Greater Shoot Fresh Weight Research Articles

Daily irrigation attenuates xylem abscisic acid concentration and increases leaf water potential of Pelargonium × hortorum compared with infrequent irrigation.

The physiological response of plants to different irrigation frequencies may affect plant growth and water use efficiency (WUE; defined as shoot biomass/cumulative irrigation). Glasshouse-grown, containerized Pelargonium × hortorum BullsEye plants were irrigated either daily at 100% of plant evapotranspiration (ET) (well-watered; WW), or at 50% ET applied either daily [frequent deficit irrigation (FDI)] or cumulatively every 4 days [infrequent deficit irrigation (IDI)], for 24 days. Both FDI and IDI applied the same irrigation volume. Xylem sap was collected from the leaves, and stomatal conductance (gs ) and leaf water potential (Ψleaf ) measured every 2 days. As soil moisture decreased, gs decreased similarly under both FDI and IDI throughout the experiment. Ψleaf was maintained under IDI and increased under FDI. Leaf xylem abscisic acid (ABA) concentrations ([X-ABA]leaf ) increased as soil moisture decreased under both IDI and FDI, and was strongly correlated with decreased gs , but [X-ABA]leaf was attenuated under FDI throughout the experiment (at the same level of soil moisture as IDI plants). These physiological changes corresponded with differences in plant production. Both FDI and IDI decreased growth compared with WW plants, and by the end of the experiment, FDI plants also had a greater shoot fresh weight (18%) than IDI plants. Although both IDI and FDI had higher WUE than WW plants during the first 10 days of the experiment (when biomass did not differ between treatments), the deficit irrigation treatments had lower WUE than WW plants in the latter stages when growth was limited. Thus, ABA-induced stomatal closure may not always translate to increased WUE (at the whole plant level) if vegetative growth shows a similar sensitivity to soil drying, and growers must adapt their irrigation scheduling according to crop requirements.

Tissue culture production of hazelnut – disinfestation and impact of agar content

Australian hazelnuts are a new and emerging industry with the potential annual value in Tasmania alone estimated to be in the order of $ 10-15 million. Currently tree propagation is a slow and inefficient process with suckers collected from mature trees and grown on in nurseries. This parent material may harbour diseases and pests and surviving progeny may have inconsistent growth rates, undesirable suckering and non-uniform growth habits, making orchard establishment challenging. The development of tissue culture technologies for hazels has been pioneered in Oregon, USA, resulting in new cultivars and improved planting stock underpinning successful industry establishment in the USA. There has been little success with tissue culture production of local cultivars in Australia. This project examined strategies to optimise the transfer of glasshouse and field grown cuttings (explants) into axenic tissue culture, by testing different disinfestation treatments with sodium hypochlorite (NaOCl). Further, once in tissue culture, we tested the impact of varying agar content in media on key growth parameters. Outcomes indicated fungal and bacterial contamination from field-sourced explants was greater than those from glasshousesourced and that a greater NaOCl concentration (2.1% compared to 1.05%) was required to obtain axenic tissue cultures. Also, low agar content (0.2-0.4%) in tissue culture media produced improved hazel explant growth with greater shoot fresh weights and node numbers than with high agar content. These findings may help underpin the development of micro-propagation as a useful source of quality planting material for the hazelnut industry in Australia.

Mitigation of Salt Stress in Lettuce (Lactuca sativa L. var. Crispa) by Seed and Foliar 24-epibrassinolide Treatments

The objective of this study was to determine the effect of 24-epibrassinolide (24-EBL) applications on growth, chlorophyll, and mineral content of lettuce (Lactuca sativa L. var. Crispa) grown under salt stress. The study was conducted in pot experiments under greenhouse conditions. Lettuce seedlings were treated with seed and foliar 24-EBL applications at different concentrations (0, 1, 2, and 3 μM). Salinity treatments were established by adding 0, 50, and 100 mm of sodium chloride (NaCl) to a base complete nutrient solution. Results showed that salt stress negatively affected the growth and mineral content of lettuce plants. However, seed and foliar applications of 24-EBL resulted in greater shoot fresh weight, shoot dry weight, root fresh weight, and root dry weight as well as higher stem diameter than the control under salt stress. Salinity treatments induced significant increases in electrolyte leakage of plant, but foliar 24-EBL application reduced leaf electrolyte leakage and has determined lower values of leaf electrolyte leakage than non-treated ones. In regard to nutrient content, it can be inferred that 24-EBL applications increased almost all nutrient content in leaves and roots of lettuce plants under salt stress. Generally, the greatest values were obtained from 3 μM 24-EBL application. Treatments of 24-EBL alleviated the negative effect of salinity on the growth of lettuce.

