CROP PHYSIOLOGY
Year:2012 | Volume:4 | Issue:13|Papers Count:11

Sunflower is one of the most important agronomical plants in many warm region farming systems that its culture has developed in the variable climatic regions. The replacement of old sunflower cultivars by new, high yield and early maturity hybrids and also the developing of second culture of sunflower are two major plant breeding and agronomic strategies to increase sunflower production in mild cold climates of Iran. In order to study the possibility of second cropping of sunflower in the mild cold region of Kermanshah, a split plot experiment based on complete randomized block design with 3 replications was carried out in Islamabad Research Station, in 2010. Planting dates including 10th Jun, 26th Jun and 11th July were assigned in main plots and sunflower hybrids, including Azargol, Farrokh, (SHF-81-85), SHF-81-90 and Allstar were allocated as subplots. The first planting date, 10th June, was the most suitable planting date. New SHF-81-90 and and Farrokh hybrids showed the highest and lowest of total dry matter and leaf area index amounts, respectively. Total dry matter, leaf area index, relative growth rate, crop growth rate and net assimilation rate in the first planting date and SHF-81-90 hybrid had the greatest amounts.

The objective of this study was to examine the effect of planting date and heat stress during flowering on yield and grain yield components of 3 spring canola cultivars. The experiment was conducted at Shoushtar Islamic Azad University during 2010-2011 cropping year. The experiment was conducted as a split plot randomized complete block design with 4 replications in Shoushtar Azad University in 2011-2012 cropping year. Three planting date 21 November, 10 and 30 December were as main factors and three Canola cultivars Hyola 308, Sarigol and Heros as subfactors. The results showed that biological and grain yield as well as yield components (except the number of seeds per silique) decreased significantly with delay in sowing date. Grain yield and yield components were significantly different among cultivars, however biological yield was not. Hyola 308 and Heros cultivars produced the highest and lowest (3189. 1 and 2017. 5 kg/ha) grain yield, respectively. Among grain yield components, silique number per plant was more indicator of cultivars yield than two other components. However, seed number per silique was effective on graining yield of Hyola 308 cultivar. Early cultivar (Hyola 308) in first planting date 21 November and late cultivar (Heros) in late planting date 30 December produced the highest (3630. 3 kg/ha) and the lowest (1310. 2 kg/ha) grain yields, respectively. Based on the results of this study, middle and late maturing cultivars of canola are not suitable for khouzestan climatic conditions, and early maturing cultivars can be more useful to avoid heat stress.

In order to evaluate the relantionships between grain yield, yield components and other attributes relating to grain yield, three barley cultivars (Mahor, Ezeh and Regional Dopar) effected by five planting densities of ( 100, 200, 300, 400 and 500 seeds/m2), a factorial design with three replications in RCBD was carried out at KhorrmAbad agricultural research station in 2006-2007 cropping year. The results showed significant difference among cultivars in regards to morphological characteristics, yield components and grain yield. While the highest number of grains per spike, leaf area index, harvest index, and the highest plant height belonged Ezeh cultivars. Increasing plant density reduced plant height and spike length and increased biological yield and number of spikes per square meter, significantly. But it had no significant affect on grain yield, due to the self-regulatory mode by changing the tiller grinding grains such as barley. Mahor cultivar with an average grain yield of 5617 Kg grain per hectare and 15680 Kg of biomass in hectare due to greater number of spikes per square meter (528 spikes) was better than other cultivars. Grain yield had positive and significant correlation with the number of spikes per square meter (r= 0.47**) but was negatively correlated with leaf area index and 1000 grain weight. Regarding to the obtained results, density of 300 grain m2 can be recommended for barley cultivars in dry land conditions.

In order to the effect of mulch, hand weeding of weeds and plant density on yield and yield components of sweet corn (Sc403) an experiment in a factorial randomized complete block design with four replications was conducted in the farm of Shahid Salemi located in the Northeren of Ahvaz, during 2010. Experiment treatments included Mulch in three levels: control (m1), straw (m2) and bagasses (m3). Weeding in two levels: Non hand weeding (a1) and hand weeding weeds (a2) and density factor of two levels included: density of 60,000 plants per hectare (d1) and the density of 90,000 plants per hectare (d2). The results showed that the use of mulch had significant effect (5%) on biological yield, grain yield, grain number per row, 1000 grain weight, plant height, ear height of Earth's surface, stem diameter and harvest index, and mulch treatments didn't effect on other traits. Application of straw mulch had the highest effect on the meaningful traits. Also hand weeding weeds treatments had significant (5%) difference on grain yield, harvest index, seeds number per row, plant height, ear height of the Earth's surface and steam diameter and other traits didn't effected by factor of hand weeding weeds. The analysis of variance showed that the plant density on grain yield, biological yield, harvest index, seed number per row, 1000-grain weight, ear height Earth's surface and steam diameter had significant effect and it didn't have any effect on other traits. The highest grain yield (306.99 gr / m2) of the density of (90000 plant per hectare) was obtained in hand weeding conditions. At last the interaction of weeding in density and mulch on density had significant effect on biological yield, grain yield, and seeds number per row.

