Increased Fruit Yield Research Articles

Effect of Hydrogen Cyanamide on Bud Break, Fruit Yield and Quality of Highbush Blueberry in Greenhouse Production

Highbush blueberries need sufficient chilling exposure to induce bud break and flowering, which limits their cultivation in warm areas as well as the profitability of protected cultivation in greenhouses. Hydrogen cyanamide (H2CN2, HC), gibberellic acid (GA3), ethephon (CE), mineral oil (MO), and potassium nitrate (KNO3) are often applied to deciduous fruit trees to advance bud break and fruit set. In this study, experiments were conducted in northeast China to determine the effects of different concentrations of HC or HC in combination with GA3, CE, MO, and KNO3 on bud break, fruit quality, and fruit yield in greenhouse-grown highbush blueberry (Vaccinium corymbosum L.). The results showed that all of the treatment agents could advance bud break by at least 15 days and fruit ripening by 16 days compared to the control. In addition, all treatments could promote the development of flowers and fruits and shorten the flowering and harvest periods. Compared with the control, 0.5% HC or 0.67% HC treatment increased the fruit yield of 5-year-old and 7-year-old bushes, especially early yield. Experiments carried out over two consecutive years in two different varieties, namely ‘M7’ and ‘Brigitta’, further confirmed the positive effect of 0.67% HC application on fruit yield. The results also showed that 0.67% HC had no negative effects on fruit quality. These findings may encourage growers to consider spraying HC in greenhouses to increase fruit yield, especially early yield, in order to schedule the harvest time for a more lucrative marketing period.

EFFECT OF PLANT GROWTH REGULATORS ON FRUIT SPLINTING IN THOMPSON NAVEL ORANGE

Fruit splitting is one of main problems extensively observed in citrus-growing area located in the northern parts of Iran. In order to investigate the effect of 2,4-D and GA3 on incidence of fruit splitting in Thompson ‘navel’ orange, an experiment, as a factorial arrangement in a randomized complete block design (RCBD) with three replications, was carried out in two consecutive years of 2016 and 2017. The main factors of this experiment included timing of spray at different growth stages (full bloom, petal fall, and June drop), 2, 4-D (0, 10, 20 mg L–1), and GA3 (0, 50, and 100 mg L–1). In the end of experiment, the characteristics including fruit length, fruit diameter, rind thickness, cellulase and polygalacturonase activities, total soluble solid, percentage of split fruit, and fruit yield were measured. Results showed that using 2, 4-D and GA3 not only decreased the rate of fruit splitting but also increased fruit yield as compared to controls. The highest fruit length, fruit diameter, rind thickness, total soluble solid and the lowest activities of cellulase and polygalacturonase were obtained using 100 mg L–1 GA3 and 20 mg L–1 2, 4 D during the full bloom. In general, the results revealed that using 2, 4-D and GA3 during the full bloom increased fruit yield while reduced fruit splitting and maintained the qualitative characteristics of Thompson ‘navel’ orange.

Co-composted Poultry Litter Biochar Enhanced Soil Quality and Eggplant Productivity Under Different Irrigation Regimes

The use of biochar has mostly moderate-positive to negative yield effects. However, integrating biochar with compost considerably enhanced biochar’s positive effects on crops. This study aimed to investigate the potential effects of co-composted poultry litter biochar incorporation under deficit irrigation on eggplant’s growth and productivity grown in salt-affected soil. Summer and fall season field experiments were conducted during 2016/2017. Three levels of co-composted biochar (CB) (0, 5, and 10 t ha−1) were used as a soil amendment combined with three irrigation levels (100, 80, and 60% of ETc). CB ameliorated the negative effects of water stress on eggplants, showing increased yield and irrigation water use efficiency (IWUE). This mainly due to the positive effect of CB on soil properties (i.e., bulk density, hydraulic conductivity, electrical conductivity, pH, useful pores%, water-holding pores%, available water, fine capillary pores%, and soil biota). The results showed that CB increased stomatal conductance, relative chlorophyll content (SPAD), and the photosynthetic efficiency of water-stressed eggplant at 80% ETc and consequently improved eggplant growth (i.e., leaf area, leaf number per plant, dry matter, stem diameter) and productivity. In summer and fall seasons, the highest fruit yields were recorded under full irrigation (28.3 t ha−1) and 10 t ha−1 of CB (27.8 t ha−1). Soil supplemented with 5 or 10 t ha−1 of CB increased IWUE by 31.6 and 64.1%, respectively, compared to CB-untreated soil. Adding 10 t ha−1 of CB under irrigation with 80% ETc increased fruit yield by 37% and IWUE by 69% in relation to full irrigation and CB-untreated soil. CB may be recommended as a soil amendment for vegetable crops such as eggplant to overcome the negative effects of water stress.