Factors Affecting the Growth of Microgreen Table Beet

There are very few reports on the production of microgreens, a new category of salad crops, the shoots of which are harvested at the seedling stage. A series of cultural studies was conducted with the objective of lessening greenhouse production time and lowering production costs of microgreen table beet (Beta vulgaris L.). Sowing seed balls at a commercially recommended rate (201 g·m−2; 11,256·seed balls·m−2) resulted in greater shoot fresh weight·m−2 at 15 days after planting than sowing seed balls at lower rates, although individual shoots were lighter. Sowing seed balls that were germinated before sowing (pregerminated) in fine-grade exfoliated vermiculite moistened with 150% water (wt. per vermiculite dry wt.) for 5 days at 20°C resulted in 26% greater shoot fresh weight·m−2 at 15 days after planting than sowing nontreated seed balls. Combining preplanting fertilization of the peat-lite with calcium nitrate at 2000 mg·L−1 of N (150 mL·L−1of medium) with daily postplanting solution fertilization with 150 mg·L−1 of N led to a further increase in shoot fresh weight·m−2 of 21% (nontreated seed balls) and 22% (pregerminated seed balls) compared to other fertilization regimes (excluding the check). Germinating, and extruding, seed balls in hydrophilic polymer (hydroxyethyl cellulose gel) advanced microgreen growth but not to the extent achieved with vermiculite as the pregermination medium. Irrespective of seed ball treatment, producing microgreens in troughs using the hydroponic nutrient film technique, compared to production in trays containing peat-lite, increased shoot fresh weight·m−2. Depending on seed ball treatment, economic yield was increased 33% to 98% by 7 days after planting and 75% to 144% by 15 days after planting. The greatest shoot fresh weight·m−2 at 15 days after planting (10.14 kg·m−2) was achieved using seed balls pregerminated in moist vermiculite and subsequent growth using the nutrient film technique.

Cultural practices to speed the growth of microgreen arugula (roquette; Eruca vesicaria subsp. sativa)

SummaryMicrogreens are salad crop shoots harvested for consumption within 10 – 20 d of seedling emergence. A series of cultural experiments was conducted with the objective of lessening the greenhouse production time, and therefore the production cost, for microgreen arugula (Eruca vesicaria subsp. sativa) grown in peat-lite (a soilless medium). Sowing seeds at a high rate (55 g m–2) resulted in a greater shoot fresh weight (FW) m–2 at 10 d after planting (DAP) than sowing at lower rates, although individual shoots were lighter. Two fertilisation regimes were examined: pre-plant incorporation of 500 – 4,000 mg N l–1 supplied as ammonium nitrate, calcium nitrate, ammonium sulphate, or urea, and/or post-emergence daily fertilisation with solutions of 21-2.2-16.6 (N-P-K) at 0, 75, or 150 mg N l–1. The two most economical fertilisation treatments to increase shoot FW m–2 were daily solution fertilisation with 150 mg N l–1, or daily solution fertilisation with 75 mg N l–1 plus a pre-plant media incorporation of 1,000 mg N l–1 from Ca(NO3)2. Irrespective of these two fertilisation treatments, pre-sowing germination (pre-germination) of seed by incubation in grade-5 exfoliated vermiculite (1.12 g seed in 157 g vermiculite) moistened with 2 gwater g–1 dry weight (DW) vermiculite for 1 d at 20°C, resulted in a 21% increase in shoot FW by 14 DAP compared to sowing non-treated seed. Pre-germinated seed showed 81.5% germination, with radicles averaging 2 mm in length at the time of sowing.

