Leaf Tip Burn Research Articles

Similar and divergent responses to salinity stress of jamun (Syzygium cumini L. Skeels) genotypes.

Genetic variation for salt tolerance remains elusive in jamun (Syzygium cumini). Effects of gradually increased salinity (2.0-12.0 dS/m) were examined in 20 monoembryonic and 28 polyembryonic genotypes of jamun. Six genotypes were additionally assessed for understanding salt-induced changes in gas exchange attributes and antioxidant enzymes. Salt-induced reductions in leaf, stem, root and plant dry mass (PDM) were relatively greater in mono- than in poly-embryonic types. Reductions in PDM relative to control implied more adverse impacts of salinity on genotypes CSJ-28, CSJ-31, CSJ-43 and CSJ-47 (mono) and CSJ-1, CSJ-24, CSJ-26 and CSJ-27 (poly). Comparably, some mono- (CSJ-5, CSJ-18) and poly-embryonic (CSJ-7, CSJ-8, CSJ-14, CSJ-19) genotypes exhibited least reductions in PDM following salt treatment. Most polyembryonic genotypes showed lower reductions in root than in shoot mass, indicating that they may be more adept at absorbing water and nutrients when exposed to salt. The majority of genotypes did not exhibit leaf tip burn and marginal scorch despite significant increases in Na+ and Cl-, suggesting that tissue tolerance existed for storing excess Na+ and Cl- in vacuoles. Jamun genotypes were likely more efficient in Cl- exclusion because leaf, stem and root Cl- levels were consistently lower than those of Na+ under salt treatment. Leaf K+ was particularly little affected in genotypes with high leaf Na+. Lack of discernible differences in leaf, stem and root Ca2+ and Mg2+ contents between control and salt treatments was likely due to their preferential uptake. Correlation analysis suggested that Na+ probably had a greater inhibitory effect on biomass in both mono- and poly-embryonic types. Discriminant analysis revealed that while stem and root Cl- probably accounted for shared responses, root Na+, leaf K+ and leaf Cl- explained divergent responses to salt stress of mono- and poly-embryonic types. Genotypes CSJ-18 and CSJ-19 seemed efficient in fending off oxidative damage caused by salt because of their stronger antioxidant defences. Polyembryonic genotypes CSJ-7, CSJ-8, CSJ-14 and CSJ-19, which showed least reductions in biomass even after prolonged exposure to salinity stress, may be used as salt-tolerant rootstocks. The biochemical and molecular underpinnings of tissue tolerance to excess Na+ and Cl- as well as preferential uptake of K+, Ca2+, and Mg2+ need to be elucidated.

The Influence of Consortia of Beneficial Microorganisms on the Growth and Yield of Aquaponically Grown Romaine Lettuce

This study evaluated the effects of fish farm wastewater from the production of hybrid sturgeon (Acipenser gueldenstaedtii Brandt × Acipenser baeri Brandt) on the growth and quality parameters of romaine lettuce (Lactuca sativa var. longifolium cv. “Elizium”). The tested combinations were fish farm wastewater, fish farm wastewater enriched with one of the three microbiological consortia, and fish farm wastewater supplemented with minerals. The best growth parameters of romaine lettuce plants were obtained in the combination of wastewater from fish farming supplemented with mineral nutrients. The application of fish farm wastewater and beneficial microbiological consortia positively influenced the fresh weight of lettuce leaves and the number of leaves per plant. However, plants fed with wastewater supplemented with minerals were characterized by the strongest symptoms of leaf tip-burn and the lowest commercial value. By comparison, plants fed only with fish farm wastewater or wastewater with microorganisms were characterized by a high, similar commercial value. After the application of increased doses of minerals, there was evidence of greater activity of microorganisms involved in nutrient cycling in aquaponic lettuce cultivation. The application of the microbiological consortia and minerals significantly increased the numbers and activity of the bacteria in the culture liquids 7, 14, and 21 days after inoculation.

