The effects of wastewater reuse on potato growth properties under greenhouse lysimeteric condition

In this study, raw and treated wastewaters were reused for potato cultivation in order to verify the effect of wastewater on crop yield, crop’s heavy metals’ concentration as well as some major traits of potato. To this regard, a completely randomized test was designed with five water treatments and three replications. The watering were as follows: raw wastewater (T1), treated wastewater (T2), a combination of 50 % raw wastewater and 50 % fresh water (T3), a combination of 50 % treated wastewater and 50 % fresh water (T4), and fresh water (T5). The experiments were run during October 2009–June 2010 in the greenhouse of Bu-Ali Sina University. The results show that the effects of treatments were significant on the length and number of stems per plant (p < 0.05). The number of nodes and weight of tubers, crop yield and heavy metal (cadmium, nickel and lead) concentration in shoots and tubers were also significant (p < 0.01). The results indicated that the highest length of stem (55.44 cm) was obtained in T2 which had no significant differences from that of T1. The maximum and minimum tuber weights and crop yield were obtained in T1 and T5, respectively. Based on crop yield rate, the watering ranked as follows: T1 > T3 > T2 > T4 > T5. The maximum and minimum heavy metal values were observed in T1 and T5, respectively. Based on the cadmium, nickel and lead accumulations in shoots and tubers (except cadmium in shoots), the watering treatments ranked as: T1 > T3 > T2 > T4 > T5

SPATIO‐TEMPORAL VARIATIONS OF SEVEN WEATHER VARIABLES IN IRAN: APPLICATION OF CRU TS AND GPCC DATA SETS †

Iran's climate-sensitive agriculture and water resources are vulnerable to climate change and investigation of climatic trends helps in preparing adaptation strategies. Weather stations are sparsely distributed and access to complete weather data is limited. In such situations, gridded global/regional data sets are promising alternatives. Here, monthly time series of seven weather variables (i.e. monthly averages or monthly totals of daily values) were obtained from the Climatic Research Unit TS V4.01 and Global Precipitation Climatology Centre V7 gridded data sets in 675 grid cells covering the country and analysed over the periods 1957–1986 and 1987–2016 at annual, seasonal and monthly scales. Over the two periods and at a national scale, mean temperature has increased by 0.004 (P = 0.717) and 0.04 °C yr−1 (P = 0.000), while the diurnal temperature range has not significantly changed (P > 0.6). Annual total precipitation experienced an insignificant increase (0.81 mm yr−1; P = 0.666) over the first period but declined by 2.12 mm yr−1 (P = 0.041) over the second. Potential evapotranspiration (PET) has increased by 0.32 (P = 0.398) and 1.43 mm yr−1 (P = 0.015), respectively. Since 1987, significant increasing trends in temperature were detected all over the country. While significant increasing trends in annual precipitation were detected in the central regions and south-west over the first period, decreasing trends prevailed during 1987–2016 in the south, southwest and east with winter being the largest contributor to annual trends. Over the last three decades, annual PET has increased mostly in the north-west and south-east while significant increasing trends were detected in 89% of grid cells, except in a few cells in the north-east. Cloud cover, vapour pressure and frequency of frost days were also analysed. These results are crucial for policy-makers, researchers and engineers in the country and internationally who usually base their decisions and designs on outdated data sparsely distributed in space