International Journal of Plant Production
Volume:2 Issue: 3, July 2008

The present study was undertaken to evaluate direct and indirect selection criteria for the improvement of grain yield and quality components in Chenopodium quinoa Willd. Correlated response (CR) and relative selection efficiency (RSE) were estimated for grain yield and three quality components, grain protein, grain carotenoid and leaf carotenoid based on different contributing traits. Stem diameter, chlorophyll a, total chlorophyll and leaf carotenoid had high CR and RSE values for grain yield indicating the effectiveness of these traits in increasing grain yield. Grain protein and grain carotenoid exhibited negative CR and RSE values for grain yield indicating that direct selection for grain yield would lead to a slight decrease in these quality characters. Grain size was not of much significance either in increasing grain yield or any of the quality components. Grain yield can also be increased through indirect selection for stem diameter, while leaf pigments are likely to play a major role in enhancement of quality traits like leaf and grain carotenoid

A standard description of growth stages for crops/plants is necessary not only for determining and improving cultural practices, but also to facilitate enhanced communication among producers, researchers, and educators. It also could help in unifying experimental results. Many different descriptions of growth stages are currently available for many crops, but there are no codes for sesame (Sesamum orientale L.). To define the standard description, common characteristics of sesame genotypes, including main stem node, flower bud appearance, flower bearing and flower opening, and capsule and seed formation, are used. Four principal stages were identified for the crop growth cycle and secondary stages were defined for each principal stage. The three digits stage code uses the first digit to represent the principal stage and the second and third digits shows for the secondary stages. A period “.” or a comma “,” are used to separate the principal and secondary stage digits. All stages are also documented with hand-drawn illustrations. In this system, a three digit decimal code is assignment to each individual crop development cycle and the complete crop growth and development cycle from seed, as planted, to seed, as harvested, is described. The presented scale is a user friendly tool to recognition of sesame population stages of development. It helps researchers and farmers to choose the best agricultural practices and applying then in farms and research plots.

This research was conducted in order to study the effects of iron fertilization on yield and chemical composition of date palm var. ''Piarom'', on 54 trees in Haji-Abad research station of Hormozgan Province. Trees were 12 years old and research treatments were consisted of: 1-Control treatment 2- Soil surface application of Fe in two levels 3-Application of Fe as localized placement method (Chalkood method) in two levels 4-Fe injection into the trunk of tree in four levels. The experiment was performed as a randomized complete blocks design with nine treatments and three replications in four years. Trees were pollinated according to the custom of the region and irrigated through drip system. Fruit thinning was done with extra clusters deletion regarding the ratio of eight leaves to one cluster. Production was harvested and weighted each year in October, the second half. Chemical and physical analysis of leaves and fruits were also done. Obtained raw data were analyzed statistically and means were compared with each other via Duncan,s multiple range test using MSTATC software. Results showed that in most cases, injection of 25 g FeSO4 tree-1 into the trunk caused the best results. Other injection treatments were placed in second class. Localized placement of iron fertilizer was the next treatment from the viewpoint of desirable effects. Finally, soil surface application appeared as an inapt method because it was statistically similar to control treatment, in most cases.

Broader environmental tolerance associated with mixed population of soybean (Glycine max Merr.) cultivars may increase soybean yield potential and play a significant role in yield stability. A field study was carried out to assess whether intercropping of two commonly used cultivars of soybean with different morphological characteristics may increase seed yield in Iran. A split-plot design was used with three replications. The main plots were 3 densities; 23.8, 33.3, and 55.5 plants m-2. Sub-plots consisted of intercropping ratios row by row of 100:0 (pure stand of Harcor), 75:25, 50:50, 25:75, and 0:100 (pure stand of Bonus) of Harcor and Bonus cultivars, respectively. The results indicated that the highest seed yield was obtained from 50:50 ratios of the cultivars which had land equivalent ratio (LER) above 1.11. Calculation of LER revealed that seed yield in treatment HBHB was 11% higher than the pure stand. The superiority of intercropping over pure stands occurred only in the highest plant density. Intercropping ratio showed no significant effect on any of yield components. However, pod number per plant was decreased with increasing plant density

