Young Lemon Research Articles

NUTRITION OF YOUNG LEMON PLANTS IN THE OPEN FIELD

The article provides scientific data on the study of optimal norms and timing of leaf feeding in the care of young lemon seedlings in the open field. The care of young lemon seedlings in the open field focuses on the rapid growth of branches, enlargement of leaf surface and leaf activity. Due to the additional nutrition of the leaves, the growth and development of young lemon seedlings is accelerated, the leaf surface is cleaned of dust, which has a positive effect on the metabolism of the leaves, the process of respiration and photosynthesis in the leaves. As a result, young lemon seedlings grow well in the short term and are formed as seedlings ready for planting in the main area. KEYWORDS: lemon, seedling, seedling, twig, leaf surface, open area, air temperature, relative humidity, fertilizer, suspension, photosynthesis.

The possible role of extra magnesium and nitrogen supply to alleviate stress caused by high irradiation and temperature in lemon trees

Citrus trees are subjected to variation of environmental conditions throughout the annual cycle, especially during the flowering and fruit set. Heat waves have affected the environmental conditions required for optimum crop growth and have reduced fruit yield and quality worldwide. This study aimed to evaluate an extra supply of magnesium (Mg) and/or nitrogen (N) to increase citrus tolerance to excessive increased irradiation and consequent air temperature. Young lemon trees were grown in a greenhouse with extra Mg, N and Mg + N supply for five months and then exposed to heat for 12 days. After imposing stress condition, photosynthetic and enzymatic antioxidant system parameters were assessed to evaluate the impact of the extra nutrient supply in alleviating stress induced by combination of elevated irradiance and air temperature. Extra nutrient supply increased plant tolerance to the environmental stress, allowing maintenance of high photosynthetic and transpiration rates and low ratio of apparent electron transport rate per photosynthetic carbon assimilated. Enhanced Mg supply also increased activity of the antioxidant enzyme system and decreased the oxidative stress of plants. Trees treated with extra N exhibited increased chlorophyll concentrations and ability to harvest light energy. Citrus trees under stressed condition, such as elevated air temperature and radiation, associated to heat waves, exhibited less damage in the photosynthetic mechanism and high activity of the antioxidant enzymatic system when supplied with extra nutrient. It was concluded that extra Mg and N supply are important tools to prevent damages and enhance lemon trees biochemical and physiological responses to alleviate the harmful effects of unfavorable environmental condition.

Screening of the anthocyanin profile and in vitro pancreatic lipase inhibition by anthocyanin-containing extracts of fruits, vegetables, legumes and cereals.

The phytotherapic treatment of overweight and/or moderate obesity is growing widely, thus there is a great interest towards the phenolic compounds of fruits and vegetables which may inhibit pancreatic lipase enzyme. In this study, we report the chemical composition and in vitro pancreatic lipase inhibitory activity of 13 freeze-dried anthocyanin-containing extracts of different Mediterranean plants: fruits (blood orange, pomegranate, blackberry, mulberry and sumac), citrus by-products (blood orange peel), citrus vegetative tissues (young lemon shoots); vegetables (red cabbage and violet cauliflower), legume seeds (black bean), cereals (black rice), and cereal processing by-products (black rice hull). Total phenols and anthocyanins were determined. Individual anthocyanins were identified by UHPLC-PDA-ESI/MSn . Results revealed a wide variation in the distribution of anthocyanin compounds. Blood orange and pomegranate juice extracts had the highest total anthocyanin content and exhibited the strongest inhibition of pancreatic lipase in vitro. Inhibitory activity was positively correlated with anthocyanin content. In appropriate formulations, anthocyanin-containing extracts could find a use as anti-obesity agents. © 2016 Society of Chemical Industry.