Salicylic acid ameliorates the adverse effect of salt stress on strawberry

Strawberry is considered as a salinity sensitive species and is adversely affected in response to the salt stress in terms of growth and yield. Pot experiments were conducted to determine the effect of exogenous salicylic acid (SA) application on physiology, growth, chlorophyll and mineral content of strawberry grown under salt stress and greenhouse conditions. Strawberry plants were treated with SA at different concentrations (0.0, 0.25, 0.50 and 1.00 mM). Salinity treatments were established by adding 0 and 35 mM of NaCl to a base complete nutrient solution. Salt stress negatively affected the growth, chlorophyll content and mineral uptake of strawberry plants. However, plants treated with SA often had greater shoot fresh weight, shoot dry weight, root fresh weight and root dry weight as well as higher chlorophyll content under salt stress. The greatest values were obtained with 1.00 mM SA treatment in both saline and non-saline conditions. Leaf water relative content (LWRC) was reduced in response to salt stress while electrolyte leakage was raised. SA treatments induced increases in LWRC and decreases in electrolyte leakage compared to the control under salt stress. With respect to the nutrient content, SA treatments increased almost contents of all nutrients in leaves and roots of strawberry plants under salt stress. The greatest values were often obtained by the 1.00 mM SA treatment. These findings suggest that the SA treatments can ameliorate the negative effect of salinity on the growth of strawberries.

Creation of salt tolerant wheat doubled haploid lines from wheat × maize crosses

Salinity is one of the most serious agricultural problems throughout the world. The objectives of these studies were: 1. to determine if salt tolerance can be enhanced by combining characters related to salt tolerance (salt exclusion, and high growth rate and grain yield in saline conditions) and 2. to study the genetic basis of salt tolerance in doubled haploid (DH) lines developed using wheat (Triticum aestivum L.) × maize (Zea mays L.) crosses. The 47 DH lines in experiment 1 and 22 DH lines in experiment 2 and their parents were grown in a controlled environment cabinet in nutrient solution with or without addition of 150 mM NaCl. Under the saline condition, the DH lines mean was significantly higher than mid-parental values for shoot fresh weight (SFW), shoot dry weight (SDW), root fresh weight (RFW), whole plant fresh weight (PFW), plant height (PH), number of tillers per plant (TNP), number of spikelets per spike (SNS), number of grains per spike (GNS), grain yield per plant (GYP), 100-grain weight (GW) and plant biomass (PB). Some DHs showed trangressive segregation for salt tolerance as determined by greater SFW, SDW, RFW, PFW, PH, TNP, SNS, GNS, GYP, GW and PB than the better parent. The genetic variances were greater than the error variances for all measured characters except K content in saline conditions. Moderate to high heritability estimates were found for all the characters studied in saline and control conditions. Salt exclusion was an important aspect of salt tolerance as Na content of leaves was negatively correlated with all growth characters at an early stage of growth, and with grain yield and yield components. We concluded that the higher salt tolerance of some DHs was due to the combination of genetic characters responsible for salt tolerance and salt tolerance is an inherited character.

Effect of Foliar Salicylic Acid Applications on Growth, Chlorophyll, and Mineral Content of Cucumber Grown Under Salt Stress

ABSTRACT The objective of this study was to determine the effect of foliar salicylic acid (SA) applications on growth, chlorophyll, and mineral content of cucumber grown under salt stress. The study was conducted in pot experiments under greenhouse conditions. Cucumber seedlings were treated with foliar SA applications at different concentrations (0.0, 0.25, 0.50, and 1.00 mM). Salinity treatments were established by adding 0, 60, and 120 mM of sodium chloride (NaCl) to a base complete nutrient solution. The SA was applied with spraying two times as before and after transplanting. Salt stress negatively affected the growth, chlorophyll content and mineral uptake of cucumber plants. However, foliar applications of SA resulted in greater shoot fresh weight, shoot dry weight, root fresh weight, and root dry weight as well as higher plants under salt stress. Shoot diameter and leaf number per plant increased with SA treatments under salt stress. The greatest chlorophyll content was obtained with 1.00 mM SA treatment in both saline and non-saline conditions. Leaf water relative content (LWRC) reduced in response to salt stress while SA raised LWRC of salt stressed cucumber plants. Salinity treatments induced significant increases in electrolyte leakage. Plants treated with foliar SA had lower values of electrolyte leakage than non-treated ones. In regard to nutrient content, it can be interfered that foliar SA applications increased almost all nutrient content in leaves and roots of cucumber plants under salt stress. Generally, the greatest values were obtained from 1.00 mM SA application. Based on these findings, the SA treatments may help alleviate the negative effect of salinity on the growth of cucumber.

