فصلنامه اکوفیزیولوژی گیاهان زراعی
پیاپی 48 (زمستان 1397)

Drought can have a dramatic effect on plant growth. To evaluate the effect of brassinosteroied on drought stress tolerance of coneflower a split split plot experiement based on randomized complete blook design was conducted in Mahabad. The factors were irrigation regime as the main factor, with three levels (irrigation after 70, 120 and 170 mm evaporation from pan class A), the use of surfactants with two levels (without and with half a liter per hectare) and spraying 24 – Epi- brassinosteroied with three levels (control, 10-8 and 10-7 M). In this study traits like photosynthetic pigments (chlorophyll a, chlorophyll b and total chlorophyll), auxiliary pigments (carotenoids, anthocyanins, flavonoids and phenolic compounds), SPAD index, stomatal conductance, MDA, economic performance (stem, leaf and flower yields), essential oil percent and essential oil yield were measured. The results indicated that interaction of irrigation regime by brassinosteroied application reduced the adverse effects of water stress on chlorophyll a by 28 percent. It was also revealed that the use of brassinosteroied (10-7 M) increased the variation of chlorophyll a by 35 percent and water stress reduced SPAD index by 25%. Use of brassinosteroied (10-7 M) increased SPAD index by 8%. Application of brassinosteroied (10-7 M) increased levels of carotenoids, anthocyanins and flavonoids by 17, 59 and 50 percent, respectively. Use of 10-7 M concentration of brassinosteroied under stress, also interested in stomatal conductance by 13 percent, as compared to that of not its using. The results of prediction function regression showed that stomatal conductance, amount of MDA and chlorophyll a, played significant roles in yield prediction. The results of water stress also, showed a determining role in reducing major growth factors of Echinacea purpurea. But the use of brassinosteroied along with surfactant solution increased its drought tolerance.

To study the effect of water deficit on biochemical changes in chickpea, a split-plot experiment based on complete block design with three replications was carried out at the Research Farm of Razi University in Iran. Moisture regimes with three levels, were: 1) irrigation cut off from beginning of flowering till maturity, 2) irrigation cut off from beginning of podding till maturity and 3) irrigating plants at all stages of growth (control) assigned to the main-plots and five chickpea cultivars: Arman, Azad, Bivanij, Hashem and ILC482 to the sub-plots. Based on the results, two levels of water deficit resulted in significant reduction in the chlorophylls and carotenoids concentration and significant increase in the activity of antioxidant enzymes such as: catalase, peroxidase and super oxide dismutase of leaves, in comparison with control. Therefore, there was a negative correlation between the activity of antioxidant enzymes and the amount of available water in soil, and their activity increased with increasing the severity of water stress. Seed yield was significantly affected by water deficit. In comparison of control treatment, irrigation cut off from the beginning of flowering up to maturity compared to irrigation cut off from podding up to maturity resulted in more reduction in seed yield (36 and 15% respectively). ILC482 cultivar with seed yield of 715 kg.ha-1 under irrigation cut off from the beginning of flowering up to maturity and Arman cultivar with a seed yield of 1355 kg.ha-1 under irrigation cut off from podding up to maturity produced highest grain yield. High yield cultivars under two levels of water deficit including: ILC482, Azad and Bivanij also had the highest photosynthetic pigments concentration and highest antioxidant activity in their leaves. The results also indicated a positive relationship between the antioxidant enzymes activities and photosynthetic pigment concentrations in chickpea which may help to increase growth and yield of chickpea under drought stress conditions.