Effects of different pruning modes on fruit yield and economic benefit of young lemon orchard

Young lemon(Citrus limon(L.) Burm. F.) tree with three year old was employed for researching the effects of different pruning modes(light thinning pruning, machinery pruning, heavy pruning) on the fruit yield and its economic benefit. The results showed that the fruit yield of spring-flowering lemon depended on pruning modes, from high to low, the order was light thinning pruning, machinery pruning and heavy pruning, and the economic benefit decreased from light thinning pruning, heavy pruning to machinery pruning in turn. The fruit yield and economic benefit of spring-flowering lemon were consistent. The economic benefits of spring-flowering lemon and the fine-fruit lemon were both declined from light thinning pruning, machinery pruning, to heavy pruning in turn, and the cost of pruning were followed on the order of heavy pruning, light thinning pruning, and machinery pruning. The total benefit was ordered by light thinning pruning,machinery pruning and heavy pruning. From the view of fruit yield and economic benefit, light thinning pruning, as a recommended mode, was the best one, while heavy pruning could seriously influence the fruit yield in the first year.

Population Structure and Growth of Young Lemon Shark, Negaprion brevirostris (Poey, 1868), at the Atol das Rocas Biological Reserve, Brazil

We conducted expeditions (N=16) to the Rocas Atoll Biological Reserve aiming study the lemon shark (Negaprion brevirostris) population. Youn...

Population size and survivorship for juvenile lemon sharks (Negaprion brevirostris) on their nursery grounds at a marine protected area in Brazil

Sharks face a number of obstacles for surviving their first several years of life and many species occupy nursery areas. Although estimates of survival, particularly for young age classes, are essential for assessing, monitoring and effectively managing animal populations, there have been relatively few calculations of survival within shark populations and even fewer estimates based on direct methods for sharks on their nursery grounds. We used tag-recapture methods to estimate the population size and survival of juvenile lemon sharks (Negaprion brevirostris) on their nursery grounds at Atol das Rocas, a marine protected area in Brazil. Sharks were sampled from1999 to 2003. Population size estimates ranged from 12 to 100 juvenile sharks and survival estimates ranged between 24-54% with a mean of 44.6% over the most robust sampling periods. The population of juvenile lemon sharks declined over the course of our study, whereas survival rates may have increased over the same time period. Even a modest level of fishing and removal of mature females in adjacent areas may dramatically affect small populations of sharks within a small and isolated nursery such as Atol das Rocas. The lower survival rates and population size at Atol das Rocas could be the result of differences in physical characteristics of this nursery in comparison to others used by lemon sharks in the northwestern Atlantic. Such comparatively lower populational parameters suggest that the population of young lemon sharks is fragile at the Atol das Rocas nursery.

Movement patterns of juvenile lemon sharks Negaprion brevirostris within Atol das Rocas, Brazil: a nursery characterized by tidal extremes

Movement patterns and habitat use of juvenile lemon sharks Negaprion brevirostris were monitored at Atol das Rocas, Brazil, an atypical nursery area for this species, characterized by extreme tides and a lack of seagrass flats and mangroves. Twenty-three sharks carrying transmitters were monitored using an array of bottom-fixed automated receivers during 3 trips over a total of 60 d. Transmitters were recorded on receivers over 13 000 times, and the majority of sharks were detected more than 100 times. Newborn sharks (60 to 80 cm total length, TL) showed restricted but repeated movements between small tide pools on reef flats at low tide and a small, shallow, nearby tidal creek at high tide. Larger sharks (up to 106 cm TL) sampled 6 and 20 mo after the study in March 2000 frequented the tidal creek and several other locations at high tide and a variety of larger pools at low tide, and in general exhibited more extensive movements within the atoll than did newborn sharks. Sharks approaching 2 yr of age were generally observed in specific pools or shallow water locations within the atoll during high and low tides, but also expanded their movements to include more of the atoll. Throughout the study, young lemon sharks appeared to concentrate movements within shal- low-water low-tide refuges and separate high tidal areas. Movement patterns of sharks in Atol das Rocas differ from those at other well-studied lemon shark nursery locations, where individuals con- tinuously occupy shallow flats and mangrove habitats. Nevertheless, lemon sharks in general restrict their movements to shallow-water habitats regardless of the specific nursery area occupied. This behavior is most likely related to predator avoidance. This study provides an example of the inter- action between the physical environment and the biology of animals—in this case, the influence of the physical characteristics of a nursery area and the behavioral ecology of young lemon sharks.