Optimization of an Indoor DWC Hydroponic Lettuce Production System to Generate a Low N and P Content Wastewater

Hydroponic production raises economic and environmental issues related to the treatment, recovery or disposal of hydroponic wastewater, which can be rich in eutrophication-related nutrients, nitrogen (N) and phosphorus (P). Little focus has been put on the influence of the growth conditions on the N and P content in hydroponic wastewater, which is of uttermost importance when it is intended to reuse the wastewater for irrigation or other purposes with reduced impact on the environment. This study aimed to optimize an indoor non-recirculating deep-water culture (DWC) hydroponic system for lettuce (Lactuca sativa L. var. crispa) production, in terms of daily light integral (DLI) and volume of nutrient solution (NS) per plant, to maximize both the biomass production and the N and P removal, allowing for the wastewater to meet the criteria established for reusing in irrigation and minimizing the eutrophication impacts. A small-scale DWC hydroponic system with a fluorescent light fixture was built to study lettuce growth indoors for 35 days after transplanting (DAT). A first experiment was conducted under 14, 20 or 23 mol m−2 d−1 DLI and with 1.5 or 2 L of NS per plant. A pronounced inner leaf tip burn was observed, regardless of the volume of NS solution used, related to the unventilated conditions under high radiation. Total biomass was similar in all treatments and N and P removal was higher than 95% and 94%, respectively, at 35 DAT. Lettuces grown in 2 L of NS per plant exhibited higher average biomass. A second experiment was performed under 8, 10 or 12 mol m−2 d−1 DLI and with 2 or 3 L of NS per plant, making it possible to achieve healthy biomass at 35 DAT with higher water and light-use efficiency when compared to the first experiment. A DLI of 10 or 12 mol m−2 d−1 with 2 L of NS per plant and a DLI of 12 mol m−2 d−1 with 3 L of NS per plant made it possible to achieve both the best total biomass production and the highest N and P removal from water. Under those conditions, hydroponic wastewater complied with N and P criteria for reuse in irrigation, showing potential to be used as an alternative resource for agriculture and to minimize negative impacts on the environment.

Effect of Soil Moisture and Calcium Deficiency on Incidence of New Branch Necrosis and Tip-Burn in Jujube (Zizyphus jujuba Mill.)

Jujube (Ziziphus jujuba Mill.) is the most important native species of Rhamnaceae, a large cosmopolitan family, and is one of the oldest cultivated fruit trees in the world. In recent years, consumption of fresh fruit and big fruit jujube has increased. The purpose of this study was to investigate the causes and its alleviation techniques of new branch necrosis and tip-burn, which occur in jujube during the new branch growth period. As a result of analyzing the inorganic component content of leaves, the calcium content was markedly 1.48% of abnormal samples compared to 1.90% of normal samples appeared low. Also, the calcium content in a necrotic new branch was also 0.14%, which was very low compared to 0.76% in the normal sample. In addition, the incidence rate of tip-burn at -30 kPa by soil at starting point of irrigation was 16.53%, higher than 7.22% at -10 kPa. The incidence of tip-burn by calcium foliar application was 0.6%, which was very low compared to control of 4.3%. Therefore, this study suggests that the symptoms of necrosis of new branch and tip-burn that occur during the new branch growth period of Jujube are related to the calcium content in the plant and lack of soil moisture and that calcium foliar application is effective in alleviating the occurrence of these abnormal symptoms.Alleviation effect of leaf tip-burn by Ca foliar application.

Silicon Supplementation Alleviates Adverse Effects of Ammonium on Ssamchoo Grown in Home Cultivation System.

