جستجوی مقالات مرتبط با کلیدواژه « Water deficit » در نشریات گروه « منابع طبیعی »

The aim of this study was to investigate the response of anise to the occurrence of drought stress in different stages of growth of this plant and also the effect of humic acid in reducing the negative effects of drought stress and improving plant growth characteristics in climatic conditions of Quchan city. For this purpose, an experiment was conducted in the form of split plots based on randomized complete block design with three replications in the 2019-2020 cropping year. The irrigation treatment in four levels was as the main factor of the experiment and consumption of Humic acid was considered as sub-factor in three levels. According to the obtained results, stopping irrigation at the seeding stage and nonuse of humic acid in comparison with full irrigation and consumption of 4 kg of humic acid reduced the 1000-seed weight of anise by 23.45%. Also, cessation of irrigation at the stages of stemming, flowering and seeding reduced the grain yields by 7.80, 29.46 and 24.08%, respectively, compared to the control. The use of humic acid at both levels of 2 and 4 kg/ha increased grain yields by 5.01 and 10.64%, respectively, compared to the control. According to the results obtained in this study, despite the problem of water shortage in the study area, one solution to solve this problem is to stop irrigation in the pre-shoot stage, which can reduce water consumption in the production of anise. Also, the application of humic acid at the rate of 4 kg/ha will significantly compensate for the negative effects of drought stress during vegetative and reproductive growth stages.

This study was conducted to investigate the effect of mulch application from organic matter residues in forest area, rice fields, tea and peanut orchards and irrigation water deficit on different morpho-physiological and biochemical characteristics of forage sorghum in field conditions. This research was carried out as a factorial experiment in a randomized complete block design with three replications in selected research farms in Deilman area of Siahkal city under the supervision of Tarbiat Modares University, Department of Agronomy and Lahijan Agricultural Jihad Extension Experts in 2018. Factorial combinations of three levels of water deficit stress 15%, 30% and 45% of less than FC and six organic mulch, no mulch, rice straw mulch, paddy rice husk mulch, peanut shell mulch, tea waste mulch and leaf mold mulch were used. The results showed that under moderate stress conditions, rice straw mulch and rice paddy husk treatment showed the highest forage yield and plant photosynthesis rate of 39.13 and 26.65%, respectively, compared to the control treatment. Also, under conditions of severe stress, rice straw mulch, rice paddy husk and peanut shell mulch increased the economic efficiency of water and dry weight of weeds by 63.48, 55.21 and 46.40%, respectively, compared to the control. Application of organic matter mulch, especially rice straw, rice paddy husk and peanut shell mulch, prevented a reduction of 6.08, 13.70 and 16.75% of grain yield compared to the control under moderate stress conditions, respectively. In general, organic matter mulch has a high ability to increase grain and forage yield, photosynthetic rate, antioxidant activity and economic efficiency of water, as well as reduce field weeds in stress conditions and make a significant contribution to improving drought resistance in Forage Sorghum. Finally, the use of organic matter mulch in the cultivation of forage sorghum under seasonal drought stress conditions is recommended.

Because of the importance of the role of maternal environment during seed development on germination of produced seed and seedling establishment an experiment in a randomized complete block design base as a factorial was conducted to evaluate effects of drought stress (0.0, -0.2, -0.4, -0.8 and -1 MPa) on germination and seedling growth characteristics of wild oat seed production under different irrigation regime (100,80 and 60 percentage of water requirement of wheat from stem elongation stage to the end of growth season) in Shahrood Agriculture research center. According to the results, maternal irrigation regime, drought stress and interaction effects between them had significant effect on germination and seedling characteristics of wild oat. The results showed that germination characteristics were decreased significantly with decrease of water potential to -1 MPa. The highest rate and percentage of germination and radicle length in this water potential was related to irrigation regime of 60% water requirement and the least of plumule dry weight was related to irrigation regime of 60 and 80% water requirement. Length and dry weight of plumule decreased more than those of radicle under drought stress conditions and showed greater sensitivity to reduced water potential. Lower dry weight and green area was observed in seedling that germinated at water potential more than -0.4 MPa. The results showed that drought stress during the seed formation caused significant changes in response of wild oat germination under stress condition.

In order to evaluate the seed and essential oil yield and harvest index of cumin, a factorial experiment based on randomized complete blocks design was conducted with three replications, at the research farm of the faculty of agriculture of Urmia University in 2010. Treatments were four irrigation regimes (irrigation after 50, 100, 150 and 200 mm of evaporation from a class A pan) and different amounts of superabsorbent polymer (0, 60, 120, 180, 240 and 300 kg/ha). The highest biomass yield (3640 kg/ha), seed yield (1226 kg/ha) and essential oil (36.5 kg/ha) belonged to irrigation after 50 mm of evaporation and 60 kg/ha superabsorbent polymer application. Increasing in irrigation distances to 100, 150 and 200 mm of evaporation needs to 180 and 120 kg/ha polymer to produce maximum yield (biomass and seed), but they were 60 and 300 kg/ha polymer for essential oil yield and harvest index, respectively. The maximum harvest index of seed for irrigation after 100, 150 and 200 mm of evaporation belonged to 180 kg/ha superabsorbent treatment. Application of superabsorbent at irrigation after 50 mm of evaporation (non-stress condition) does not have efficiency for essential oil production compared with the control (without polymer in this irrigation). In conclusion, increasing irrigation intervals from 50 to 200 mm of evaporation from pan lead to reduce the yield (biomass, seed and essential oil), that application of superabsorbent polymer A200 compensate part of this reduction.