Improving oil and flavonoid contents of milk thistle under water stress by salicylic acid

Adverse environmental conditions such as water deficit can limit production. However, some of these adverse effects may be overcome by application of plant growth regulators including salicylic acid (SA). Thus, a field experiment was conducted in 2015 to evaluate the effects of SA (0 and 1 mM l-1) on yield components, seed yield and oil and flavonoid contents of milk thistle (Silybum marianum L.) under different irrigation treatments (I1, I2, I3 and I4: irrigation after 70, 110, 150 and 190 mm evaporation from class A pan, respectively). The experiment was arranged as split-plot based on randomized complete block (RCB) design in three replicates. Irrigation treatments and SA levels were located in the main and sub plots, respectively. The results indicated that plant biomass, seeds per plant, 1000 seed weight, seed yield per unit area and harvest index of milk thistle decreased as a consequence of water stress. Oil percentage and yield were also reduced, but flavonoid content enhanced with increasing water deficit. All these traits were considerably augmented by foliar application of SA under non-stress and stressful conditions. Therefore, it was conclude that SA can be used to improve field performance of milk thistle under different environmental conditions

Effect of Salinity Stress on Seed Quality of Chickpea

A factorial experiment on the basis of RCB design with three replications was conducted in 2007, to investigate the effects of salinity stress (S1, S2 and S3: control, 5 dS/m and 10 dS/m, respectively) on seed quality of three chickpea cultivars (ILC and Jam from kabuli type and Pirooz from desi type) at different stages of development (H1, H2, H3 and H4: 38, 46, 54 and 69 days after flowering). Seed weight, germination percentage and germination rate were significantly affected by salinity and harvest time, but cultivar had only significant effect on seed weight and germination percentage. Comparison of means indicated that 100 seed weight and percentage of germination for ILC and Jam cultivars were statistically similar, but these traits for Pirooz were significantly less than those for two other cultivars. Seeds produced under non-saline conditions (S1) were larger than those produced under low (S2) and high (S3) salinities. Moreover, germination rate and percentage of all seeds decreased, as salinity increased. Seed weight of chickpea increased with progressing seed development. In general, the rate and percentage of germination for all cultivars increased with increasing seed weight. Thus, salinity stress and immaturity can reduce the quality of chickpea seeds

Can application of nitrogen fertilizers and salicylic acid improve growth and fruit yield of coriander under water deficit?

To investigate the changes in selected morphological traits and yield of coriander (Coriandrum sati- vum L.) in response to fertilization and salicylic acid foliar spraying under different irrigation intervals, two field experiments were conducted as split-factorial based on randomized complete block design with three replicates in 2014 and 2015. Treatments were three irrigation intervals (irrigation after 60, 90 and 120 mm evaporation from class A pan) and combination of fertilization (control, urea 100 kg ha–1, Nitrokara (bio-fertilizer), and 50% urea + Nitrokara) and salicylic acid (0 and 1 mM) that were allocated to the main and sub-plots, respectively. The results showed that plant height, length of the longest internode, stem diameter, branches per plant, dry weights of roots and leaves and fruit yield of coriander were reduced and root length enhanced with increasing the irrigation intervals. However, all of the nitrogen fertilizers, especially combined application of 50% urea and Nitrokara, and salicylic acid spraying, improved the selected morphological traits, and consequently fruit yield per unit area under favorable and limited irrigations

Effect of Water Deficit on Morphological Traits and Water Use Efficiency of Two Soybean (Glycine max L.) Cultivars

In order to investigate the effect of water limitation on morphological traits and water use efficiency in two soybean cultivars, a split-plot experiment was conducted in 2004 at the Research Farm of the Faculty of Agriculture, University of Tabriz, Iran. Irrigation treatments ( I1, I2, I3 and I4: irrigation after 60±3, 80±3, 100±3 and 120±3 mm evaporation from class A pan, respectively) were assigned to main plots, and two soybean cultivars (Zane and Huck) were allocated to the subplots. The results indicated that the Huck required less GDD (growing-degree days) to complete the growth and developmental stages, compared with Zane. Flowering and maturity for Huck occurred about 3 days earlier than those for Zane. The mean number of branches, plant height, biological and grain yields under well watering (I1) were higher than those under limited irrigations (I2, I3 and I4). All these traits were decreased with increasing water deficit. The highest harvest index was obtained from I1 treatment, however, this superiority was not significant statistically, when compared with other irrigation treatments. Therefore, it was concluded that water use efficiency (WUE) could be improved, with decreasing irrigation. However, the volume of water at each irrigation increased and grain yield decreased, as water deficit severed. Consequently, it seems that irrigation with low volume and short intervals might be more suitable for soybean production

Water stress and insect herbivory interactively reduce crop yield while the insect pollination benefit is conserved

Climate change is predicted to hamper crop production due to precipitation deficits and warmer temperatures inducing both water stress and increasing herbivory due to more abundant insect pests. Consequently, crop yields will be impacted simultaneously by abiotic and biotic stressors. Extensive yield losses due to such climate change stressors might, however, be mitigated by ecosystem services such as insect pollination. We examined the single and combined effects of water stress, insect herbivory and insect pollination on faba bean yield components and above- and belowground plant biomass under realistic field conditions. We used rainout shelters to simulate a scenario in line with climate change projections, with adequate water supply at sowing followed by a long period without precipitation. This induced a gradually increasing water stress, culminating around crop flowering and yield formation. We found that gradually increasing water stress combined with insect herbivory by aphids interactively shaped yield in faba beans. Individually, aphid herbivory reduced yield by 79% and water stress reduced yield by 52%. However, the combined effect of water stress and aphid herbivory reduced yield less (84%) than the sum of the individual stressor effects. In contrast, insect pollination increased yield by 68% independently of water availability and insect herbivory. Our results suggest that yield losses can be greatly reduced when both water stress and insect herbivory are reduced simultaneously. In contrast, reducing only one stressor has negligible benefits on yield as long as the crop is suffering from the other stressor. We call for further exploration of interactions among ecosystem services and biotic and abiotic stressors that simulate realistic conditions under climate change