Improving water-use efficiency of young lemon trees by shading with aluminised-plastic nets

The experiment was carried out in a research field near Murcia, Spain, over a 3-week period between August 29 and September 17, 2001. Measurements obtained by the continuous monitoring of sap flow and parameters derived from trunk diameter fluctuations were compared with discrete measurements of conventional plant–water status indicators in potted young lemon trees ( Citrus limon (l.) Burm. Fil, cv. Verna) grafted on sour orange ( Citrus aurantium L.) rootstock. Eight trees were used in the experiment, four of which were placed under a rectangular shading net, while the other four were maintained in the open air. The decrease of sap flow in shaded trees with respect to the exposed trees was evident every day. The net also affected trunk diameter changes, with the shaded trees showing lower values of maximum daily shrinkage. High radiation reduced the leaf water potential. In the early morning, the shaded plants opened their stomata later than the plants growing in the open air, and so the transpiration in the latter was higher than in the former during the first hours of the day. However, the net photosynthesis rate was not increased in the exposed plants during these hours of the morning. In the central hours of the day, the leaf stomatal conductance values of exposed plants were lower, as were their instantaneous photosynthesis rates, than the corresponding values in the shaded trees. As a result of the photosynthesis/transpiration balance, it was observed that the best integrated daily water-use efficiency corresponded to the shaded treatment.

Comparison of continuously recorded plant-based water stress indicators for young lemon trees

Continuously recorded plant-based water stress indicators (sap flow and parameters derived from trunk diameter fluctuations) were compared in potted young lemon trees (Citrus limon (L.) Burm. fil, cv. Verna) grafted on sour orange (C. aurantium L.) rootstock submitted to deficit irrigation. Daily maximum (MXTD) and minimum (MNTD) trunk diameters and daily trunk diameter shrinkage (MDS) were directly influenced by the water supply to the trees from the soil. The continuously recorded plant-based water stress indicators presented different degrees of sensitivity when used to estimate the water status of the plants. Sap flow (SF) and MDS were more immediate and sensitive than MXTD and MNTD. However, the higher signal intensity: noise for SF and the fact that its signal intensities remained clearly above unity during the stress period, indicating that the soil water was depleted, point to the greater reliability of this indicator. Also, the possibility of developing further baseline relationships between SF and air vapour pressure deficit in fully irrigated trees in field conditions increases the feasibility of using this parameter in automatic irrigation systems.

Sap flow and trunk diameter fluctuations of young lemon trees under water stress and rewatering

Potted 2-year-old lemon trees ( Citrus limon (L.) Burm. fil, cv. Verna) grafted on sour orange ( C. aurantium L.) rootstock and growing under field conditions were subjected to water stress by withholding irrigation for 6 days. After that time, irrigation was restored and plant recovery was studied for 8 days. The results indicate that sap flow (SF) measurement by the heat-pulse technique is a suitable plant-based method for estimating the daily transpiration for young lemon plants. The most sensitive continuously recorded plant-based indicators of water stress and recovery were daily minimum trunk diameter (MNTD) and daily maximum trunk shrinkage (MDS) followed by SF. It was concluded that the water supplied to the trees from soil has a direct influence on daily MDS. Besides reflecting tree water status, SF and MNDT were clearly influenced by weather conditions, meaning that it is possible to develop reference or baseline relationships to interpret plant-based indicator measurements for irrigation scheduling.