Influence of herbicides under biofertilizer application on fennel (Foeniculum vulgare) yield and quality with special reference to herbicide residues

BackgroundWeed occurrence and fertilization are considered two of the most factors influencing fennel yield. A two season’s field study was undertaken to investigate the response of fennel crop to two different herbicides under the application of biofertilizers. The two herbicides are pendimethalin (at reduced rate), fluazifop-p butyl and a combination of sequential application of both of them. The biofertilizers were used in 3 rates of 1:1:1, 2:1:1 and 1:1:2 (v/v/v) from atmospheric nitrogen-fixating, phosphorous-dissolving and potassium-solubilizing bacterial strains.ResultsThe results indicated that under all rates of the biofertilizers, the two herbicides applied individually caused significant reduction in growth parameters of the fennel plant estimated. Hand weeding (untreated check) increased fruit yield by 63% and oil yield by 78% compared to unweeded control, while sequential application of pendimethalin + fluazifop increased fruit yield by 45% and oil yield by 83% under biofertilizers at the rate of 2:1:1. Slight decrease in protein content using pendimethalin + fluazifop (12.94, and 12.96%) compared to 13.56% for hand weeding was observed. However, fluazifop alone showed no significant differences (13.63 and 13.13%) during both seasons under the biofertilizer rate of 2:1:1. No detectable residues of pendimethalin and fluazifop applied alone or sequentially were found in the analyzed dry seeds.ConclusionThe obtained results concluded that using proper level of biofertilizer combined with herbicides would increase the seed yield and oil content of fennel. Nevertheless, further investigation is needed to search for safer and effective weed control methods in medicinal plants.

Influence of nitrogen source on physiology, yield and fruit quality of young apricot trees

The objective of this two-year study was to assess the effect of N source on plant physiology, yield and fruit quality of apricot (Prunus armeniaca ‘Mogador’) trees. Parameters evaluated included: gas exchange [photosynthesis (Pn), transpiration (E), and stomatal conductance (gs)], chlorophyll content index (SPAD), leaf nutrient concentrations, fruit yield, total soluble solids (°Brix), acidity, sugar content (fructose, glucose, and sucrose), fruit color coordinates (L*, a*, b*), firmness, and radical scavenging activity. Trees were subjected to two N sources: ammonium nitrate [NH4 +/NO3 -(4/6)] applied as N-P2O5-K2O (18-18-18) and ammonium (NH4 +) applied as urea, with an annual application of 150 g N tree−1. In both years, apricot trees fertilized with NH4 +/NO3 - showed higher SPAD, macronutrient (N, P, K) concentrations, fruit yield and number than those treated with NH4 +. However, Pn, gs and E were similar for the two N treatments (NH4 +/NO3 -, NH4 +). Comparing with NH4 +, trees supplied with NH4 +/NO3 - exhibited an increase of 34% in total soluble sugars, 39% in firmness, 7% in scavenging capacity, 14% in fructose content, 31% in glucose content, 38% in sucrose content, 64% in the a* value, and 8% in the b* value. Sugar content (fructose, glucose, and sucrose), color coordinates, and firmness are the main contributors of fruit sweetness, sensory quality, and consumer or preference satisfaction. Since high marketable fruit yield is the main determinant for income returns by apricot producers, and considering that application of NH4 +/NO3 - (4/6) significantly increased fruit yield and sensory quality components, this N source should be preferred over NH4 source for commercial apricot production.

