Journal of Plant Physiology and Breeding
Volume:10 Issue: 1, Winter-Spring 2020

The growth and development of tomato seedlings (Solanum lycopersicum L.) are drastically inhibited under water stress. Putrescine (PUT) is involved in water stress tolerance. However, very limited information is known concerning the effects of exogenous application of PUT on plants including tomato. This experiment was carried out to study the application of putrescine on some physiological and biochemical factors of tomato under the water stress. Plants were exposed to three water conditions: 100 % (ET0) as well- watered treatment (or control), 75 and 50% of ET0 as a water stress treatments. Foliar applications of PUT were applied at 0.5 and 1 mgL-1 while control plants were sprayed with distilled water. Drought stress significantly impaired the plant growth and productivity, and reduced leaf area, plant height, fruit yield at 50% ET0 compared to control treatment. Also antioxidant enzymes such as SOD, PPO, and CAT were increased by increasing the water stress conditions. The application of PUT improved the growth characters, plant height, fruit yield, and leaf area under water stress. Furthermore, PPO content and CAT and SOD enzyme activities were also improved by applying PUT. The results of this study indicated that foliar application of putrescine in proper level may act as elicitor to trigger physiological processes and induce valuable metabolites biosynthesis, which may compensate the negative impacts of drought stress on plant biomass, quality and quantity.

The present study aims at evaluating the decreased percentage seed yield and its components in sweet corn under drought stress combined with foliar ascorbic acid during the cultivation season on May 26th, 2016. An experiment as a split plot based on randomized complete block design with three at the Agricultural Research Station of Ardabil was carried out. The main plots were four levels of drought stress (a1: irrigation after 70 as control, a2: 100, a3: 130 and a4: 160 mm evaporation from pan class A), and the sub-plots were four levels of foliar ascorbic acid (b1: control, b2:150, b3: 200 and b4: 250 ppm). The results of the study revealed that drought stress significantly decreased the length of ear, number of grains per ear, number of grains row per ear, number of grain in row, dry weights of covers ear, 300 seed weight and grain yield. The foliar application of ascorbic acid had positive effects on decreasing drought stress on all traits in this study. In general, the results indicate that the usage of ascorbic acid decreased the harmful effects of drought stress and significantly increased tolerance to drought stress in traits of corn plant.

In order to study the effects of methanol on some physiological and biochemical characteristics of pot marigold (Calendula officinalis L.) under drought stress, a factorial experiment was conducted based on randomized complete block design with three replications under greenhouse condition in 2017. Treatments were included foliar application of methanol at four levels [control at 0 (M1), 20% (M2), 30% (M3), and 40% (M4)] and four irrigation treatments [irrigation at 40 (I1), 60 (I2), 80 (I3) and 100% (I4) of field capacity]. Increasing water deficit, significantly reduced chlorophyll a, chlorophyll b, total chlorophyll, carotenoid, Fv/Fm and stomata conductance, whereas 20 and 30% methanol application significantly improved these traits. Irrespective of 40% methanol application, the moderate and severe water deficit treatments lead to decrease of chlorophyll a, total chlorophyll, carotenoid and Fv/Fm. In addition, water deficit showed a significant increased on soluble sugars content, proline accumulation and CAT, POD and PPO activity. Compared with the non-methanol treatment, application of methanol increased above mentioned parameters. The maximum values of these variables were obtained with the application of 40% methanol under severe water limitation condition. It was suggested that the improvement of plant biomass due to methanol spraying was associated with the increase of antioxidant defense abilities and maintaining many physiological processes of stressed plants.

Tuberose is an important cut flower in Iran and throughout the world. Since nutrition is of crucial significance for the growth, development, and quality of ornamental plants, the present study aimed to explore the effect of different levels of humic and folic acids on yield and quantitative and qualitative traits of tuberose (Polianthes tuberosa L.) based on a randomized complete block design with three replications in the Faculty of Agriculture, Agriculture and Natural Resources University of Gorgan, Iran in 2016. Humic and folic acids were applied at the rates of 0, 50, 100 or 150 mg L-1. The foliar application was performed in three phases, i.e. 30, 50 and 70 days after planting. The recorded traits included spike length, stem length and diameter, shoot fresh weight, floret number, leaf number and area, flower emergence time, bulblet number, root development depth, N, P and K content, vase life, and total chlorophyll. Analysis of variance showed that the application of humic acid significantly influenced all measured traits, except leaf number and flower emergence time. As humic acid rate was increased to 150 mg L-1, leaf total chlorophyll content was increased by 52 percent showing a significant difference with control. The foliar application of humic and folic acids increased N, P and K contents of leaves, and the strongest effect was observed at the rate of 150 mg L-1. The results lead us to the conclusion that the application of 150 mg L-1 humic acid and folic acid had the strongest impact on increasing the quantitative and qualitative traits of tuberose.

