Sorghum Drought Tolerance is Associated with Deeper Root System and Decreased Transpiration Rate

Drought decreases grain yield of sorghum [Sorghum bicolor (L.) Moench], and understanding the mechanism(s) related to drought tolerance is critical for sustaining sorghum production. Variation in root and shoot traits associated with drought tolerance were analyzed to provide an integrated view of factors that underlie the drought tolerance of sorghum. The plants were grown in the root column up to the five-leaf stage, then exposed to either 0.9 fraction of transpirable soil water (FTSW) or 0.4 FTSW for five days. In another experiment, at the five-leaf stage, stress was imposed for 14 days. Various root and shoot traits associated with drought tolerance were recorded. The seminal root angle of IS13540 was lower (24.4) than IS23143 (42.6). Drought stress increased the maximum root length (40%) and total root length (58%) of IS13540 than its irrigated control. In contrast, the maximum root length and total root length were decreased in IS23143. Similarly, across the lines, drought stress decreased stomatal conductance (37%), transpiration rate (42%), photosynthetic rate (40%), photosystem II quantum yield (20%), photochemical quenching (44%), and total dry matter production (34%) than irrigated control. An increased transpiration rate was observed in IS23143 than IS13540 under irrigated and drought stress. In IS23143, the reduction in photosynthetic rate under drought may be a combination of stomatal and non-stomatal factors. However, in IS13540, the reduction is especially by the stomatal factors. It is evident that IS13540 is a drought-tolerant line, and tolerance is related to a deep prolific root system and reduced tran-spiration rate.

Trait variations and expression profiling of OsPHT1 gene family at the early growth-stages under phosphorus-limited conditions

To better understand the early response of genotypes to limited-phosphorus (P) conditions and the role of the phosphate transporter OsPHT1 gene family in the presence of PSTOL1, it is essential to characterize the level of tolerance in rice under limited-P conditions. In the present experiment, six rice genotypes were studied in three-way interactions [genotype (G) × phosphorus (P) × duration (D)] by comparing them at two instances (14 d and 28 d) under seven different concentrations of P (0.5‒10.0 ppm) in a hydroponic system. Trait differences and interactions of these traits were clearly distinguished among the various P rates. However, aboveground trait expression registered increased growth from 6.0 to 10.0 ppm of P. The major root-attributed traits in 0.5 ppm of P are significantly increased vis-à-vis 10 ppm of P. Analysis of variance displayed a significant difference between the genotypes for PSTOL1 and PHT1 expression. In low P, maximum root length with a shoot and root dry weight was observed in a new indigenous accession, IC459373, with higher expression of PSTOL1 than in Dular and IR64-Pup1 in 0.5 ppm of P at 14 d. Among the 13 PHT1 genes, OsPT1, OsPT2, OsPT6, and OsPT13 showed significant upregulation in IC459373, Dular, and IR64-Pup1. These results indicated that studying the expression levels of the PSTOL1 and PHT1 gene family at the early growth stages would be helpful in identifying superior donors to improve low-P tolerance and P-use efficiency in rice breeding programs.