The first GM crop in Bangladesh – Bt Eggplant

Eggplant (Solanum melongena) commonly called Brinjal is the most popular vegetable in Bangladesh. It is extensively cultivated around homesteads and in commercial fields throughout the year. It is estimated that nearly 67 percent of the eggplant crop yield in Bangladesh is lost due to the damage caused by Leucinodes orbonalis also known as eggplant fruit and shoot borer (EFSB). EFSB is reportedly the most serious pest of eggplant. To overcome this EFSB problem Bt eggplant project has been initiated in 2004. The Agricultural Biotechnology Support Project II (ABSPII) is a USAID-supported project that has funded the development of Bt eggplant in Bangladesh under the Public Private Partnership (PPP) mode. Bangladesh Agricultural Research Institute (BARI) received the Event EE-1 eggplant in Mahyco and backcrossed into nine popular eggplant varieties of Bangladesh selected based on the regional consumer preference. The efficacy of cry1Ac gene in providing effective resistance to the target pest was also assessed in terms of productively (fruit yield increase) which was studied in 9 Bt eggplant lines for a period of 7 years from 2008 to 2015. To launch the best 4 varieties, BARI applied to the National Technical Committee on Crop Biotechnology (NTCCB). For release of GM crop variety, first of all follow the recommendation of NTCCB, then submitted to the National Technical Committee on Crop Biotechnology (NTCCB) Core Committee and then to the National Committee on Biosafety (NCB). The Bangladesh government approved four varieties namely, BARI Bt Begun-1 (Uttara), BARI Bt Begun-2 (Kazla), BARI Bt Begun-3 (Nayantara) and BARI Bt Begun-4 (BARI Begun-6 or ISD006) on 30 October 2013 and these got momentum countrywide. On 22 January 2014, Bt seedlings were distributed among 20 farmers in four districts of Bangladesh as the first genetically modified (GM) crops. After the government of Bangladesh approved the cultivation of Bt eggplant in 2013, its popularity is increasing day by day and the socio-economic condition of the farmers is also improving. Bt eggplant started its journey in 2014 with only 20 farmers, in seven years it has grown to about 27012 farmers and from 8 acres to about 5,000 acres. This advancement of Bt eggplant has also faced opposition from different quarters at different times. Today, the progress of Bt eggplant continues by overcoming all obstacles. Field days, trainings, various publications, documentary making, use of mass and social media, observations, workshops, stewardship activities are acting as important regulators of this progress.

Healthy Photosynthetic Mechanism Suggests ISR Elicited by Bacillus spp. in Capsicum chinense Plants Infected with PepGMV.

The aim of this study was to evaluate the effect of inoculation with Bacillus spp. isolates on the photosynthetic apparatus of Capsicum chinense plants infected with PepGMV. In vitro and greenhouse experiments were performed to evaluate whether the inoculation improved plants’ performance through the increase in photosynthetic efficiency to control PepGMV. The results showed that despite PepGMV infection, the plants inoculated with some isolates of Bacillus spp. had a healthy photosynthetic mechanism, as the photochemical parameters and gas exchange increased. The maximum photochemical quantum yield of PSII (Fv/Fm) of plants with PepGMV and inoculated with Bacillus isolates (M9, K46, and K47) increased (7.85, 7.09, and 7.77%, respectively) with respect to uninoculated controls. In inoculated plants, the CO2 assimilation rate increased and the transpiration rate decreased, therefore indicating an increased water use efficiency. This effect was reflected by the less severe symptoms caused by PepGMV in the plants obtained from seeds inoculated with different Bacillus spp. Plants inoculated with K47 isolates showed an increase in fruit yield and quality. This study suggests that it is possible to protect, at the greenhouse level, C. chinense plants from PepGMV through selected rhizobacteria inoculation.

