نشریه یافته های نوین کشاورزی
سال پنجم شماره 2 (پیاپی 18، زمستان 1389)

The effect of source restriction on yield and physiological indexes of corn was studied in Varamin، Iran، during 2007-2008 and 2008-2009 growing seasons. The experiment was carried out in a complete randomized block design with split plot arrangement. The irrigation regimes were allotted to main plots. The intensity and time of defoliation combination were allotted to sub plots. In moderate irrigation plots، the irrigation was done when the soil water content reached to 75% of available water content. In under stress plots، two short periods of water-holding were applied at V8 and tasseling growth stages. Defoliation treatments were consisted of: Control، cutting 1:3 of leaves at V8، cutting of 2:3 of leaves at V8، Cutting 1:3 of leaves at tasseling and cutting 2:3 of leaves at tasseling. This result showed that remobilization efficiency of stem reserves for grain yield is mostly related to sink capacity than source strength. Under moderate irrigation، later or more intensity defoliation decreased the RGR. While under drought stress، cutting the 2/3 of leaves did not decrease the relative growth rate. The improved NAR due to defoliation caused to compensate the decreased leaf area. So، late and more intensity defoliation could not decrease the CGR. The grain yield of 8. 9 t ha-1 was attained by moderate irrigation which was a results of 16. 4% and 27. 3% greater biomass and harvest index compared to the water stress conditions. This indicates that pot-anthesis water deficiency decreased the sink capacity more than source strength. The results showed that under water deficiency and source strength restriction، the stem reserves play an important role in grains filling process. But under high soil water supply، these reserves will be needed when the source strength is limited after flowering stage. Under moderate irrigation، there were not significant differences among defoliation treatment for remobilization efficiency of reserves from stem to grains.

In order to investigation of zeolite and potassium effect on sugar beet yield and its vegetation growth an experimental design was done based on RCBD with three replications. Research was done in a farm 5 km far from Arak along to the Farahan road in 2007. Traits were selected as zeolite (500 kg/ha)، zeolite+potassium (200 and 50 kg/ha respectively) and no zeolit and potassium as control. Planting process was done in 14th of April in row crop method with 50 cm distance between rows and 25 cm within seeds. Leaf area index (LAI)، the dry and wet basis weight of branches، branches moisture content، root yield، biomass and root length were measured as main characteristics before and after of harvesting. Results showed that there were significant effects on traits about LAI، dry and wet basis weight of branches and biomass but no significant difference between zeolite and zeolite+potassium traits.

In order to evaluate of sowing date on phonology and panicle development of rice cultivars in direct seeding condition. Four seeding date as 30th of April and 10، 20، 30th of May and three cultivars as Hashemi، Tarom and Elpaso were arranged in a split plot design as based on RCBD in 2007 with four replications. The results indicated that seeding date had significant effect on traits of productivity effort، days to panicle emergence، days to 50% panicle initiation، grain filling period، panicle weight and total plant dry weight. The second sowing date with a 25. 17 had the highest grain filling duration and had the highest operation in the amount of 5029 Kg/ha. All traits had affected by cultivar treatment. Tarom cultivar had the most seed filling duration (25. 88 days) and highest yield in the amount of 4444 Kg/ha. Cultivars and planting date interaction was significant in days to ear emergence، days to 50% panicle initiation، panicle weight، total plant dry weight and productivity effort. Elpaso cv had the highest days to panicle emergence (93. 75 days)، days to 50% panicle initiation (101 days) in the first planting date. It produced the highest panicle weight (681 g. m-2) and total dry matter (1139 g. m-2) in the second planting date and it was superior in productivity effort (0. 63) than others. Tarom cv had the highest grain filling duration (27. 50 days). Elpaso cv had the highest assimilate partitioning، because it had the highest productivity effort and grain filling rate. Because the sowing dates was considered based on temperature and time of harvest، the best sowing date، the second sowing date and best cultivar، cultivar Elpaso suggested. Because it have allocated the highest yield.