The seasonal changes of leaf physiological traits and its relationship with abiotic factors (photosynthetic active radiation-PAR, leaf temperature-Tleaf, air temperature-Tair, Tleaf - Tair- ΔT) were studied on sugar beets grown under the semi-arid conditions of central Greece. Sugar beet (Beta vulgaris L.) cv Rizor was established in a Randomised Complete Block design experiment for two years (2004-2005). From early June till the end of October, 11 determinations of leaf physiological traits (intracellular to ambient CO2 concentration-ci, transpiration rate-E, stomatal conductance-gs, net photosynthesis-A, instantaneous water use efficiency-A/E, photosynthetic water use efficiency-A/gs, chlorophyll content-SPAD, carbon isotope discrimination- Δ, N concentration and specific leaf area-SLA) took place. Temperatutes (Tleaf and Tair) and ΔT were higher in 2004 when water budget (WB, precipitation irrigation – evapotranspiration) was more negative. Also, seasonal mean of carbon isotope discrimination (Δ) and net photosynthesis (A) were lower in 2004 to compare to 2005. A gradual decline with the progress of the growing season was found for A, Δ, gs, E, SLA and leaf N concentration while the adverse trend was evident for water use efficiencies (WUE, A/E and A/gs). PAR was positively related with gs and E and negatively with A/E. Temperatures (Tair and Tleaf) had a positive effect on E and a negative one on A/E. High temperatures (35-37 ºC) degraded leaf chlorophyll but temperatures higher than 37 ºC tended to increase chlorophyll content. ΔT (transpirational cooling) was negatively related with gs, E, and A and positively with A/E and A/gs. Both E and A were regulated by gs which was kept higher or slightly lower than 0.10 mol m-2 s-1, a limit indicative of severe drought in C3 species. Positive relationships were found between A, leaf N concentration and SLA. SLA is an indicator of resource-use strategy and can provide useful information about abiotic factor effects on sugar beet physiology and yield. Δ was negatively related with A/gs showing that it can be an indirect assessment of WUE at leaf level.

Effects of the mycorrhizal fungus Glomus intraradices on establishment of subterranean clover (Trifolium subterraneum L.) seedlings in saline conditions were studied in a glasshouse experiment. Growth and nutrient uptake were determined 10, 20 and 30 days after transplanting of mycorrhizal and nonmycorrhizal matched seedlings into soils with five different levels of salinity. Mycorrhizal plants had greater shoot and root dry weight than nonmycorrhizal plants. The enhancement in seedling dry weight due to mycorrhizal fungi was greater under high salinity levels. The detrimental effects of salinity stress on plant growth were appeared immediately after application low salinity stress to nonmycorrhizal plants (3.5 dS/m), but it was only observed in mycorrhizal plants at 7.5 dS/m and above. Mycorrhizal fungi increased P concentrations in shoots and roots compared with nonmycorrhizal plants particularly at 12 dS/m. Root K/Na ratio was also increased in mycorrhizal plants, possibly contributing to salinity tolerance. Calculation of mycorrhizal responses in terms of plant dry weight, P and K contents showed that the beneficial effects of mycorrhizal fungi on seedling salinity tolerance are due to different mechanisms at different stage of growth: increased P uptake during early growth and increased K uptake at the later stages. Results are discussed in the context of application of mycorrhizal inoculation to revegetation of salt affected lands.

In order to study the effects of post-anthesis heat stress and nitrogen levels on grain yield and yield components of wheat genotypes, two separate field experiments were conducted in delayed and optimum sowing dates under Ahvaz conditions (2006-2007). The Ahvaz site located in south west of Iran (32°20'' N, 40°20'' E) with subtropical climate condition. The experiment site had a moderate winter and dry and hot summer. Plants in delayed sowing date experienced heat stress at post-an thesis growth stage. Each split-polt experiment had a randomized complete block design with three replications. The application rates of N at three levels (50, 100, and 150 KgNha-1) were assigned in main-plots. Sub-plots were consisted of six bread and durum wheat genotypes. The results indicated that the grain yield reduction in 50 and 100 KgNha-1 compared with 150 KgNha-1 treatments was 41% and 21% under optimum and 44% and 26% under heat stress conditions, respectively. In all genotypes, grain yield and 1000-grain weight (TGW) reduction under post-anthesis heat stress conditions was 33% and 42%, respectively. The highest and the lowest grain yield reduction due to heat stress were observed in Star (39%) and Vee/Nac (27%) genotypes. The Grain yield reduction in nitrogen deficiency treatments and post-anthesis heat stress was due to significant reduction in number of grains. m-2 and TGW, respectively. In nitrogen deficiency treatments grain number per area was reduced due to reduction in number of fertile florets. Spikelets-1, spikes. m-2, and spikelets. spike-1. Further research are recommended for full understanding the effects of heat stress and low N level on yield and yield components of recommended wheat genotypes under agroclimatic conditions such as south west of Iran.

A water simulation model (WaSim) to simulate the growth and development of Amaranthus cruentus as well as the components of water balance for a typical sandy-clay-loam soil of Akure has been described. Dry season experiments were carried between January and March of 2005 and 2006. Amaranthus seeds were established on the field and three irrigation water managements were imposed on the crop to determine its response to water deficit at its different phenological stages. Amaranthus growth and development, evapotranspiration (ET) and rooting depth were calibrated by fitting the most sensitive variables to obtain the corresponding model output. The model simulated crop growth and crop cover well, the coefficient of determination r2=0.9 and the difference between simulated and measured root depth is not significant at P<0.001. The actual evapotranspiration (AET) from the model prediction and the measured value gave a fairly high coefficient of correlation r=0.7 at P<0.001. The mean bias error (MBE) and the root mean square error of yield estimates between the measured and the model prediction are -0.4444 and 1.35 respectively at P < 0.001. The model was considered effective and appropriate for daily simulation of water balance, water requirement of crops and in climate effects on crop production.