Nano-Chelated Nitrogen Fertilizer as a New Replacement for Urea to Improve Olive Oil Quality

Different sources of nitrogen fertilizers are being used in olive orchards, of which urea is widely used by olive growers. However, nano-chelated nitrogen (nano-N) is a newly found feature of the fertilizer with very little known information. In the current research, the impact of foliar spray of two nitrogen sources; urea (U) and nano-N on oil content and quality of olive cv. ‘Zard’ during two consecutive seasons were investigated. The olive trees were sprayed with 2.21 g (U1) and 2.95 g (U2), and 6 g nano-N1 and 8 g nano-N2 at several phenological stages of olive tree. The detailed observations showed that U1 significantly increased fruit yield. Monounsaturated fatty acid and the ratio of oleic acid to linoleic acid were increased by the nitrogen treatments, especially with nano-N2, whereas it decreased in the case of saturated fatty acid and polyunsaturated fatty acids. The application of both fertilizer sources improved the leaf mineral compositions as well as the oil quality such as free fatty acids, peroxide activity, K232 and K270 extinction coefficients, the chlorophyll and carotenoid pigments. Total phenolic content of the oil in olive trees sprayed with urea was lower than those treated with nano-N. In contrast, the oil antioxidant capacity was high in those trees treated with nano-N. Overall, the results showed that nano-fertilizer, especially nan-N2 treatment rather than urea, is an effective approach to improve oil quality.

Combining ability analysis for quantitative traits in red sweet pepper (Capsicum annuum L. var. grossum Sendt.) grown under protected condition

Six red sweet pepper genotypes viz., RSPUHF-1, RSPUHF-2, RSPUHF-3, RSPUHF-4, RSPUHF-5 and RSPUHF-7 and their crosses using half-diallel excluding reciprocals were evaluated for combining ability to obtain desired hybrids. Analysis of variance for combining ability revealed that variances due to general combining ability (GCA) and specific combining ability (SCA) were highly significant for all the characters indicating the importance of additive and non-additive gene effects. RSPUHF-3 (‒1.42* and ‒1.5*) and RSPUHF-7 (‒1.25* and ‒1.54*) were found as reliable combiners for earliness and maturity. Whereas, the parents RSPUHF-1 (0.53*, 0.78*, ‒0.5, 0.12*, 0.25*), RSPUHF-2 (1.49*, 2.19*, 6.41*, 0.63*, 2.21*) and RSPUHF-4 (0.69*, 0.9*, 9.92*, 0.47*, 1.28*) were good general combiners for fruit set per cent, number of fruits per plant, fruit weight, fruit yield per plant and fruit yield per m2. Amongst, the crosses, RSPUHF-3 x RSPUHF-2 (0.95*), RSPUHF-4 x RSPUHF-2 (0.77*) and RSPUHF-5 x RSPUHF-2 (0.86*) were found to be the best specific combinations for increased fruit yield and component characters. Further, on the basis of per se performance it may be identified for release after multi location testing the above hybrids have been found to be the most promising for exploitation of heterosis.

Plant-Based Biostimulant as Sustainable Alternative to Synthetic Growth Regulators in Two Sweet Cherry Cultivars

Sweet cherry is a high value crop and the economic success of its cultivation depends not only on yield but also on fruit visual and nutritional quality attributes that influence consumer acceptability, as well as on fruit post-harvest performance and resistance to cracking. During the last few decades, cherry growers have tried to achieve these goals through exogenous applications of synthetic plant hormones and/or nutrients, but there is growing concern about the sustainability of the extensive use of these compounds in agriculture. For this reason, there is increasing interest in the possible adoption of different classes of biostimulants as sustainable alternatives to plant growth regulators. This research aimed to study the impact of foliar application of a novel tropical-plant extract, performed between full bloom and fruit set, on the yield and fruit quality of two important commercial sweet cherry cultivars, Kordia and Regina. The experimental design included a commercial control involving the application of a cytokinin promoter. In both cultivars, the tropical-plant extract induced significant increases in fruit yield. In addition, in the cultivar Kordia, the tropical-plant extract enhanced fruit calcium concentration, soluble solids content, flesh firmness, and skin color by 26.2%, 11.8%, 6.7%, and 12.0% (of fruits with mahogany skin color), respectively. Our results suggest that the tropical-plant extract tested as a biostimulant may be a sustainable and effective alternative to the exogenous application of synthetic hormones for sweet cherry cultivation.

Influence of Single and Combined Mixtures of Metal Oxide Nanoparticles on Eggplant Growth, Yield, and Verticillium Wilt Severity.