Ssamchoo is recently attracting attention as a household hydroponic vegetable in Korea. It has a refreshing texture and a rich content of vitamins and fiber. Ssamchoo with a wide leaf area is suitable for traditional ssam or vegetable wraps, as well as a vegetable for salads; thus, it can be used in a variety of dishes. However, Ssamchoo plants responds sensitively to the nutrient solution, and it is often difficult to secure sufficient leaf area and robust growth using a commercial nutrient solution for leafy vegetables. This study consisted of three experiments conducted to develop the nutrient solution for Ssamchoo grown in a newly developed home hydroponic cultivation system using light-emitting diodes as the sole source of light. In the first experiment, growth and development of Ssamchoo in a representative commercial nutrient solution, Peters Professional (20-20-20, The Scotts Co., Marysville, OH, USA), was compared with laboratory-prepared nutrient solutions, GNU1 and GNU2. As a result, the Ssamchoo grown in Peters Professional had a high NH4+ content in the tissue, leaf yellowing, darkened root color, and suppressed root hair development. In addition, adverse effects of ammonium such as low fresh weight and shorter shoot length were observed. In the second experiment, Peters Professional was excluded, and the ratio of NO3- to NH4+ in the GNU1 and GNU2 nutrient solutions was set to four levels each (100:0, 83.3:16.7, 66.7:33.3, and 50:50). As a result, the fresh weights of 83.3:16.7 and 66.7:33.3 were the greatest, and the leaf color was a healthy green. However, at 100:0 and 50:50 NO3-/NH4+ ratios, the fresh weight was low, and leaf yellowing, tip burn, and leaf burn appeared. The nutrient solution with a 83.3:16.7 NO3-- to-NH4+ ratio, which gave the greatest fresh weight in the second experiment, was chosen as the control, while the solution with a 50:50 NO3-/NH4+ ratio with a lower nitrate content among the two unfavorable treatments was selected as a treatment group for the next experiment. In the third experiment, NH4+ was partially replaced with urea to make four different ratios of NO3- to NH4+ to urea (83:17:0, 50:50:0, 50:25:25, and 50:0:50) in combination with two levels of Si (0 and 10.7 mmol·L-1 Si). The greatest fresh weight was obtained in the treatment in which the NO3-/NH4+/urea ratio was 50:25:25. In particular, when Si was added to the solution, there was no decrease in the number of leaves, and plants with the greatest fresh weight, chlorophyll content, and leaf area were obtained. The number of leaves and leaf area are important indicators of high productivity since the Ssamchoo is used in ssam dishes. It can be concluded that a solution with a NO3-/NH4+/urea ratio of 50:25:25 and supplemented with 10.7 mmol·L-1 Si is the most suitable nutrient solution for growing Ssamchoo in the home hydroponic system developed.

Physiological and Molecular Approaches for Developing Thermotolerance in Vegetable Crops: A Growth, Yield and Sustenance Perspective

Vegetables are a distinct collection of plant-based foods that vary in nutritional diversity and form an important part of the healthy diet of the human being. Besides providing basic nutrition, they have great potential for boosting human health. The balanced consumption of vegetables is highly recommended for supplementing the human body with better nutrition density, dietary fiber, minerals, vitamins, and bioactive compounds. However, the production and quality of fresh vegetables are influenced directly or indirectly by exposure to high temperatures or heat stress (HS). A decline in quality traits and harvestable yield are the most common effects of HS among vegetable crops. Heat-induced morphological damage, such as poor vegetative growth, leaf tip burning, and rib discoloration in leafy vegetables and sunburn, decreased fruit size, fruit/pod abortion, and unfilled fruit/pods in beans, are common, often rendering vegetable cultivation unprofitable. Further studies to trace down the possible physiological and biochemical effects associated with crop failure reveal that the key factors include membrane damage, photosynthetic inhibition, oxidative stress, and damage to reproductive tissues, which may be the key factors governing heat-induced crop failure. The reproductive stage of plants has extensively been studied for HS-induced abnormalities. Plant reproduction is more sensitive to HS than the vegetative stages, and affects various reproductive processes like pollen germination, pollen load, pollen tube growth, stigma receptivity, ovule fertility and, seed filling, resulting in poorer yields. Hence, sound and robust adaptation and mitigation strategies are needed to overcome the adverse impacts of HS at the morphological, physiological, and biochemical levels to ensure the productivity and quality of vegetable crops. Physiological traits such as the stay-green trait, canopy temperature depression, cell membrane thermostability, chlorophyll fluorescence, relative water content, increased reproductive fertility, fruit numbers, and fruit size are important for developing better yielding heat-tolerant varieties/cultivars. Moreover, various molecular approaches such as omics, molecular breeding, and transgenics, have been proved to be useful in enhancing/incorporating tolerance and can be potential tools for developing heat-tolerant varieties/cultivars. Further, these approaches will provide insights into the physiological and molecular mechanisms that govern thermotolerance and pave the way for engineering “designer” vegetable crops for better health and nutritional security. Besides these approaches, agronomic methods are also important for adaptation, escape and mitigation of HS protect and improve yields.