Guar is a tropical, salt and drought tolerant plant. To assess the effect of salicylic acid on its morphological and agronomical traits under different irrigation intervals, a split plot experiment based on randomized complete block design with four replicates was performed in Galeh-Gang region in Kerman province, Iran. Three different irrigations with 6, 9 and 12 day intervals, assigned to main plots and four salicylic acid concentrations (0, 0.5, 1 and 2 mM) to sub plots. Salicylic acid spraying was done three times at five leaf, flowering and podding stages. The results indicated that most of the morphologic and agronomic characters of guar were influenced under different irrigation intervals. Leaf area index, number of pods per plants and number of seeds per pod were decreased when drought stress occured. Spraying plants with salicylic acid increased almost all characters under study. While, the highest number of pods per plant, seeds per pod were obtained at 2 mM and leaf area index at 1 mM salicylic acid treatments. Irrigation interval by salicylic acid interaction was significant for specific leaf area, 1000 seed weight, seed protein content and seed yield. The highest seed yield (1245.25 kg.ha-1) was belonged to the irrigation of 6 day interval and 1 mM acid salicylic treatment. As a whole it can be concluded that use of 1 mM salicylic acid treatment might increase drought tolerance of guar and prevent yield reduction during drought stress.

To study the effect of different deficit-irrigation methods on yield and water use efficiency of wheat under different water applications a field experiment was carried out in split plot arrangement using randomized complete block design with four replications at the Research Farm of Islamic Azad University, Karaj branch, Iran in 2014-2015 growing year. Deficit irrigation with three levels were I100: use of 100% wheat water requirement, I75: use of 75% wheat water requirement and I50: use of 50% wheat water requirement, which were assigned to the main plots and irrigation methods with three levels, consisting of M1: conventional furrow irrigation, M2: fixed alternate-furrow irrigation and M3: periodic alternate-furrow irrigation which were assigned to the sub plots. The results showed that by using 100% wheat water requirement grain yield in the fixed and periodic alternate-furrow irrigation methods decreased by 21.8 and 23.7 percents as compared to conventional furrow irrigation method, respectively. The highest water use efficiency for grain yield (1.63 kg.m-3) was obtained when 75% wheat water requirement and fixed and alternate-furrow irrigation methods and the lowest water use efficiency for grain yield (1.24 kg.m-3) was obtained when to 50% wheat water requirement, with conventional furrow irrigation method, was used. Also, the highest water use efficiency for biologic yield (4.38 kg.m-3) was obtained at 50% wheat water requirement, with fixed alternate-furrow irrigation method, that decreased 31.5 percent as compared to I100M1. According to the results of this study, the application of alternate furrow irrigation with 75% crop water requirement can be used to increase water use efficiency for wheat yield in the studied area.

Proper crop nutrition is a key factor for achieving suitable crop yield, even under drought stress conditions. To evaluate the effects of soluble potassium sulfate fertilizer and iron chelate on corn (Zea mays L.) seed yield and its yield components under water deficite stress a split split plot experiment based on randomized complete block design with three replications was caried out in Shahryar, Tehran province, in 2014. The main plots were assigned to water deficit stress and normal irrigation and subplots to soluble potassium sulfate and chelated iron. Soluble potassium sulfate levels were 0, 25, 50 kg.ha-1 K2O and iron fertilizer sprayed as Fe-EDDHA. The results showed that interaction of potassium sulfate, iron fertilizer and water deficit stress at seed milky stage was significant (P> 0.05) as to total chlorophyll, plant dry weight, thousand seed weight and corn seed yield. The application of iron, potassium and water deficit stress had also a significant effect (P> 0.01) on biological yield and number of seeds per ear, but their interactions were not significant. Application of 25 kg.ha-1 of potassium sulfate and iron chelate as foliar spray increased seed yield from 5294 kg.ha-1 in control (without fertilizer application) to 6978 kg.ha-1 and seed yield, under water deficit stress at seed milky stage, increased from 3921 kg.ha-1 in control treatment to 4794 kg.ha-1. According to the results of this study, application of 25 kg.ha-1 of potassium sulfate along with the application of iron chelate, at pre-tasseling stage, may produce acceptable yield under water deficit stress condition.