Verticillium wilt, caused by Verticillium dahliae, is one of the major diseases of eggplants. Nanoparticles (NPs) of CuO, Mn2O3, and ZnO were sprayed alone onto leaves of young eggplants and in different combinations and rates, and then seedlings were transplanted into soil infested with V. dahliae in the greenhouse and field between 2015 and 2018. All combinations of NPs were consistently less effective than CuO NPs applied alone at 500 µg/ml at increasing disease suppression, biomass, and fruit yield. CuO NPs were associated with an increase in fruit yield (17 and 33% increase) and disease suppression (28 and 22% reduction) in 2016 and 2017, respectively, when compared with untreated controls. However, this effect was negated in the greenhouse and field experiments when CuO NPs were combined with Mn2O3. Combining NPs of CuO with ZnO resulted in variable effects; amendments increased growth and suppressed disease in greenhouse experiments, but results were mixed in the field. Leaf tissue analyses from the greenhouse experiments showed that Cu concentration in leaves was reduced when CuO NPs were combined with other NPs, even when application rates were the same amount. A simple competition for entry sites may explain why combinations of CuO NPs and Mn2O3 NPs reduced efficacy but does not explain the lack of inhibition between Cu and Zn. NPs of CuO performed better than their larger bulk equivalent, and studies on application rate found 500 µg/ml was optimal. No phytotoxicity, as determined, by leaf burning, necrotic spots, or dead apical buds was noted even at the highest combined rates of 1,500 µg/ml.

Foliar Application of Zinc Oxide Nanoparticles Promotes Drought Stress Tolerance in Eggplant (Solanum melongena L.).

Water shortage and salinity are major challenges for sustaining global food security. Using nutrients in the nano-scale formulation including zinc oxide nanoparticles (ZnO NP) is a novel fertilization strategy for crops. In this study, two field-based trials were conducted during 2018 and 2019 to examine the influence of three ZnO NP concentrations (0, 50, and 100 ppm) in eggplant grown under full irrigation (100 of crop evapotranspiration; ETc) and drought stress (60% of ETc). Plant growth, yield, water productivity (WP), physiology, biochemistry, and anatomy responses were evaluated. Drought stress significantly decreased membrane stability index (MSI), relative water content (RWC), and photosynthetic efficiency, thus hampered eggplant growth and yield. In contrast, exogenous ZnO NP to water-stressed eggplant resulted in increased RWC and MSI associated with improved stem and leaf anatomical structures and enhanced photosynthetic efficiency. Under drought stress, supplementation of 50 and 100 ppm ZnO NP improved growth characteristics and increased fruit yield by 12.2% and 22.6%, respectively, compared with fully irrigated plants and nonapplied ZnO NP. The highest water productivity (WP) was obtained when eggplant was irrigated with 60% ETc and foliarly treated with 50 or 100 ppm of ZnO NP, which led to 50.8–66.1% increases in WP when compared with nontreated fully irrigated plants. Collectively, these findings demonstrated that foliar spraying ZnO NP gives the utility for alleviating drought stress effects on eggplant cultivated in saline soil.

Mulch Effect on Growth and Yield of Vine Vegetables

An experiment was undertaken to identify the suitable mulch paper for different high value vegetables during the winter season of November 2019 to March 2020 at the research farm of Olericulture Division, Horticulture Research Centre, Bangladesh Agricultural Research Institute, Gazipur, Bangladesh. The experiment was randomized complete block design with 3 replications. Three vegetables varieties viz., netted melon, watermelon, cucumber and 3 mulch treatments viz., T1=Silver over black mulch; T2= Black mulch; T3= No mulch were included in this study. Different vegetables responded differently with the changes of mulches irrespective of different characters. Considering relationship between the soil moisture content and fruit number it was clear that fruit number, average fruit weight, fruit length, fruit diameter was strongly related with soil moisture content. The effect of different plastic mulches on fruit weight per plant and yield (t/ha) were significant. Mulching produced higher fruit yield per plant and fruit yield per hectare than for the control, indicating that the mulch had positive effect in generating increased fruit yield. Silver over black plastic mulch produced the highest fruit yield viz., 24.22 t/ha (cucumber), 26.37 t/ha (netted melon), 43.59 t/ha (watermelon) followed by black and no mulches. Obviously, control plot produced the lowest fruit yield.