Reduction of leaf tip burns of Ornithogalum dubium by controlling the temperature during bulb storage and greenhouse forcing to produce quality plants

Production of quality potted Ornithogalum dubium Houtt. plants were investigated under multiple conditions: pre-planting treatment at 10, 16, and 22°C for 40 days from Sept. 21 (stage A; ST-A) during bulb storage and then bulbs were potted. After potting, post-planting treatment at 15/12, 18/15, and 21/18°C (day/night) during stage B for 35 days from Nov. 2 (stage B; ST-B), and at 15/12 and 21/18°C during stage C for 30 days from Dec. 7 (stage C; ST-C) during greenhouse forcing was applied. Leaf tissue analyses for macro- and micro-nutrients were performed to investigate the cause of leaf tip burn symptom (LTB). Three criteria for quality of the plants at flowering were established: (1) LTB occurs on less than 1.5 leaves per plant. (2) the number of days to flower is less than 115 days, the length of the third leaf counted from the crown (the junction of the shoot and roots) is shorter than 11.5 cm, and the width is narrower than 2.5 cm; the scape length is shorter than 15 cm, and there are more than 45 flowers. (3) the leaf spread and morphology (leaf spread) and the pattern of the scape curvature (scape growth) have a score of less than 1.5. The following conditions are optimal to produce quality plants based on these three criteria: (1) Pre-planting bulbs treatment was applied at 10 or 16°C during ST-A, and forcing was performed at 15/12°C during ST-B and 21/18°C during ST-C. These conditions accelerated flowering, produced straight scape growth and upward (erect) growing leaves, and yielded acceptable leaf length and width. (2) The incidence of LTB was minimal at 10°C or possibly 16°C during ST-A, and at 15/12°C in ST-B and at 21/18°C in ST-C during greenhouse forcing. Leaf tip burn symptom was observed in both young and old leaves and was caused by a high boron (B) concentration (218-230 ppm) and possibly a high zinc (Zn) concentration (155-159 ppm) in O. dubium. A low calcium (Ca) concentration was not the cause of LTB. Although LTB cannot be avoided, it can be minimized by temperature manipulation during pre- and post-planting phase to produce high quality potted plants.

Evaluation of Productivity and Quality of Romaine and Iceberg Lettuce (Lactuca sativa L.) Under Siwa Conditions تقیییم الانتاجیة والجودة لخس الرومین والایسبرج تحت ظروف سیوة

The trailswere conducted during two consecutive seasons (2017 - 2018 and 2018-2019) in open field at Siwa Experimental Farm Station, at latitude 29o 12’ N, longitude 25o 29’E and 18 meters below sea level, Marsa Matrouh Governorate, Egypt, to evaluate the effect of three plant density and spraying of two calcium concentrates on growth, yield and quality of two lettuce types grown at winter seasons. Dark green and Mason cultivars represented of both romaine and iceberg lettuce type were transplanted at plant spacing of 25x20, 25x25 and 25x30 cm to give a plant population about 20, 16 and 13 plants per square meter and treated with 300 or 200 ppm of calcium chelate, as well as control treatment. The results indicated that, in spite of decreasing number of marketable heads per plot, low plant density improved average head weight, head diameter, leaf tip-burn, head compactness, as well as enhancement of nutritional value vs, dry matter, Ascorbic acid, potassium and calcium content. Both calcium treatments have a positive effect on lettuce yield and almost quality characters when compared with control treatment, except, average head weight, head diameter, head compactness, leaf tip-burn and dry matter content, dark green as romaine lettuce type produced highest number of marketable heads per planting area, early yield, highest head of water, ascorbic acid, potassium and calcium content. Egyptian market transplanting showed that romaine lettuce type with high density and calcium foliar spray is recommended.