IN-VIVO CONTROL OF FUSARIUM MONILIFORME CAUSING ROOT ROT OF JATROPHA THROUGH CHEMICAL AND AQUEOUS PLANT EXTRACTS

Jatropha (Jatropha curcas) is a plant of the Euphorbiaceae family that grows fast and able to be cultivated in tropical and subtropical regions. It is also known as Jamalghota and Jangli in different regions of the world and reported to be grown along with other crops such as wheat, sunflower, cluster bean, and pearl millet.Jatropha seeds were collected from the field of a project run by the Department of Agronomy, Sindh Agriculture University, Tando Jam. In the isolation process, seeds of jatropha were surface sterilized in a 5% bleach solution for 1-2 minutes to remove contamination.The experiment was carried in nursery bags to seethe effect of different doses of plant extracts on root rot of jatropha. The aqueous extract of different plant species was prepared by grinding freshly collected leaves of Neem, Ginger, Basil, Acasia, Garlic, Toothbrush plant, Eucalyptus, Giant milkweed, Mint, and Aloe vera separately. These extracts were then stained with a muslin cloth and a piqued solution was stored. Later it was used at the dose of 10ml, 20ml, and 30ml per bag containing disease-free (sterilized in soil sterilizer) soil. For comparison, two treatments (untreated, inoculated, and untreated, un-inoculated) bags were placed.The results of the experiment showed a significant growth of shoot length and weight in inoculated plants treated with the highest dose of Aliette, followed by Carbendazim, and Metalyxl+Mancozeb. Whereas minimum shoot length and weight was observed in control. Similarly, maximum root length and weight were recorded in plants treated with Aliette, followed by Carbendazim and Metalyxl+Mancozeb as compared to control.

An efficient protocol for mass multiplication of Centella asiatica (L.) Urban and determination of its phenolic content

The present study was focused on standardizing a protocol for callus induction as well as regeneration in Centella asiatica from leaf and stem as explants. Stem and leaf explants have been inoculated in B5 media supplemented with BAP (0.1-2.5 mg/l), kn (01-04 mg/l) and NAA (0.1-0.5 mg/l), 2, 4-D (0.2mg/l) for callus induction. The combination of BAP and NAA leads to the formation of green, brown, compact and friable calli while Kn and 2, 4-D induced brown calli. Highest shooting was obtained from BAP (1.5 mg/l) and NAA(0.5 mg/l).When the shoots were inoculated in half strength of B5 media fortified with 0.1 mg/l BAP and 0.5 mg/l NAA showed cent percent rooting with the highest number of roots per shoot (11.05 cm) and maximum root length (1.86 cm). Stem showed the best explants for callus induction as compared to leaf explants. A low concentration of plant growth regulators was unable to induced callus response in leaf and stem explants. Phenolic content analysis showed that calluses contain more amounts of phenol (0.81 mg/gmdw) as compared to both leaf (0.63 mg/gmdw) and stem (0.59 mg/gmdw) explants.

Effect of indigenous beneficial rhizobacterial isolates on growth of Litchi seedlings

A pot experiment was conducted to observe the effect of indigenous strains of rhizobacteria isolated from litchi orchards of East Champaran, Bihar (India) on the growth and survivability of litchi seedlings. Three efficient native rhizobacterial isolates belonging to genera Pseudomonas, Azotobacter and Ochrobactrum were used in seven different combinations and their effect on germination rate, shoot height, root length, number of leaves were observed and recorded in litchi seedlings. Pot 7 containing mixed combination of all the three isolates in equal proportion showed maximum root length (11.7 cm) and shoot length (12.5 cm), early germination as compared to control Pot P8 devoid of any isolates. Pot 4 (Pseudomonas + Azotobacter) and pot 5 (Pseudomonas + Ochrobactrum) also gave satisfactory result in all the parameters recorded. The results clearly state that, mixture of all the three rhizobacterial isolates as “Biomix” produced stimulatory growth results on litchi seedlings as compared to sole application and control. This “Biomix” could be used for formulating effective biofertilizers for litchi orchards in future.

Effect of Different Steeping and Malting Regimen on the Amylolytic Activities of Some Improved Nigerian Sorghum Grain Varieties