Interpreting trunk diameter changes in young lemon trees under deficit irrigation

Measurements obtained by the continuous monitoring of sap flow and parameters derived from trunk diameter fluctuations were compared with discrete measurements of conventional plant water status indicators in potted young lemon trees ( Citrus limon (l.) Burm. fil, cv. Verna) grafted on sour orange ( C. aurantium L.) rootstock submitted to high frequency deficit irrigation. The first detectable response to the deficit irrigation was a marked increase in maximum daily trunk diameter shrinkage (MDS) followed by a decrease in sap flow (SF), predawn leaf water potential and leaf conductance values. Daily maximum (MXTD) and minimum (MNTD) trunk diameters were directly influenced by the plant water supply from the soil. When the water stress increased in severity and the trunk growth rate increased, the MDS values in treated plants decreased to reach values similar to those of control plants. Thus, during the first days of deficit irrigation, when trunk growth was very low, MDS and SF served as the best plant water status indicators. Further, when water stress was more pronounced and trunk growth was greater, MNTD, MXTD and SF were the most reliable indicators.

Selective Pruning of Young Lemon Trees to Increase Fruit Size

Growth of young lemon trees (Citrus limon Burm. f.) is extremely vigorous, and is characterized by the appearance of highly vigorous upright shoots that originate in the scaffold branches and trunk of the tree. While maturing, these shoots are considered to be in competition for photosynthates with smaller fruit in the spring and with mature fruit in the fall. During 1993 and 1994, we selectively removed these shoots 12, 6, 4, and 1 (1994 only) times per year, with the objective of increasing fruit size. Neither yield nor fruit quality was affected by the pruning treatments during 1993, but pruning trees 12 times per year increased fruit size by 30% compared to unpruned trees. In 1994, lemon trees pruned 4 times per year had 50% less cull fruit than unpruned trees, and 22% more fruit of size 140 or larger. However, >99% of the flowers and small fruit on trees pruned 4 times per year were aborted, compared with 95% abortion on the unpruned trees. Trees pruned 4 times per year also had 40% less yield compared with those that were unpruned.

Effect of ration size on growth and gross conversion efficiency of young lemon sharks, Negaprion brevirostris

Young lemon sharks, Negaprion brevirostris, were kept under controlled conditions in an aquarium and fed blue runner, Caranx crysos, at different ration levels. The relationship between feeding rate and growth rate was best described by a von Bertalanffy growth curve, which predicted a maximum growth rate of 140 kJ kg−1 day−1 (0·66% b.w. day−1), a maintenance ration of 199 kJ kg−1 day−1 (1·06% b.w. day−1), and losses due to starvation of ‐236kJ kg−1 day−1 (1·11% b.w. day−1). The relationship between gross conversion efficiency (K1) and feeding rate was also examined. K1 ranged from ‐ 64 to 25% and did not drop at high ration levels. Activity levels of both starved sharks and sharks fed at maintenance were not significantly different (0·2 body lengths s−1). K1 values generated from both laboratory and field data suggest that young lemon sharks can convert food to new tissue as efficiently as teleosts.

Effect of ration size on growth and gross conversion efficiency of young lemon sharks, Negaprion brevirostris

Young lemon sharks, Negaprion brevirostris, were kept under controlled conditions in an aquarium and fed blue runner, Caranx crysos, at different ration levels. The relationship between feeding rate and growth rate was best described by a von Bertalanffy growth curve, which predicted a maximum growth rate of 140 kJ kg−1 day−1 (0·66% b.w. day−1), a maintenance ration of 199 kJ kg−1 day−1 (1·06% b.w. day−1), and losses due to starvation of -236kJ kg−1 day−1 (1·11% b.w. day−1). The relationship between gross conversion efficiency (K1) and feeding rate was also examined. K1 ranged from - 64 to 25% and did not drop at high ration levels. Activity levels of both starved sharks and sharks fed at maintenance were not significantly different (0·2 body lengths s−1). K1 values generated from both laboratory and field data suggest that young lemon sharks can convert food to new tissue as efficiently as teleosts.