In order to study the effects of vermicompost and amino acids application on flower yield of Chamomile (Matricaria chamomilla L.)، an experiment was carried out in the Alborz Medicinal Plant Research Station at Karaj region. The experiment design was factorial based on RCBD with three replications. Treatments were vermicompost in 5 levels (0، 5، 10، 15 and 20 ton/ha) and amino acid spraying in 3 levels (at budding stag، at flowering stage، at budding stag + at flowering stage). Results of this investigation showed that days to budding and flowering are not affected by amino acid spraying. But، vermicompost had significant effect on days to flowering. The highest plant height (41. 8 cm)، fresh flower yield (3335. 7 kg/ha) and dried flower yield (653. 8 kg/ha) were obtained by using 20 tons vermicompost per hectare. Maximum yield were obtained by amino acid spraying in 2 times (at budding stag + at flowering stage). According to the interaction effects of the treatments، applying of 15 ton/ha vermicompost and spraying amino acids in 2 times (at budding stag + at flowering stage) caused highest fresh and dried flower yield.

In order to evaluate different levels of irrigation on yield of potato varieties, experimental was done in Tabriz region during 2009. The experiment was arranged as split-plot based on RCBD with three replications. Treatment was different levels of water stress (irrigation after 70, 110 and 150 mm evaporation pan evaporation class A) and five potato cultivars (Agria, Satyna, Savalan, Kaiser and Markis).The results showed that different levels of water in height, number of stems, number of tubers larger than 60 mm, shoots and tuber dry weight, nitrate content in tubers and yield was significant at 1% level. And at 5% level significant were obtained for a percentage of dry matter of tubers. Varieties in height, number of tubers larger than 60 mm, shoot dry weight and yield at 1% and tuber dry weight at 5% level was significant. Also, interactions were significant in height, shoot number and yield at 1% and tuber dry weight 5% level. The highest plant height equivalent was 83 cm by irrigation after 70 mm evaporation from pan evaporation surface was irrigated with 150 mm of water evaporated from the pan surface and the lowest shoot length equal to 49.39% decrease in same Figure has been obtained. Maximum number stem was equivalent 5.497 in cultivar Agria by the control and lowest number stem was 2 numbers in Markis in the control that can be caused by genetic differences. Maximum yield was equivalent 3.598 kg/m2 in Agria by level control and least amount of yield reduction in this equivalent 46.11% by irrigation after 150 mm evaporation from pan evaporation levels are achieved. The purpose of this experimental was the resistance of different varieties of potatoes to different levels on growth and performance.

To determine the effect of water deficiency in different stage of two wheat cultivars; Chamran and Kavir، accompany with application of various elements such as potassium (K)، zinc (Zn) and copper (Cu) on quantity and quality of yield. Two years field experiments was carried out as Completely Randomize Block under spilt - spilt plot design with three replicates، on loamy fine sand soil during 2001 until 2003 growth season at the Research Center Institute of Zabol which is located in the Eastern of Iran. In these experiments، treatments of irrigation involved; well -irrigation، stop - irrigation after pollination (1 - 10. 5، Fix scale) and stop- irrigation after milky stage of grain (5 -10. 5، Fix scale)، and fertilizer treatments included; nil fertilizer، copper sulphate (Cu So4) and zinc sulphate (ZnSo4)، potassium sulphate (K2 So4) as 0، 30، 40 and 150 kg per hater، respectively. All fertilizer is applied at sowing time as sub- plots. The results of this study highlight that the stopped- irrigation at pollination stage reduced significantly biological yield، grain yield production and harvest index. However، in this case Chamran produced high biological yield and grain yield than Kaiver. In addition، application of fertilizer has significant effect on grain yield. In this experiment، stopped-irrigation treatments had significant effect on، nitrogen (N) concentration of grain. Also، K، Zn، and Cu increased high concentration of N in grain، and Chamran varity accumulated high N in grain than Kaiver.