In order to study the effect of foliar application of methanol on chlorophyll a, b, Cartenoied, total Chlorophyll, relative water content and leaf sellular memberane stability of chickpea (Karaj cultivar) under drought stress, a factorial experiment in completely randomized design with three replications was conducted in September 2011 at the Institute of Plant Sciences of Ferdowsi University of Mashhad. The first factor was 5 levels of methanol foliar application control (without foliar application), 20, 25, 30, 35 volumetric percentage (v/v), which Glisin (2 g/lit) was added to all them. Foliar applications was used three times during growth season of chickpea, with 10 days intervals. Second factor were drought stress (25% plantig capacity) and without drought stress (100 planting capacity). Results showed that there was a significant difference between different methanol concentrations regarding to the amount of Chlorophyll a, b Carotenoid, total Chlorophyll, Chlorophyll, a to b ratio, Relative Water Content (RWC), Membrane Stability Coefficien water use efficiency and (P<0.01). Spraying with30% volume level was more effective than the other treatments while caused significant increase in amount of Chlorophyll a, b, total Chlorophyll and Relative Water Content (RWC) compared with to other levels. Interactions between drought stress and Methanol had no significant effect on cartenoied measure and relative water content but on amount of Chlorophyll a, b, total Chlorophyll and Membrane Stability amount of Coefficient (P< 0.05) was meaningful.

In order to study the relationship between grain yield and yield components, correlation analysis and understanding direct and indirect effects of different effective treats on yield, under two conditions of normal irrigation and drought stress, a field study was carried out on 20 lines and advanced genotypes of barley in RCBD and 3 replications at Broujerd Agricultural Research Station in 2009-2010.The study of correlation coefficients showed the highest correlation between seed yield and 1000 - seed weight ( r = 0.85) under normal conditions but seed yield and harvest index ( r = 0.65 ) under moisture tention. Result of path analysis between seed yield and other under studied traits showed that 1000-seed weight had the highest direct effect of (0.69) on seed yield following by harvest index and spike length with low negative indirect effect on yield in normal condition. Harvest index and biological yield had the highest direct effect on yield under tention condition. Relative water content indirectly had high effect on yield through harvest index. Therefore, considering the obtainded results of correlation coefficients and path analysis in the presence of water limitation, harvest index, relaitive water content and biological yield can be used to improve yield.

In order to study the effect of amounts, methods of application and sources of Phosphorus fertilizer on grain yield of wheat as well as total Phosphorus uptake, an experiment was conducted in two cropping years (2007-2009) in Safi-Abad Agr. Res. Cen of Dezful, Iran. The experiment design was a completely randomized block with factorial arrangement with three relplications and 16 treatments. The first factor was at four levels of Phosphorus fertilizer consisting of 0, 0.5, 1 and 1.5 times to Phosphorus fertilizer recommended on the basis of soil testing, equivalent with 50, 100 and 150 kg Phosphorus fertilizer per ha, the second factor consisting of methods of applying Phosphorus fertilizer including band and broadcast and mixed with surface soil and third factors consisting of source of Phosphorus fertilizer type tripel superphosphate and phosphate diamonium. The results showed that Phosphorus different levels and the applying fertilizer type on grain yield, straw yield and 1000-grain weight were significant. The method of fertilizer application on straw yield was significant, only. The highest grain yield (5316 kg ha-1) was due to application of 50 kg Phosphorus fertilizer as phosphate diamonium. Method of P application on harvest index was significant, only. The effect of levels of Phosphorus fertilizer and method of its application on total uptake of Phosphorus was significant. The effect of experiment treatments on Phosphorus utilization efficiency and harvest index of Phosphorus was not significant.

Due to the limited water resources in agriculture, applying any strategy to saving water is very important. One of these strategies is Deficit Irrigation. The purpose of this study is evaluation of drought stress as water holding on yield and yield components of wheat Chamran cultivar at different levels of nitrogen fertilizer and determine strategies to achieve efficient increase of water resources consumpation. This research in 2007-2008 cropping year in the field of Agricultural Research Center of Ahwaz in three irrigation treatments I1 (without stress), I2 (irrigation holding at heading stage) and I3 (Irrigation holding at grain milk stage) and five nitrogen levels N1 without fertilizer, N2= 40, N3= 80, N4= 120 and N5=160 kg N ha was investigated. The experiment conducted as split-plot randomized complete block design with three replications. Results showed that I1 treatment with LAI 7.37 the highest and I2 treatment with LAI 6.27 allocated to the lowest. The I1 treatment with 1828.5 g/m2 produced the highest and I2 treatment with 1368 g/m2 the lowest value dry matter. The results of analysis of variance showed that irrigation treatments on total dry matter, grain yield, straw yield, harvest index, 1000-seed weight, ear number per square meter and number of grains per spike was significant at 1% level, but the amount was not significant on Krvfyl amount of flag leaf. The nitrogen treatments on total dry matter, grain yield, straw yield, harvest index, seed -1000 grain weight, number of grains per spike, spike number per square meter and the rate of Krvfyl flag leaf was significant at 1% level. So treatment I3 with a yield of 48.11 g grain m2 per intake of one cubic meter of water, had the most economical efficiency and treatments I1 and I2 with efficiencies, respectively, 47.02 and 42.38 grams m2 grains per intake of one cubic meter of water were placed in the next categories with significant difference from each other at 5% level.