Two field experiments were conducted during the kharif (rainy) season of 1999 and 2000 on a loamy sand soil to study the effect of various pre- and post-emergence herbicides on the weed infestation and grain yield of soybean. The presence of weeds in the weedy control plots resulted in 58.8 and 58.1% reduction in the grain yield in the two years compared to two hand weedings (HW) at 30 and 45 days after sowing (DAS), which gave grain yields of 1326 and 2029 kg ha-1. None of the herbicides was significantly superior to the two hand weedings treatment in influencing the grain yield. However, the pre-emergence application of 0.75 kg ha-1 S-metolachlor, and 0.5 kg ha-1 pendimethalin (pre-emergence) + HW 30 DAS were at par or numerically superior to this treatment. There was a good negative correlation between the weed dry matter at harvest and the grain yield of soybean, which showed that effective weed control is necessary for obtaining higher yields of soybean.
Authors:H. El-Sharkawi, M. Irshad, A. M El-Serfy, T. Honna and et al.
The use of poor quality water for agriculture is now receiving major attention especially in arid and semi-arid regions. This experiment was carried out to evaluate the effects of different irrigation water qualities on the grain yield and nutrient uptake of rice and on the heavy metal concentration in the grains. Six water treatments were applied at intervals of three days, involving either fresh water (FW), drainage water (DW), mixed water (MW), fresh water followed by drainage water (1FW + 1DW), two applications of fresh water followed by one of drainage water (2FW + 1DW) or one application of fresh water followed by two of drainage water (1FW + 2DW). The rice grain yield and the uptake of nitrogen (N), phosphorus (P) and potassium (K) were determined. The grains were also analysed for the concentration of nickel (Ni), cadmium (Cd) and lead (Pb). The results showed that the grain yield, the uptake of N, P and K in the plant biomass and the concentration of heavy metals in the grains were significantly affected by the water quality. The rice grain yield exhibited a close correlation with the water quality. The highest grain yield was obtained in the FW treatment and the lowest yield in the DW treatment. The uptake of N, P and K was detrimentally affected by poor quality water. However, the uptake trend for these elements was similar across all the irrigation treatments. The concentrations of heavy metal in the grains were significantly higher in plots irrigated with poor quality water. Among the treatments the cumulative concentrations of heavy metal were in the order of: DW ≯1FW + 2DW ≯ MW ≯ 1FW + 1DW ≯ 2FW + 1DW ≯ FW. This study showed that there is a potential risk of heavy metal contamination in rice crops treated with poor quality water. The lower grain yield after irrigation with poor quality water could be due to the disturbed mineral nutrition or to relatively higher salt toxicity.
Authors:A. Ding, F. Cui, J. Li, C. Zhao, L. Wang, X. Qi, Y. Bao, X. Li and H. Wang
Grain yield (GY) and yield components (YC) were investigated using two F8: 9 RILs, comprising 229 and 485 lines, respectively. A conditional analysis was conducted to generate conditional values for GY independent of each YC. Then both unconditional and conditional values were analyzed to map QTLs with additive effect. In both RILs, up to 23 unconditional and conditional QTLs were detected. However, only two QTLs were identified repeatedly among environments. All QTLs, except for 4 detected in unconditional mapping, were also identified as conditional QTLs, whereas a number of QTLs were additionally detected in conditional mapping. The number of QTLs detected that affected GY was different with respect to component-special influences. Our results revealed that the contributions of YC influencing QTL expression related to GY differed.
We aimed to study the influence of soil water deficit on gas exchange parameters, dry matter partitioning in leaves, stem and spike and grain yield of durum (Triticum durum Desf.) and bread (Triticum aestivum L.) wheat genotypes in the 2013–2014 and 2014–2015 growing seasons. Water stress caused reduction of stomatal conductance, photosynthesis rate, transpiration rate, an increase of intercellular CO2 concentration. Photosynthesis rate positively correlated with growth rate of genotypes. Drought stress caused adaptive changes in dry matter partitioning between leaves, stem and spike of wheat genotypes. Stem dry mass increased until kernel ripening. Drought stress accelerated dry mass reduction in leaves and stem. High growth rate of spike dry mass was revealed in genotypes with late heading time. Spike dry mass positively correlated with photosynthesis rate and grain yield. Generally, bread wheat is more productive and tolerant to drought stress than durum wheat.
Authors:A. Morgounov, A. Abugalieva and S. Martynov
Winter wheat yield in three administrative regions of Kazakhstan (Almaty, South Kazakhstan, and Zhambyl) was analyzed during 1972-2009. Yield gains were greatest during 2000–2009, but absolute yields remain low (1.5–1.7 t/ha) and much below the production potential. Changes in important weather parameters over the same time period were also analyzed. Results indicated significant (15–20%) warming in winter and spring, as well as some increase in precipitation (spring and annual), especially in the last ten years. Increased temperatures in winter and precipitation in spring/annually were positively correlated with winter wheat yield, while increased temperatures in May had a small but negative effect on grain yield. Data from the four stations of the official variety testing system from 1972–2009 were also analyzed to evaluate the effect of variety on yield and quality. Genetic gain of the varieties released in the 1990s and 2000s, compared to Bezostaya 1 (1960s), was around 30%. However, the bread-making quality of new varieties, as well as the overall grain quality in variety trials, were reduced in protein content, with deteriorated dough physical properties, and therefore did not meet superior class requirements. Genetic diversity (coefficient of parentage and Shannon’s diversity index) of the winter wheat varieties tested in the 2000s was broader compared to the 1970s and 1980s, reflecting enhanced international cooperation and germplasm exchange. A negative association between genetic diversity parameters and some quality traits can be attributed to the utilization of more diverse high yielding parents with limited grain quality potential. Further yield increases and reductions in the yield gap should be based on improved agronomy, and the use of broadly-adapted varieties, with resistance to the biotic and abiotic stresses likely due to climate change.
Stone mulch offers potential benefits for water conservation in many rain-fed agricultural systems of the arid regions. The effects of stone mulch on transpiration and grain yield were examined for a durum wheat crop grown under soil water deficit stress. In a greenhouse trial, stone mulches with two levels of ground coverage significantly decreased soil-surface evaporation and increased crop transpiration. The transpiration increase contributed to increases both in biomass and grain yield. Field experiments over two cropping seasons confirmed yield increases of 12% in soil half-covered and 24% in soil fully-covered by stones. These significant yield increases indicate the potential usefulness of stone mulch technology in rain-fed cereal cropping. It is suggested that stones should not be removed from cereal fields unless their presence obstructs management severely. It remains to develop technologies for effectively managing soils containing large numbers of sizable stones in order to obtain the benefits of the potential yield increase associated with their presence on the soil surface.
Abbad, H., Jaafari, S.E.L., Bort, J., Araus, J.L. 2003. Comparison of flag leaf and ear photosynthesis with biomass and grainyield of durum wheat under various water conditions and genotypes. Agronomie