Three Nigerian improved sorghum varieties were evaluated to ascertain how different steeping and malting regimen affect their amylolytic enzyme development. Steeping incorporated air rest and continuous steep regime for 72 h. Samples were withdrawn every 12 h. Germination was then carried out for four days before kilning at 50°C for 24 h. Grain and malt parameters were examined. Results obtained showed variations in the response of sorghum root length to steep regimen and time. CSR-02 gave maximum root length (3.32 cm) after 72 h of air rested steeping. CSR-02, Samsorg 44 and Samsorg 14 had germinative energies of 92.00 ± 4.24, 94.00 ± 1.41 and 96.00 ± 1.41%; germinative capacities of 91.00 ± 1.41, 75.50 ± 2.12 and 88.00 ± 2.83; water sensitivities of 6.50 ± 2.12, 13.50 ± 1.44 and 1.00 ± 0.41 respectively. TKW results were 29.73 ± 0.32, 33.85 ± 1.54 and 33.51 ± 0.41 kg for CSR-02, Samsorg 44 and Samsorg 14 respectively. Variations in the response of the sorghum varieties to various conditions of steep regime and steep period were also observed. Steeping for 48 h seems to be the optimum time for the development of amylolytic activity in all the sorghum varieties at both steeping regimens. Samsorg 14 gave the highest total amylase activity (355.44 µg glucose equivalents), followed by Samsorg 44 (278.08 µg glucose equivalents). Samsorg 14 also showed the highest α-amylase development (276.93 µg glucose equivalents). Air rest was found to be show greater effect on β-amylase development in all the sorghum varieties.

The changes of morphological and physiological characteristics in hemiparasitic Monochasma savatieri before and after attachment to the host plant

Background Monochasma savatieri is an endangered hemiparasitic medicinal plant with a variety of antioxidant, antimicrobial and anti-inflammatory properties. Despite the urgent need to understand the parasitic biology of M. savatieri, parasite-host associations have long been neglected in studies of M. savatieri. Methods We conducted a pot cultivation experiment to analyze changes in the growth traits, physiological performance and anatomical structures of M. savatieri grown with the potential host Gardenia jasminoides E., before and after the establishment of the parasite-host association. Results Prior to the establishment of the parasite-host association, the presence of the host had no significant effect on the maximum root length, leaf indexes or total dry weight of M. savatieri seedlings, but had significant positive effect on seedling height, number of roots or number of haustoria. When it was continuously grown without a host, M. savatieri growth was rather slow. The establishment of the parasite-host association enhanced the growth of M. savatieri, and higher levels of photosynthetic pigments, increased antioxidant enzyme activity and lower malondialdehyde accumulation were observed in M. savatieri with an established parasite-host association. Furthermore, an analysis of the anatomical structures of M. savatieri showed that the establishment of the parasite-host association enabled better development of the seedling vegetative organs than that in seedlings without parasite-host associations. Conclusions Our study demonstrates the physiological and anatomical changes that occurred in M. savatieri after connection with a host and suggests that the enhanced growth and development of M. savatieri were highly dependent on the parasite-host association.

Sustainable and Ecofriendly Approach of Managing Soil Born Bacterium Ralstonia solanacearum (Smith) Using Dried Powder of Conyza canadensis

Bacterial wilt disease caused by Ralstonia solanacearum is a devastating plant disease that inflicts heavy losses to the large number of economic host plants it infects. The potential of dried powder of the Conyza canadensis to control bacterial wilt (BW) of tomato was explored in vitro and in planta. Three application times (16 days before transplanting (DBT), 8 DBT and 0 DBT), three plastic-mulch durations (10 days plastic mulching (DPM), 5DPM and 0DPM) and four doses viz. 0 g, 8 g, 16 g and 24 g of the plant powder were evaluated. SEM analysis was also conducted to observe the change in bacterial cell morphology. Ethanol extract of dried C. canadensis in different concentrations inhibited the in vitro growth of R. solanacearum by as much as 98% of that produced by ampicillin. As evident from the scanning electron micrograph, the highest concentration produced severe morphologic changes, such as rupture of the bacterial cell walls and cell contents leaked out. Results from application time and dose experiment demonstrated that the highest powder dose viz. 24 g kg−1 mixed with infested soil 16 DBT gave maximum root length (34.0 ± 2.5 cm), plant height (74.3 ± 4.7 cm), fresh biomass (58.3 ± 4.3 g), reduction in bacterial population (1.52 log10) and resulted in lowest AUDPC value (1156.6). In case of mulching duration and dose experiment the maximum root length (39.6 ± 3.2 cm), plant height (78.3 ± 5.8 cm), fresh biomass (65.6 ± 4.9 g) reduction in bacterial population (1.59 log10) and lowest AUDPC value (1251.6) was achieved through the application of highest powder dose viz. 24 g kg−1 and longest plastic mulching duration of 10 DPM. The better results of highest dose and longer application time can be explained on the basis of higher amounts of anti-microbial plant bio-active compounds in highest dose and the longer exposure time of the pathogen to these chemicals. The better results of longer mulching duration are due to faster and more complete decomposition (because of 10-days-long plastic-mulch-provided increased solar heat) of the dried powder which produced more amounts of volatile and non-volatile bactericidal compounds. Our results clearly suggest that the use of 24 g kg−1 dried plant powder of C. canadensis plastic-mulched for two weeks could be used as a reliable component of the integrated disease management program against BW.