Bio-Efficacy of Milastin-K (Bacillus subtilis KTSB 1015 1.5% A.S.) as a Potential Bio-Control Agent for Management of Bacterial Blight (Xanthomonas axonopodis) and Anthracnose (Colletotrichum gloeosporioides) Diseases in Pomegranate

Field bio-efficacy study was conducted during 2018-19 for evaluation of Milastin-K (Bacillus subtilis KTSB 1015 1.5% A.S.) for control of bacterial blight (Xanthomonas axonopodis pv. punicae) and anthracnose (Colletotrichum gloeosporioides) on leaves, fruit and yield of pomegranate. The trial was conducted during Late Hasta Bahar at Vasantrao Naik Marathwada Krishi Vidyapeeth, Parbhani. The trial was conducted in RBD with three replications and twelve treatments. Results compiled revealed that Milastin-K@ 2.0 ml/L each by spraying + soil drenching monthly at root zone recorded less bacterial blight disease severity (22.75 PDI each) on leaves and fruits with 61.20% and 54.16% disease control over untreated control (58.63 PDI and 49.63 PDI) respectively. Similarly, the same treatment recorded less PDI on leaves (36.81) and fruits (16.59) as compared to control (63.82 and 30.41) respectively with 43.56% and 45.45% disease control respectively for control of anthracnose disease on leaves and fruits giving 15.21 T/ha yield as compared to POP (11.71 T/ha) which is 29.88% more than POP treatment. Similarly, there was no phytotoxicity in terms of leaf chlorosis, wilting, vein clearing, leaf tip burning, leaf necrosis and leaf epinasty.

Onion tip burn: Significance, and response to amount and form of nitrogen

Leaf tip burn in onion is a symptom of a number of biotic and abiotic stresses. It may appear in densely cultivated nursery transplants owing to one or the other simple or complex reasons. The present research work was planned to know the impact of rate and form of nitrogen (N) on post-transplantation recovery of tip burnt transplants, and significance of the disorder. Tip burn transplants were cultivated on sand culture hydroponic system at 0, 4, 6 and 8 mM N. In second trial 4 mM N was maintained in nutrient solution as 4:0, 3:1, 2:2 and 0:4 mM NO3-N: NH4-N ratios. N supply linearly increased total leaf length (TLL). Both high and low N levels and replacement of NO3-N with NH4-N in solution significantly increased burnt leaf length (BTL). Lowest BTL and highest bulb yield was noted at 4 mM N and at 4:0 mM NO3-N : NH4-N ratio. N induced increase in TLL significantly reduced BTL by 42% at 60 and 75 days after transplanting (DAT). In both the trials BTL, particularly at early growth stages, was linearly and negatively linked to bulb yield of onion. Depending upon the DAT, the suggested linear regression models described about 50% variation in bulb yield counted for BTL. It is concluded from the results that leaf tip burning in onion is of great importance regarding bulb yield and a reasonable recovery is possible through appropriate dose of nitrate nitrogen.

Mass screening for salinity tolerance in rice (Oryza sativa. L) genotypes at early seedling stage by hydroponics

Salinity is a major abiotic factor that affects rice cultivation in the world along the coastal areas. The salt affected areas in India is estimated to be around 8 to 10 million hectares that causes significant reduction in rice growth and yield. In order to improve the rice cultivars for salt tolerance, selection of the suitable genotypes is necessitated. Hence, in this experiment ninety seven rice genotypes including traditional landraces were collected and subjected to screening under salt stress by hydroponics system on Yoshida nutrient solution of EC 8 dSm−1and 12 dSm−1 with 4 replications. The genotypes were scored on 15th day after sowing based on standard evaluation scoring system of IRRI. Among the 97 rice genotypes scored, 5% were tolerant, 21% were moderately tolerant, 54% genotypes were susceptible and 18% were highly susceptible. The rice genotypes viz., Pokkali, FL478, Kuliyadichan, Gurukot and IR12L-107 revealed significant level of tolerance to salt stress. The rice genotypes, Pokkali and FL478 showed no symptoms at 8 dSm−1 and leaf rolling alone at 12dSm−1. Kuliyadichan, Gurukot and IR12L-107 showed leaf rolling at 8dSm−1 and leaf rolling and leaf tip burning at 12dSm−1. Screening of the rice genotypes for salinity tolerance only by visual symptoms is not reliable and hence the selected rice genotypes will further be characterized based on the morphological and biochemical parameters under salt stress in order to select elite salt tolerant rice genotypes for use in developing salinity tolerant somaclones by in vitro culture.