Impact of zinc and boron foliar application on fruit yield, nutritional quality and oil content of three pomegranate (Punica granatum L.) cultivars

Pomegranate (Punica granatum L.) productivity is largely governed by the growing condition and cultivar type. In this context a study was undertaken to find out the effect of zinc (Zn) and boron (B) foliar sprays on fruit yield, quality and seed oil content of three pomegranate cultivars viz. Bhagawa, Mridula and Ganesh. Zinc sulfate (0.30%), boric acid (0.25%) and zinc sulfate (0.30%) + boric acid (0.25%) were sprayed on selected trees thrice; at flower bud initiation, 15 and 45 days after blooming. Results showed that foliar sprays of Zn and B alone or in combination increased their concentration in leaves and consequently increased fruit yield. The effect was more pronounced with B than with Zn. Foliar treatment of these elements also significantly improved micronutrient concentration (Fe, Mn, Zn, Cu and B) in fruit. In addition, foliar fertilization of Zn led to significant improvement in fruit quality comprising of 2.84-8.87% increases in aril per cent, 7.84-10.72% increases in ascorbic acid, 0.71-17.48% increases in total phenol, 23.42-120.48% increases in anthocyanin and 30.73-55.30% increases in non-reducing sugar content, while B application resulted 5.09-16.98% increase in seed oil content. The highest level of seed oil content (29.63%) was recorded in cv. Mridula. In conclusion, foliar sprays of either zinc sulfate (0.30%) or boric acid (0.25%) could enhance the economic yield while zinc sulfate was superior in improving the nutritional quality and boric acid in increasing the seed oil content of pomegranate fruit in semiarid region.

Selenium Inhibits Cadmium Absorption and Improves Yield and Quality of Cherry Tomato (Lycopersicon esculentum) Under Cadmium Stress

The purpose of this study is to determine the effects of selenium (Se) on cherry tomato fruits under cadmium (Cd) stress. Methods: Se (2.5 μM) was applied to hydroponic solution with different concentrations of Cd (10 μM and 50 μM). The yield, quality, mineral elements, and Cd contents of cherry tomato was determined. Ten micromolars of Cd had no effect on the appearance and quality of cherry tomato, while 50 μM Cd significantly reduced the content of vitamin C, lycopene, soluble solids, and soluble sugars in the fruits. Cd stress significantly reduced cherry tomato fruit yield and also inhibited the accumulation of mineral elements such as calcium, magnesium, and iron in the fruits, and these inhibitory effects increased with the increase of Cd concentration. Besides, Se application significantly increased fruit yield by 8.38% and 8.56% under 10 μM and 50 μM Cd stress, respectively, when compared with plants grown without Se. Exogenous application of Se also significantly increased vitamin C, lycopene, and soluble sugar contents of fruit under 50 μM Cd stress and effectively promoted the accumulation of calcium, iron, copper, and zinc in the fruits. In addition, Se significantly reduced the Cd contents in roots, stems, and leaves of cherry tomato plants under 10 μM and 50 μM Cd stress, thereby leading to 12.85% and 12.48% respective decrease in the Cd content in fruits when compared with plants grown without Se. Therefore, applying Se can effectively improve the yield and quality of cherry tomato fruits under Cd stress and also reduce the Cd content in fruits.

Effect of Some Clean Agricultural Treatments on Fruit Yield, Active Ingredients and Chemical Composition of Ammi visnaga, L.

A field experiment was carried out at the Experimental Farm. of Fac. Agric. Minia Univ. during two seasons (2011/2012 and 2012/2013) to study the effect of compost (0, 5, 7.5 and 10 ton/fed.) and eight biostimulant treatments (E.M., S.A., vit. E, E.M. + vit. E, E.M. + S.A., S.A.+ vit. E, E.M. + S.A. + vit. E and control) on Ammi visnaga, L. plants. The data showed that using 10 ton/fed. compost significantly increased fruit yield /plant, khellin and visnagin contents and chemical composition (N, P and K %) comparing with other treatments. Treating plants with E.M., S.A., vit. E and all possible mixtures significantly increased fruit yield, active ingredients and percentages of N, P and K comparing with control treatment. The best treatments were E.M. + S.A. + vit. E following by E.M. + vit. E in this concern. It may be recommended to use compost at the level of 10 ton/fed. and treating the plants with the triple a mixture (E.M. + S.A. + vit. E) or the dual mixture (E.M. + vit. E) to give the highest values of fruit yield and active ingredients (khellin and visnagin) of Ammi visnaga plants.