Seed treatments to advance greenhouse establishment of beet and chard microgreens

SummarySeed treatments to advance the establishment of table beet or chard (Beta vulgaris L.) for greenhouse microgreen production were examined. While germination percentage was little affected, appreciable germination advancement in both crops was achieved using all seed treatments of matric priming (–1 MPa at 12°C for 6 d in fine vermiculite) or various soaks (water, 20°C for 48 h; hydrogen peroxide, 0.3% at 20°C for 48 h; hydrogen chloride, 0.3 M at 20°C for 2 h; or sodium hypochlorite, 4% at 20°C for 3 h). The most pronounced seedling emergence advancement, however, was gained by germinating seeds in fine grade vermiculite and sowing the germinated seed plus vermiculite mixture. No additional advancement in seedling emergence or growth was achieved by priming or soaking the seeds in hydrogen peroxide before germinating the seeds in the vermiculite. Germinating the seeds in shallow (c 4 cm deep) vermiculite (150% initial water, c 1 seed :3 vermiculite dry weight ratio, 27°C) for 2 d (table beet) or 3 d (chard) resulted in 0.33-fold and 2.79-fold greater shoot fresh weight, respectively, at 11 d after planting than was achieved by sowing untreated seeds.

Genotypic Differences in the Production and Partitioning of Carbohydrates Between Roots and Shoots of Wheat Grown under Zinc or Manganese Deficiency

Abstract The partitioning of soluble carbohydrates and starch between roots and shoots was investigated in wheat genotypes differing in Zn or Mn efficiency. The plants were grown for 11 d in a chelate-buffered nutrient solution with sufficient or deficient Zn and Mn supply. The Zn-efficient cultivar Warigal had a greater shoot fresh weight under sufficient Zn compared with the Zn-inefficient cultivar Durati. When supplied with sufficient Zn, Warigal had a greater concentration and content of soluble carbohydrates in roots and shoots in comparison with Durati. Under deficient Zn supply, Durati had a greater concentration and content of starch in roots and shoots compared with Warigal. In an experiment with varying supply of Mn, the Mn-efficient genotype C8MM had a greater shoot fresh weight than the Mn-inefficient cultivar Bayonet under sufficient or deficient Mn supply. The concentration of soluble carbohydrates in roots and shoots was decreased by deficient Mn supply in C8MM but not in Bayonet. Starch accumulated in the roots of Bayonet under deficient Mn supply. The results suggest that synthesis of carbohydrates is decreased under Zn deficiency, while they are preferentially partitioned to the roots to increase growth and thus the surface area available for Zn uptake. In the case of Mn deficiency, carbohydrate production was limited, but partitioning between roots and shoots was not altered.

Growth and Water Use of Tall Fescue as Influenced by Several Soil Drying Cycles1

AbstractMany investigations have studied various physiological processes using plants watered on a schedule with the effect of this watering schedule seldom considered significant. An understanding of the effect of watering frequency on growth and water use is required to understand water stress tolerance of tall fescue (Festuca arundinacea Schreb.). Experiments were designed to evaluate the effect of watering schedule in greenhouse grown tall fescue on growth, water use, and meristem tissue water status. Growth and water use as well as water, osmotic, and turgor potential of the leaf meristematic region were measured on tall fescue seedlings that had been exposed to several Maury soil (a fine, mixed, mesic Typic Paleudalfs) drying cycles (stressed and daily watered). Growth, measured as leaf extension rate (LER), was greater for seedlings watered to field capacity every 4th day than daily watered seedlings when soil of both treatments was allowed to dry. No significant difference in water potential or osmotic potential was observed during the experiment, and the differential LER was not dependent on turgor potential of the meristematic area which was similar to both treatments. Water use was 50 to 100% higher in control seedlings during the first 48 h of a soil drying cycle than in stressed seedlings. After several soil drying cycles the enhanced growth of stressed plants increased as high as 280%, then declined over the next 24 days of daily watering to about 50% above the control. The enhanced LER did not result in greater shoot fresh weights, but, repeated soil drying depressed root development. Consequently, growth, water status, and water use by tall fescue plants during an experiment must be evaluated in terms of the plants prior water stress history.