Evaluation of genotypic variation for growth of rice seedlings under optimized hydroponics medium

Although rice (Oryza sativa L.) is a semi-aquatic plant, its growth in solution culture is often problematic. In commonly used rice hydroponics media, plants exhibited mild nitrogen deficiency, leaf tip burn, salt deposition, along with zinc and iron deficiency. Therefore, we aimed to optimize the nutrient media for growing rice plants taking into consideration the nutrient concentration, pH and ratio of NH4 + to NO3 – nitrogen (N) and named it as ‘Pusa Rice Hydroponics’ (PusaRicH). PusaRicH contains higher amounts of macronutrients, significantly lower B, Mn and Cl and higher amounts of Zn than two commonly used hydroponics media, ‘Yoshida’ and ‘Kumura B’. The optimal ratio of NH4 + to NO3 – – N in PusaRicH medium was 0.5 mM NH4 + and 7.0 mM NO3 – with pH 5.0. The PusaRicH medium was validated by growing 100 diverse rice genotypes and it significantly outperformed the widely cited ‘Yoshida’ and ‘Kimura B’. Cluster analysis carried out on the squared Euclidean distance matrix of biomass and leaf area values of genotypes revealed four major clusters in all hydroponics medium. However, only PusaRicH medium resulted in ten genotypes as good performers in comparison to other two widely cited media. Therefore, the optimized PusaRicH medium can be used successfully to grow rice seedlings in hydroponic system which will aid in screening large number of genotypes in breeding and other physiological experiments.

Barley yellow dwarf virus Infection Leads to Higher Chemical Defense Signals and Lower Electrophysiological Reactions in Susceptible Compared to Tolerant Barley Genotypes.

Barley yellow dwarf virus (BYDV) is a phloem limited virus that is persistently transmitted by aphids. Due to huge yield losses in agriculture, the virus is of high economic relevance. Since the control of the virus itself is not possible, tolerant barley genotypes are considered as the most effective approach to avoid yield losses. Although several genes and quantitative trait loci are known and used in barley breeding for virus tolerance, little is known about molecular and physiological backgrounds of this trait. Therefore, we compared the anatomy and early defense responses of a virus susceptible to those of a virus-tolerant cultivar. One of the very early defense responses is the transmission of electrophysiological reactions. Electrophysiological reactions to BYDV infection might differ between susceptible and tolerant cultivars, since BYDV causes disintegration of sieve elements in susceptible cultivars. The structure of vascular bundles, xylem vessels and sieve elements was examined using microscopy. All three were significantly decreased in size in infected susceptible plants where the virus causes disintegration of sieve elements. This could be associated with an uncontrolled ion exchange between the sieve-element lumen and apoplast. Further, a reduced electrophysiological isolation would negatively affect the propagation of electrophysiological reactions. To test the influence of BYDV infection on electrophysiological reactions, electropotential waves (EPWs) induced by leaf-tip burning were recorded using aphids as bioelectrodes. EPWs in infected susceptible plants disappeared already after 10 cm in contrast to those in healthy susceptible or infected tolerant or healthy tolerant plants. Another early plant defense reaction is an increase in reactive oxygen species (ROS). Using a fluorescent dye, we found a significant increase in ROS content in infected susceptible plants but not in infected tolerant plants. Similar results were found for the phytohormones abscisic acid and three jasmonates. Salicylic acid levels were generally higher after BYDV infection compared to uninfected plants. Heat stimulation caused an increase in jasmonates. By shedding light on the plant defense mechanisms against BYDV, this study, provides further knowledge for breeding virus tolerant plants.