The present research was conducted in order to investigate and compare the yield and yield components of hybrid cultivars of sweet corn in different sowing dates as split plot with 4 replications in complete random blocks at Islamic Azad University، Arak branch، in 2008. The treatments include date of sowing as main factor (09 June 2008، 20 June 2008 and 01 July 2008) and the cultivar as the subsidiary factor (Merit، Chase، Ksc. 404، Ksc. 403). The results indicate that sowing date has affected on grain yield، plant height، grain number in row، 1000 grain seeds and biologic yield; and the differences were statistically significant. The studies reveal that the effect of sowing date and cultivar on number of rows in was not statistically significant and it was not affected by sowing date and cultivar. In addition، among the studied cultivars، the cultivar Ksc. 404 showed more privileges compared to the other studied cultivars such that in the matters of height، grain yield، grain number in row، 1000 grain weight and the biologic yield، the highest specifications were attributed to it and grain yield in maize harvested in the stage equivalent cultivar KSC. 404 by 4. 76 t/h and 1000 grain weight by 190. 8 gr compared to the other were higher than other cultivars which has been studied. The results of this experience show that the date of sowing on 09 June، 2008 and the cultivar Ksc. 404 were the most suitable sowing date and cultivar، respectively، according to this region''s climate.

Soybean development Reproductive stage were predicted by climatic parameters as daylength and temperature. Therefore، fifteen soybean lines and cultivars as name as Williams، Zane، M4، M12، S. R. F، Miandoab، A3935، A3237، L17، Union، Grangelb، Clark، Tns95، Elf، Calland were studied in four planting dates. Soybean genotipes were used in a RCBD in each planting dates. Daylength and temperature effect were evaluated by planting dates levels. Flowering occurance and development Reproductive stage duration were fitted growth degree days، photoperiod and photothermal units in a Multiple Regression Method. The results indicated that photoperiod had significant effect on Maturity in all of lines and cultivars. But photothermal had positive significant effect in Williams. Therefore It caused to delay in Maturity if It was increased. Photothermal was calculated from growth degree days by photoperiod in each days. But the photoperiod was more effective than gdd in time of Maturity. Growth degree days affected on time of Maturity by photothermal and caused to promote it. Reproductive development duration of Elf was affected by gdd.

This experiment was done to evaluate the effects of organic manure and nitrogenous fertilizers on some yield components of sunflower (Helianthus annus) as host plant and growing factors of broomrape (Orobanche aegyptiaca). The experiment was arranged as factorial experiments in randomized complete blocks design with three replications in Shahriar، Iran. First factor was conducted in three levels consisting of: control، cow manure (10% of each pot) and jift (10% of each pot). Second factor carried out in six levels consisting of: control، ammonium sulphate، ammonium phosphate، potassium nitrate، urea، ammonium nitrate. For all kinds of nitrogenous fertilizers (except control) level of pure nitrogen was 3ppm. The results showed that organic soil amendment had a significant effect on yield components of sunflower and the stem number and dry weight of broomrape. Cow manure decreased the dry weight of broomrape and increased dry weight of stem and capitol and seed of sunflower. Jift had decreased stem number and dry weight of broomrape and decreased the dry weight of stem and capitol and seeds of sunflower. Urea decreased the height and fresh weight of broomrape in comparison with other kinds of fertilizers.

In order to determine the best transplanting date for the flue-cured tobacco (cv. K326) in rain fed conditions، this study was done in randomized complete block design with 7 transplanting dates every 10 days (4، 14 and 24 April، 4، 14 and 24 May and 3 June) in 4 replications in Tirtash Research and Education Center in 2009. The results showed the significant effect of transplanting date on all studied factors except the number of leaves، the percentage of sugar and nicotine. Days from transplanting to flowering were the lowest for April 4th (90. 3 days). Maximum dry weight of leaves (3824 kg/ha) was obtained for transplanting date May 4th that shows about 36% increase compared to the lowest yield of dry leaf (13 June). Maximum and minimum price for one kilogram of tobacco were obtained for transplanting dates April 4th and June 3rd، respectively and there was 1. 5 $ difference per kg. Maximum length and width of leaves was obtained on May 4th. Maximum percentage of leaf nitrogen (2. 3%) was seen for June 3rd that was 39. 2% more than April 14th (1. 4%) and the maximum percentage of potassium (%2. 25) was 41. 7% higher than April 24th (the lowest percentage of potassium). Dry leaf yield had positive and significant correlation with leaf number، plant height and gross income.