommended as effective biofertilizers.

Influence of Different Irrigation Strategies on Yield and Water Use of Dry Bean (Phaseolus vulgaris L.) in Semi-Arid Zone

Increasing population and challenges among the sectors due to the climate change and incorrect water policy has increased the pressure on water resources. This situation being as a global crisis particularly in respect to the food security has accelerated productive utilization of water supplies. The aim of the current study with 2-year experiments was to identify the effect of different irrigation interval and irrigation regimes on the yield and yield components of dry bean having greater than 50% of total world legumes production. In that experiment, two different irrigation interval, 7 and 14-day, and three different irrigation levels, (I100, I75 and I50, were studied. In results, the maximum yield was obtained from 7-day irrigation interval, and 28% yield reduction was detected at 14-day irrigation interval. In examine the irrigation levels, the highest yield was found at full irrigation (I100), and increasing water stress caused significant yield reductions e.g. 21% and 49% for I75 and I50, respectively. The evapotranspiration and total applied water as an average of 2013-2014 were calculated as 533 mm, and 450 mm, respectively. In assessment of the both the combine year results, the ky value was determined as 1.59, and this finding shows that dry bean crop is sensitive to the water stress condition.

Evaluation of Garden Pea (Pisum sativum var. hortense L.) Genotypes Under Irrigated and Rainfed Condition under Foothills of Terai Agro-ecological Region of West Bengal

The experiment was carried out to study the performance of garden pea genotypes for growth, yield and quality during rabi season (November to april) of 2017–18 and 2018–19 with the help of split plot design through three number of replications. The results of the study revealed that, early flowering, flowering at early node and days to first harvest was earlier by 2.32, 2.90 and 0.89 days, respectively in rainfed conditions. Yield parameters like individual plant yield, number of pods plant-1, individual pod weight and total fresh yield were significantly reduced by water stress condition. Number of nodules plant-1 (7.93) and nodule dry weight (97.01 g) decreased in rainfed conditions, whereas root length (22.33 cm) was higher in rainfed condition. Considering yield, benefit cost ratio and moisture stress tolerance of garden pea genotypes, TSS content of fresh seeds was higher in rainfed conditions. Quality parameters such as protein content and shelling percentage were higher in irrigated conditions. Ascorbic acid content remained unchanged under both growing conditions. The varieties such as Arka Apoorva, Arka Priya, Goldie and GS-10 may be selected for cultivation under both irrigated and rainfed conditions. On the basis of per se performance and drought tolerant indices Arka Apoorva, Arka Priya and Jindal-10 may be selected as suitable for growing under moisture stress condition in terai agro-ecological condition of West Bengal.