Effects of nutrient supply on production and quality of cut flowering branches ofGrevillea“Spiderman”

The irrigation and fertilization regime of different varieties of Grevillea in Israel are based on existing knowledge for growing various varieties of the Proteaceae family for production of cut flowering branches. However, growers face problems in cultivating Grevillea “Spiderman,” such as leaf chlorosis, prolonged growth until flowering, and reduced quality of cut flowering branches. The present study aimed to examine whether these problems stem from deficiency or excess of Fe, Mn, Zn, P, and Mg, focusing on the effect of these nutrients on growth, flowering, and appearance of visual leaf symptoms and on yield, quality, and vase life longevity of cut flowering branches. The nutrient treatments significantly affected plant development and flowering. Increasing the Fe concentration from 1 to 2 or 3 mg l –1 resulted in improved leaf color, from slightly yellow to dark green. The combination of 2 mg l –1 Fe + 1.8 mg l –1 Mn resulted in early flowering, highest yield, and development of long lateral branches. Low levels of P caused in the first year of treatment leaf chlorosis, which was intensified during the third year, resulting in severe yellowing of the flowering branches. Leaf necrosis and tip burn appeared in treatments with high concentrations of Zn, Mn, and Mg. Deficiency of Fe and Mn and high concentration of P and Mg led to the development of a large number of branches without flowers. The optimal fertilization treatment that yielded the highest quality of flowering branches after harvest was 2 mg l –1 Fe. Branches of this treatment had green foliage at harvest and the longest vase life (10 days) following the recommended postharvest treatment and air transport simulation. Based on the findings of the present research, it can be concluded that the problems in the cultivation of G . “Spiderman,” such as leaf chlorosis, delayed flowering, and reduced quality of flowering branches, result from improper fertilization.

Study of bio-efficacy and Phytotoxicity of New Generation Herbicides on Triafamone and Ethoxysulfuron in Direct Seeded Rice (Oryza sativa)

The herbicides triafamone + ethoxysulfuron at (200g/ml/ha and 225 g/ml/ha) and triafamone (225 g/ml/ha) applied at 15 days after planting recorded the zero weed counts of individual species viz., grasses, sedges and broad leaf weeds, weed dry matter production and weed control index favoring to higher grain yield of (5.2 and 5.34 t/ha). Triafamone + ethoxysulfuron (175 g/ml/ha) recorded the least weed count, weed dry matter and cent percent weed control index recorded at 42 days after application (DAA). Ethoxysulfuron (150g/ml/ha) was next in order. No phytotoxicity symptoms was observed in the treatments including double the recommended dose of triafamone + ethoxysulfuron (450 g/ml/ha and 225 g/ml/ha) in respect of leaf chlorosis, tip burning, necrosis, epinasty, hyponasty, vein clearing, wilting and rosetting.

Ocimum sanctum leaf extract induces drought stress tolerance in rice

ABSTRACTOcimum leaves are highly enriched in antioxidant components. Thus, its leaf extract, if applied in plants, is believed to efficiently scavenge ROS, thereby preventing oxidative damage under drought stress. Thus, the present study was performed in kharif 2013 and rabi 2014 season to evaluate the effect of aqueous leaf extract of Ocimum sanctum against drought stress in 2 rice genotype under glass house conditions. Here we show that various morpho- physiological (chlorophyll fluorescence, leaf rolling score, leaf tip burn, number of senesced leaves and total dry matter) and biochemical parameters (proline, malondialdehyde and superoxide dismutase content) were amended by Ocimum treatment in both the seasons. Application of Ocimum extract increased expression of dehydrin genes, while reducing expression of aquaporin genes in drought stressed rice plant. Thus, application of Ocimum leaf extract under drought stress can be suggested as a promising strategy to mitigate drought stress in economical, accessible and ecofriendly manner.

Dose-dependent response of Trichoderma harzianum in improving drought tolerance in rice genotypes.