Effects of one haustorium-inducing quinone DMBQ on growth and development of root hemiparasitic plant Monochasma savatieri

ABSTRACT: Monochasma savatieri Franch. ex Maxim is a perennial, parasitic herb used in traditional Chinese medicine and its wild resources have decreased sharply in recent years due to destructively harvesting and habitat destruction. Haustorium formation is a key event of parasites, but the concentrations of haustorium-inducing factors vary with species and cultivation conditions. In this study, we investigated the effects of the 2,6-dimethoxy-p-benzoquinone (DMBQ) concentration and cultivation density on the growth traits, haustorium formation and biomass of M. savatieri in the absence of a host plant. The results showed that both the DMBQ concentration and cultivation density regulated growth traits, haustorium formation and biomass in M. savatieri. The number of haustoria was significantly positively correlated with seedling height, maximum root length, the number of root tips and total dry weight. Membership function analysis revealed an overall greater increase in growth traits, haustorium formation and biomass when M. savatieri was treated with 10 μmol·L-1DMBQ and grew solitarily. These results offer an understanding of growth in M. savatieri influenced by the DMBQ concentration and cultivation density, which may aid in the establishment of a comprehensive cultivation system for M. savatieri or similar plants.

Megalobrama amblycephala grazes preferentially on Hydrilla verticillata but makes more efficient use of Vallisneria denseserrulata: implications for biological control of submerged macrophytes

Growth of the meadow-forming macrophyte Vallisneria denseserrulata is often negatively impacted as result of shading by the canopy-forming Hydrilla verticillata. Grazing by the herbivorous cyprinid Megalobrama amblycephala is thought to control H. verticillata. We hypothesized that M. amblycephala would prefer H. verticillata over V. denseserrulata, and that where the latter is grazed, its growth will not be wholly compromised, due in part to the efficiency with which it is metabolized by the grazer. In a pond experiment, macrophytes were planted with monocultures of H. verticillata and V. denseserrulata, and in mixed cultures of the two species, with and without grazing by M. amblycephala. The results showed that in the absence of fish, the growth rate of V. denseserrulata was significantly reduced in the presence of H. verticillata. In the mixture, M. amblycephala had a significant negative effect on the growth of H. verticillata but not on V. denseserrulata. Grazing was associated with reductions in plant height, plant fresh weight and leaf fresh weight but the leaf number, maximum root length, maximum blade width, root weight and stem weight in V. denseserrulata increased. The food utilization ratio of M. amblycephala was significantly higher when grazing solely on V. denseserrulata than when grazing on H. verticillata or the mixture. Our results imply that V. denseserrulata is protected from overgrazing by the ability of M. amblycephala to make more effective metabolic use of ingested material than for H. verticillata. Furthermore, M. amblycephala is beneficial to V. denseserrulata in reducing competition from H. verticillata.