Assessing the Impact of Higher Levels of CO2 and Temperature and Their Interactions on Tomato (Solanumlycopersicum L.).

Climate change has increasing effects on horticultural crops. To investigate the impact of CO2 and temperature at elevated levels on tomato production and quality of fruits an experiment was conducted by growing plants in open top chambers. The tomato plants were raised at EC550 (elevated CO2 at 550 ppm) and EC700 (elevated CO2 at 700 ppm) alone and in combination with elevated temperature (ET) + 2 °C in the open top chambers. These elevate CO2 and temperature treatment effects were compared with plants grown under ambient conditions. Outcome of the experiment indicated that growth parameters namely plant stature in terms of height (152.20 cm), leaf number (158.67), canopy spread (6127.70 cm2), leaf area (9110.68 cm2) and total dry matter (223.0 g/plant) were found to be high at EC700 compared to plants grown at ambient conditions in open field. The plants grown at EC700 also exhibited significantly higher number of flowers (273.80) and fruits (261.13), more fruit weight (90.46 g) and yield (5.09 kg plant−1) compared to plants grown at ambient conditions in open field. The percent increase in fruit yield due to EC varied from 18.37 (EC550) to 21.41 (EC700) percent respectively compared to open field and the ET by 2 °C has reduced the fruit yield by 20.01 percent. Quality traits like Total Soluble Solids (3.67 °Brix), reducing sugars (2.48%), total sugars (4.41%) and ascorbic acid (18.18 mg/100 g) were found maximum in EC700 treated tomato than other elevated conditions. Keeping quality was also improved in tomato cultivated under EC700 (25.60 days) than the open field (17.80 days). These findings reveal that CO2 at 700 ppm would be a better option to improve both quantitative as well as qualitative traits in tomato. Among the combinations, EC550 + 2 °C proved better than EC700 + 2 °C with respect to yield as well as for the quality traits. The tomato grown under ET (+2 °C) alone recorded lowest growth and yield attributes compared to open field conditions and rest of the treatments. The positive influence of EC700 is negated to an extent of 14.35 % when the EC700 combined with elevated temperature of + 2 °C. The present study clearly demonstrates that the climate change in terms of increased temperature and CO2 will have a positive effect on tomato by way of increase in production and quality of fruits. Meanwhile the increase in EC beyond 700 ppm along with ET may reduce the positive effects on yield and quality of tomato.

Gas Exchange Parameters, Fruit Yield, Quality, and Nutrient Status in Tomato Are Stimulated by ZnO Nanoparticles of Modified Surface and Morphology and Their Application Form

Nanoparticles (NPs) of ZnO are reported to enhance plant growth; however, during NPs syntheses, they tend to agglomerate, affecting their dispersion. Agglomeration can be counteracted if NPs surface is modified and/or they have the appropriate morphology. The objective of the present study was to assess the effects of the morphology, the surface modification, and the way of application of NPs-ZnO on tomato. Two NPs-ZnO morphologies (spherical or hexagonal) whose surface was modified with maltodextrine (MDX) or not, and applied to tomato plants via foliar sprays or drench at 1500 ppm were assessed. Hexagonal and spherical NPs increased plant growth, and fruit yield, quality and nutrient status, and gas exchange parameters. Fruit P, K, Ca, Mg, Mn, and Si were higher when hexagonal NPs-ZnO modified with MDX were applied by drench; however, Zn was higher when spherical or hexagonal no surface modified NPs were applied. The morphology of NPs, alone or combined with foliar or drench applications, did not affect fruit yield or quality. MDX applied alone increased fruit yield and quality. Nanoparticles of ZnO increased growth and yield, although spherical or hexagonal NPs produced similar results. Hexagonal nanoparticles applied by drench increased biomass when their surface was modified with MDX; however, even though fruit yield was not affected, drench applications of MDX-modified hexagonal NPs resulted favorable for macronutrient and Mn and Si status in the fruits. MDX had a biostimulant effect as it increased yield, quality of fruits, photosynthesis, transpiration, and nutrients status in fruits.