This study demonstrates a dose-dependent response of Trichoderma harzianum Th-56 in improving drought tolerance in rice by modulating proline, SOD, lipid peroxidation product and DHN / AQU transcript level, and the growth attributes. In the present study, the effect of colonization of different doses of T. harzianum Th-56 strain in rice genotypes were evaluated under drought stress. The rice genotypes treated with increasing dose of T. harzianum strain Th-56 showed better drought tolerance as compared with untreated control plant. There was significant change in malondialdehyde, proline, higher superoxide dismutase level, plant height, total dry matter, relative chlorophyll content, leaf rolling, leaf tip burn, and the number of scorched/senesced leaves in T. harzianum Th-56 treated rice genotypes under drought stress. This was corroborated with altered expression of aquaporin and dehydrin genes in T. harzianum Th-56 treated rice genotypes. The present findings suggest that a dose of 30 g/L was the most effective in improving drought tolerance in rice, and its potential exploitation will contribute to the advancement of rice genotypes to sustain crop productivity under drought stress. Interaction studies of T. harzianum with three aromatic rice genotypes suggested that PSD-17 was highly benefitted from T. harzianum colonization under drought stress.

Treatment of Total Dissolved Solids from Plastic Industrial Effluent by Halophytic Plants

Eight halophytic plant species, Avicennia marina, Avicennia alba, Bruguiera gymnorrhiza, Lumnitzera racemosa, Rhizophora mucronata, Rhizophora apiculata, Suaeda maritima, and Xylocarpus moluccensis were evaluated for the removal ability of total dissolved solids (TDS) from plastic industrial effluent. All halophytic plants could tolerate and survive when grown in wastewater with high TDS. Among the test plants, S. maritima showed the highest TDS removal capability and was selected for further study. S. maritima had ability not only for TDS removal, but also for reduction of pH, electrical conductivity, and salinity from wastewater effluent under soil conditions. S. maritima did not exhibit symptoms such as necrosis and leaf tip burn during the experimental period. These results indicated that S. maritima has tolerance to high TDS and salinity. However, S. maritima responded to high TDS stress by producing proline and total sugar in the roots, stems, and leaves which indicated that this plant can adapt to wastewater with high TDS. In addition, silicon (Si) and calcium (Ca) were increased in the leaves due to plant stress from TDS. Therefore, S. maritima is suitable halophytic plants for treatment of TDS contaminated wastewater.

Field Evaluation of Rice Genotypes from the Two Cultivated Species (Oryza sativa L. and Oryza glaberrima Steud.) and Their Interspecifics for Tolerance to Drought

ABSTRACTA total of 327 rice (Oryza spp.) genotypes were screened for tolerance to drought at the Africa Rice Center in Cotonou, Benin, in 2007 and 2008. Plants were subjected to full irrigation from sowing to harvest or to 21‐d drought from 34 d after sowing. Drought‐affected plants showed narrower leaves, reduced grain yield, and shorter stature. Tillering and plant maturity were negatively affected by drought whereas values for leaf temperature and leaf greenness were significantly higher under drought than under control condition. Under control condition, for 54% of genotypes, flowering occurred between 71 and 90 d after sowing. But under drought, flowering occurred at 90 or more days after sowing for the majority of genotypes. Significant genotype × environment interactions were observed for plant height, leaf greenness, flowering, grain yield, maturity, leaf rolling, and leaf tip burning. More traits were correlated with grain yield under drought for Oryza glaberrima Steud. than for other genotype groups. No relationship was observed between plant recovery ability and all other traits selected. More than 90% of plants evaluated resumed growth after drought in both years. TOG6208, TOG5691, TOG5591, TOG6594, and RAM122 were identified as best performing genotypes in terms of grain yield under drought. Their performance was similar to that of most of the 24 top yielding in terms of leaf rolling, leaf tip burning, and plant recovery after drought release.

Increase of leaf tipburn in chervil and lettuce by restricting volume of growing medium

The objective of this investigation was to examine the effect of restriction of growing medium volume on the level of tipburn in chervil and leaf lettuce. Chervil: The plants were grown in different sizes of rock wool cubes: a. 31 cm3, b. 64 cm3, c. 135 cm3. The incidence of tipburned leaves decreased by increasing the size of cubes. Leaf lettuce: Plants were grown in different sizes of pots: 12 cm pots with capacity of 0.6 L and 8 cm pots with capacity of 0.25 L. The incidence of tipburned leaves increased by decreasing pot size.