Integrated plant nutrition management is a good method to increase the ‎productivity of crops and improve the environment. To evaluate the ‎effects of using ‎growth promoting bacteria and different levels of vermicompost on quantitative ‎and qualitative yield of rapeseed (Brassica napus L.), a field experiment was ‎conducted in 2014-2015. The treatments consisted of inoculation and non-‎inoculation of canola seeds with growth promoting bacteria and application of ‎different levels of vermicompost (0, 4, 8 and 12 t.ha-1). The results showed that ‎simple effects and interaction of vermicompost and growth ‎promoting bacteria ‎on quantitative and qualitative traits of canola were significant. That is to say ‎with ‎increasing the application of vermicompost from 4 to 12 tons per hectare, a ‎‎significant increase was observed in the traits under study as compared to the control.‎ ‎Inoculation of seeds with growth promoting bacteria also increased the ‎‎amount of measured traits as compared to the control. The application of 12 tons of ‎‎vermicompost per hectare, along with growth promoting bacteria, resulted in an ‎increase in ‎the number of pods per plant, 1000-seed weight, biological yield, ‎grain yield, harvest ‎index and oil yield, (28.63, 4.68 g, 10785.2 kg‎, 3484.2 kg, ‎‎38.02% and 1795.93 kg.ha-1, respectively, as compared with control). Application of ‎‎12 t.ha-1 of vermicompost per hectare along with growth promoting ‎bacteria resulted in grain ‎yield, harvest index and oil yield increase by 83%, 45% and 43%, ‎respectively, ‎as compared with control. Therefore, in soils ‎with low organic matter content, ‎simultaneous application of vermicompost and growth ‎promoters bacteria can ‎improve the quality and quantity of rapeseed yield ‏.‏‎

To investigate the effects of chemical and phosphorus bio-fertilizers on element accumulations, chlorophyll content, seed yield and root growth of three local populations of mung bean, a factorial experiment based on a randomized complete block design with three replications was carried out at the Research Farm of Agricultural Faculty of Ilam University, Ilam, Iran, in 2015. The treatments were three local populations of mung bean (Fereydouni, Arteshi, Gotvandi), chemical fertilizer with three levels: (without using fertilizer (P0), using 75 kg.ha-1 of super phosphate (P75) and 150 kg.ha-1 of super phosphate (P150) and bio-fertilizer with two levels: without using fertilizer (B0) and using 100 g.ha-1 of barvar-2 phosphate (B100). Result showed that application of bio-fertilizer and chemical phosphorus (75 and 150 kg.ha-1 of super phosphate) increased phosphorus, nitrogen, and potassium in seeds and root dry weight of mung bean. Application of bio-fertilizer increased phosphorus and nitrogen contents of three local populations of mung bean. Highest contents of zinc and iron in seed, leaf chlorophyll, number of nodules and root dry weight belonged to Arteshi population. Zinc concentration, chlorophyll and number of nodule in roots increased by using bio-fertilizer. Application of chemical phosphorus (75 and 150 kg.ha-1 super phosphate) increased chlorophyll content of leaves and number of nodule in root of mung bean. Application of both bio-fertilizer and chemical phosphorus increased seed yield of Fereydouni, Arteshi, and Gotvandi by 32.33, 64.87 and 81.35 percents, respectively, as compared to that of control. It can be concluded that reduced application of chemical and phosphorus bio-fertilizers improves the yielding ability of mung bean.

To study the effect of barley-vetch intercropping on their yields and yield components, a two-year field experiment was conducted during 2013 and 2014 growing seasons at the Agricultural and Natural Resources Research Station of Miandoab. Factors consisted of 9 mixed treatments: with densities of 250 vetch plants + 300 barley plants, 250 vetch plants + 500 barley plants, 250 vetch plants + 700 barley plants, 450 vetch plants + 300 barley plants, 450 vetch plants + 500 barley plants, 450 vetch plants + 700 barley plants, 650 vetch plants + 300 barley plants, 650 vetch plants + 500 barley and 650 vetch plants + 700 barley plants per square meter and sole cropping of barley (350 plants per m2) and vetch (250 plants per m2). Experimental design was a randomized complete block with four replications. Result of combine analysis showed that there were significant differences among the patterns of planting treatments. The highest number of spikes per square meter (97.88), thousand kernel weight (47.28 g) and biological yield (7.63 t.ha-1) and seed yield (4.36 t.ha-1) were observed in sole cropping of barley. Also, the highest number of plants (379.25), biological yield (63.67 t.ha-1) and seed yield (1.94 t.ha-1) in vetch were belonged to sole cropping of vetch. In this study the highest land equivalent ratio (LER), based on seed yield (1.20) and biological yield (1.48), belonged to 250 vetch + 500 barley plants treatment, which indicate the usefulness of this intercropping treatment, as compared to the sole cropping of these two plant.