Foliar application and seed priming of salicylic acid affect growth, fruit yield, and quality of grape tomato under drought stress

Drought, an acute abiotic stress, limits growth and yields of crops including tomato. Salicylic acid (SA) has been widely used as an abiotic stress mitigating agent in various crops. Two experiments were conducted to assess the effects of SA applied as a foliar spray and as a seed priming material on growth, yield, and fruit quality of grape tomato under drought stress. In the first experiment, SA was applied as a foliar spray in five doses (0, 50, 100, 150, and 200 mg L–1) under three soil moisture regimes (50 %, 75 %, and 100 % field capacity [FC]). In the second experiment, doses of SA and soil moisture regimes were the same as first experiment, except that SA was applied as a seed priming material. Data on growth, fruit yield, and quality of grape tomato were collected. The results revealed that severe moisture deficit of 50 % FC adversely affected growth and fruit yield of grape tomato by 94 % in experiment 1 (foliar application of SA) and by 95 % in experiment 2 (seed priming of SA) compared with 100 % FC, while fruit quality parameters (fruit pH, total soluble solids, and color index) improved with reducing soil moisture regime. Exogenous application of SA at 150 mg L–1 as a foliar spray enhanced fruit yield by 41 % and at 100 mg L–1 as a seed priming material resulted in 33 % increase in fruit yield compared with the control. However, there was no effect of SA supplementation at severe moisture deficit of 50 % FC regardless of experiments and doses. Foliar application of SA at 150 mg L–1 resulted in statistically similar yields between moderate soil moisture level of 75 % FC and sufficient soil moisture level of 100 % FC, whereas in case of seed priming treatment, maximum fruit yield was obtained at 100 mg L–1 SA dose in combination with 100 % FC. Grape tomato yielded more with foliar application of SA (113.1 g plant–1 fruit yield at 150 mg L–1) than did with SA seed priming (87.8 g plant–1 fruit yield at 100 mg L–1). Exogenous application of SA at 150 mg L–1 as a foliar spray and at 100 mg L–1 as a seed priming material could be recommended when grape tomato is grown under moderate to sufficient soil moisture availability.

Evaluation of the control effect of SAR inducers against citrus Huanglongbing applied by foliar spray, soil drench or trunk injection

Huanglongbing (HLB) or greening disease, associated with the bacterial pathogen Candidatus Liberibacter asiaticus (Las), is currently the most devastating citrus disease worldwide and no cure is available. Inducers of systemic acquired resistance (SAR) are effective and sustainable to combat various plant diseases. In this study, the SAR inducers acibenzolar-S-methyl (ASM), imidacloprid (IMI), 2,6-dichloroisonicotinic acid (INA), and salicylic acid (SA), applied individually by foliar spray, soil drench or trunk injection at various rates and frequencies, were evaluated for control of HLB in a 3-year field trial with mature Hamlin sweet orange trees in central Florida, USA in the 2016, 2017, and 2018 crop seasons. Six foliar sprays, six soil applications, and three trunk injections of ASM, IMI, INA, or SA per year were conducted with the untreated as a negative control. HLB disease severity, Las titers, pre-harvest fruit drop, yield and fruit quality were investigated for the treatments. By the end of the 2018 season, all trunk injection treatments at 0.25 g/tree and foliar sprays of INA or SA (but not ASM or IMI) at 0.5 g/tree significantly reduced disease severity, Las population, and fruit drop, and increased fruit yield; whereas all foliar spray treatments at 0.25 g/tree, trunk injection treatments at 0.125 g/tree, and soil drench treatments at 0.25 or 0.5 g/tree did not provide effective control of HLB. Additionally, all trunk injection treatments at 0.25 g/tree had shown a significant decrease in fruit drop and increase of fruit yield starting from 2016 after 1 year of applications, whereas foliar sprays of INA or SA at 0.5 g/tree exhibited similar effects at 2018 after 3 years of applications. None of the SAR inducer treatments had significant effect on fruit quality. Economic analysis suggested that the trunk injection treatments at 0.25 g/tree might produce financial benefits. Overall, this study presents useful information for management of citrus HLB with SAR inducers.