Optimization of medium components because of being multifactors is very difficult. In order to optimize the plant growth regulators (BA, IBA and GA3) for shoot proliferation of apple cv. ‘Abbasi’ a three-factors experiment was designed and performed in 20 points using Design Expert software according response surface method. A completely randomized design (CRD), based on eigth auxin combinations (IBA+NAA), also were performed for in vitro rooting of microcuttings. Proliferated shoot number was linearly and positively affected by the BA factor, while the response to the leaf number was linearly and negatively affected by BA. The effect of GA3 on proliferated shoot length response was observed in negatively linear model. The abnormal shoot percentage in a quadratic model was influenced by all three factors, BA, IBA and GA3; positively linear by BA, positively quadratic by IBA, and negatively quadratic by GA3. According to the results of this experiment, the optimum concentrations for BA, IBA and GA3 were 1.5, 0.1 and 0.02 mg L-1, respectively, which resulted proliferate shoots with a rate of 2.5 shoots per explant, with 0.9 centimeters in length, 4.3 leaves per shoot, and 4% of abnormal shoots. The percentage of shoot-tip necrosis was not affected by the evaluated factors. NAA was more effective than IBA for rooting of microcutings, and medium aupplelment with 1 mg L-1 IBA or 0.5 mg L-1 NAA can be used successfully for rooting of apple cv. ʽAbbasiʼ shoots in vitro.

Strawberry cultivation requires the use of cultivars adapted to the field or greenhouse conditions of the production region. Seven commercial of short day (SD) and day neutral (DN) strawberry cultivars (Camarosa, Kurdistan, Mrak, Paros, Queen Elisa, Selva, Ventana) were compared as a completely randomized design for different morpho-physiological characters under greenhouse conditions. The cultivars showed variation for all of the studied traits. Days to flowering varied from 53.2 to 94.5 days among the cultivars and Paros followed by Camarosa required minimum days for flowering. The highest total chlorophyll content and fruit volume were obtained in Camarosa and Paros, while the highest fruit weight was found in Paros, Ventana, Camarosa and Kurdistan. The cultivar Camarosa produced the highest of flower number (42.0), fruit number (36.3), fruit firmness (4.8 N) and yield (424.7 g per plant). The TSS/TA ratio was observed maximum in Paros and minimum in Ventana and Mrak. The highest of fruit anthocyanin was recorded in Camarosa and Selva. Correlation analysis revealed that yield per plant had a positive correlation with total chlorophyll content of leaves, number of flower and fruit, weight and volume of fruit, while negatively correlated to leaf area and crown number. According to stepwise multiple regression analysis, yield had the highest relationship with the number of flowers and fruit weight, respectively. Generally, vegetative traits as well as days to flowering and fruiting were higher in DN cultivars (Mrak, Selva). However, SD cultivars produced higher flower number, fruit size and yield than DN cultivars. The cultivars Camarosa and Paros were most adapted to the greenhouse conditions among the experimental cultivars.

This research was carried out using seven generations of MO17 (the paternal line), B73 (the maternal line), F1 (SC704), F2, F3,BC1 and BC2 to study the inheritance of chlorophyll fluorescence parameters and relative water content using generation mean analysis. The experiment was conducted in the research station of the University of Tabriz, Iran, with two replications for each generation under normal irrigation and two water deficit conditions. The existence of epistatic gene interaction was observed in controlling of F0, Fm, FV (in the severe stress condition),FV/Fm (in the normal condition), FV/F0 (in the normal and severe stress conditions) and RWC (in the normal and moderate and severe stress conditions). Duplicate epistasis was observed for all studied traits under the normal and water deficit conditions except RWC in the severe stress condition. Therefore, exploiting non-additive gene action and delaying the selection to advanced generations for physiological traits in maize was suggested to adopt in the programs aimed at developing drought-tolerant lines and hybrids.

Five varieties of Phalaenopsis (Nottingham, Dubrovnik, Andorra, Memphis, Bucharest) were self-pollinated and crossed with each either as the male or the female parents. The five self-pollination and 20 cross-pollination states were evaluated for six phenological and morphological characteristics. Pollination was performed using an orchid pollination syringe in a greenhouse with a temperature of 20-27 ◦C, the humidity of 80% and light of 2500 lx during the 2018-2019 growing season. Nottingham under self-pollination conditions was better than other varieties and was superior to all crosses for all traits under investigation. The differences among males, females and their crosses were significant for all traits, except the time to the first pollination signs in which the effect of the female factor was not significant. In general, Nottingham was the superior variety in almost all traits and Dubrovnik was the worst variety in most traits either as male or female parents. Cross-pollination also had different outcomes in different traits. For example, for the time until swelling of the capsule, crosses Memphis × Nottingham and Nottingham × Memphis caused the capsule to fill later than the Nottingham parent. The cross Dubrovnik × Nottingham caused the capsule to fill earlier than the Dubrovnik parent. In the Dubrovnik × Nottingham cross, the weight of seeds per capsule, as an important trait, was higher than the Dubrovnik parent under self-fertilization conditions. Also, the cross-pollination was not suitable for increasing the weight of seeds per capsule in the Nottingham × Andorra cross. As an example for the capsule length, the Nottingham × Bucharest cross had smaller capsules than the self-pollination conditions of Nottingham and Bucharest. Therefore, depending on the importance of the traits under consideration in commercial production, cross-pollination can be used as a method, in addition to producing flowers with colors and shapes different from the parents, for improving the desired traits relative to one parent or both parents in self-pollination conditions.