The objective of this study was to evaluate the effects of sowing and picking dates on lint yield and its component, germination and seed vigor of Varamin cultivar of cotton. To this end, experiments were carried out as split-plot in time based on randomized complete block design with three replications at the cotton fields of Kizor in Sabzvar in 2013. Treatments were four sowing dates (May 8, May 20, Jun 2 and Jun 14 of 2013) and two picking dates (the harvest date of first picking for first to fourth planting dates were September23, September29, October 14 and October 27. The harvest dates of second picking for first to fourth planting dates were October 7, October 12, October 24 and November 11). Standard germination and cool germination tests for different temperatures were also performed. 1000-seed weight, number of normal seedlings and dry weight of normal seedlings were measured. Results showed that the effect of planting date, picking and their interaction effects on lint yield, seed thousand weight, number of bolls per plant, single plant weight, number of normal seedlings, dry weight of normal seedlings, germination percent, lint length and electrical conductivity were found to be significant. Highest (3693.3 kg.ha-1) and lowest (1023.00 kg.ha-1) lint yields obtained from the first picking of first planting and second picking of fourth planting, respectively. The number of normal seedlings and dry weight of normal seedlings didn’t follow a special process in standard germination test, but the number of normal seedlings produced from cool germination test of first picking with delay in sowing date was decreased in a linear form. The number of normal seedlings from alternate temperatures (one week in 18°C and the other week in 28°C) “except the first sowing date” was decreased. Results showed that by delaying sowing date (at the range of this study) seed vigor decreased. According to the results of this research, the first planting date (May 8) could be recommeded for growing Varamin cultivar for higher lint yield to this region. But, for seed production, the first picking of second planting date (May 20) is recommended.

To study the effects weed competition periods on fruit yield and yield components of Okra and some of its morphological traits, a completely randomized design experiment with 12 treatment and 13 repetitions was carried out at the Research Fields of College of Agriculture of Birjand Branch, Islamic Azad University, in 2016. The plots consisted of the control (free of weeds until 4, 6, 8, 10 and 12 weeks after okras growth) and the treatments competing with the weeds within the same periods as mentioned above. Also, two separate plots were designed one for complete weed control during whole growth period and in the other weeds were allowed to compete with okra during the growth period, in order to compare the effects of weeds on okra. In the first group the plots were weeded during periods the mentioned above and in the other weeds were let to compete with okra. In the second group weeds competed with okra from the beginning of the growth period to 4, 6, 8, 10 and 12 weeks after germination. There after weed were controlled up to harvest time. The results showed that by increasing competition periods of weeds morphological traits of okra like plant height, main stem branche numbers, fresh fruit length and its diameter, as well as the number of fresh fruits per m-2, fresh fruit and dried fruit yields, biological yield and dried fruit harvest index per plant, dry weight of broad and narrow leaved weeds, and the percentage of dry fruit yield as compared to that of control treatment were significantly decreased. Based on 5 and 10 percent reduction in fruit yield, starting days of critical weed control period was determined to be 29 and 30 days after seed germination. Thus, it can be concluded that the critical weed period, in terms of okra yield in regard with the mentioned levels, was estimate to be 77 and 80 days after seedling emergence. Therefore, it is recommended that from the 29th to 80th day after seedling emergence of the okra, the field ought to be free of weed.