Gastric evacuation in the young lemon shark, Negaprion brevirostris, under field conditions

Gastric evacuation in young lemon sharks, Negaprion brevirostris, was studied in a field enclosure. Regression analysis was used to evaluate the adequacy of linear, exponential, and square root models in describing the decrease in stomach contents with time after feeding. The linear model produced the best fit and was thus used to compare gastric evacuation at the three temperatures. Gastric evacuation in young lemon sharks is considerably longer than for carnivorous teleosts but shorter than for other elasmobranchs. These differences are the result of differing energy requirements determined by the physiology and behavior of the species.

Relationship between Phytotoxicity of Metabolites Produced in vitro by Strains of Phoma tracheiphila (Petri) Kanc. et Ghik. and Their Virulence

AbstractThree wild isolates and three mutants of Phoma tracheiphila (Petri) Kanc. et Ghilk. were tested for virulence on young Lemon trees. Their respective culture filtrates were tested for toxicity to Tomato cuttings and Sour orange and Lemon leaves. No relationship between phytotoxicity of metabolites produced in vitro and virulence resulted.

Identification and quantitation of adenosine-3?:5?-cyclic monophosphate in plants using gas chromatography-mass spectrometry and high-performance liquid chromatography

Direct evidence has been obtained for the presence of adenosine-3':5'-cyclic monophosphate (cAMP) in tobacco (Nicotiana tabacum L.) callus tissue cultures, bean (Phaseolus vulgaris L.) seedlings and immature kernels of sweet corn (Zea mays L.) through the use of a highly specific and sensitive gas chromatography-mass spectrometric assay. Levels of endogenous cAMP ranged from 70 to 126 pmol/g fresh weight. Corresponding levels of cAMP determined for the same samples using radioimmunoassay were consistently three to four times higher. Contrary to previous reports for citrus plants, measurable levels of cAMP could not be detected in young lemon leaves within the limits of detection of the mass-spectrometric assay method. In the case of tobacco callus tissue, the coumarin glucoside, scopolin, which was present in large amounts and showed similar chromatographic behaviour to cAMP, interferred strongly with the mass-spectrometric measurements of cAMP in inadequately purified extracts. The use of high-performance liquid chromatography, in addition to standard chromatographic purification methods, produced highly purified plant extracts for quantitation of cAMP and also provided a method for the separation of cAMP from its 2':3'-isomer.

Effect of Training Young Lemon Trees for Limb-shaker Mechanical Harvest on Yield and Tree Trunk Growth1

Abstract Three year old lemon trees [C. limon (L.) Burm f.] were selectively pruned to form a 3- to 4-scaffold branch structure for limb shaker harvesting. Yield was reduced 16 kg per tree and trunk circumference 10 cm above the bud union was reduced 5.3 cm per tree over a 6-year period. Training was completed with minimal production loss.

Effect of a Single Application of Napthaleneacetic Acid on Yield and Shoot Growth of Young Lemon Trees1

Abstract Application of 1% ethyl ester of napthaleneacetic acid (NAA) in an aqueous or latex formulation to trunk and scaffold branches of pruned lemon trees [C. limon (L.) Burm.] did not affect yield during the season of application or during the year following application. Regrowth of trunk and limb sprouts was controlled for approximately 1 year.

Ultrastructural observationof lemon fruit abscission

Ultrastructural changes in the abscission zone between ovary wall and floral disc were followed during abscission of young lemon ( Citrus limon (L.) Burm. f. cultivar ‘Villafranca’) fruit explants. Although some cell breakage was observed by light and scanning electron microscopy as well as cell wall dissolution, only middle lamella dissolution was observed by transmission electron microscopy, strongly suggesting that pectic substance dissolution is the primary cause of cell separation. Prior to cell separation the middle lamella of the cell wall stained deeply, the amount of rough endoplasmic reticulum (ER) profiles increased, and the number of Golgi bodies also increased. However no change in mitochondria or chloroplast structure was observed before cell separations, and no microbodies were observed. In Ethephon (2-chloroethylphosphonic acid)-treated explants, essentially similar cytoplasmic and cell wall changes occurred during the course of abscission, but the changes were more rapid.