فهرست مطالب mohammad taghi karbalai agha molki

Phosphorus (P) is the second most important macronutrients and zinc (Zn) is the most important micronutrients that their deficiency is the most important global nutrient disorder in the world paddy fields. The current field study was conducted to explain the effect of Zn and P foliar application on Zn and P content of rice grains and more broadly, grains bio-fortification (Zn and protein content).

The three factors factorial experiment was conducted in a completely randomized block design with three replications in 2017-2018 at research field of the rice research institute of Iran, Rasht. The experimental factors were: varieties at two levels (Hashemi (local) and Guilaneh (improved) varieties), Phosphorous at three levels and Zinc at three levels.Also, the experimental treatments were: 1- no zinc foliar application (control-tap water foliar application), 2- the foliar application of 0.5% zinc sulphate (22%) at the strat of booting, 3- the foliar application of 0.5% zinc sulphate (22%) at the strat of booting and the start of grain filling stages; 4- no P foliar application (control-tap water foliar application), 2- the foliar application of 0.5% P(mono potassium phosphate- laboratory brand) at the strat of booting, 3- the foliar application of 0.5% P at the strat of booting and the start of grain filling stages.

The results of analysis of variance indicated that all the applied treatments and their interactions significantly influenced the morphological, yield and yield components, Zn and protein contents of rice grains. The results revealed that the foliar application of Zn and P the strat of booting and grain filling stages increased panicle length in Hashemi (7%) and Guilaneh (12.94%) cultivars, filled and unfertile grain number of Guilaneh (35.23- 6.40%) and Hashemi (40-35%) cultivars. Also, the foliar application of Zn and P (alone) increased the grain yield about 7 and 11.10%, respectively, and their application the strat of booting and grain filling stages increased biological yield of Hashemi and Guilaneh cultivars about 19.22 and 25.98%, respectively. The highest content of grain Zn and protein content were recorded at by the strat of booting and grain filling stages foliar application of Zn about 27 and 11 present, respectively.

It can be concluded that the foliar application of Zn and P at the strat of booting and the start of grain filling stages might enhanced the studied rice cultivars yield and yield component and more broadly the grain quality.

Despite the P vitality for rice cultivation, its recovery index in paddy soils is very low and less than 25% of added P, and the rest goes out of reach of rice plant through the P fixation by soil particles at different fractions. Also, despite abundant studies on the effect of basal soil P application, we face a lack of knowledge on research findings of the P splitting application and its effect on soil Zn concentration and tissues Zn content. Thus, the current research project was done to explore the effect of P splitting application at flooded conditions on the soil and rice plant tissues P and Zn variation trend at the different rice growth stages of two more common varieties (Hashemi and Guilaneh varieties).

The outdoor pot experiment was conducted on a three factors factorial experiment in a randomized complete block design with three replications in 2017 at the research farm of the rice research institute of Iran, Rasht. The experimental treatments were: phosphorus fertilizer split application at five levels, soil at two levels, and rice varieties at two levels (Hashemi (local variety) and Guilaneh(improved variety)), The P application treatments were: control (no added P), 100% basal, P split application at 50% basal and 50% at 20 days after transplanting (DAT), P split application at 50% basal and 50% at 60 days after transplanting (DAT), P split application at 50% basal, 25% at 20 days after transplanting, and 25% at 60 days after transplanting.

The results indicated that the highest soil available P and Zn concentrations were recorded at the flowering stage about 95.3 and 90.10, and 8.6 and 8.7 mgkg-1by two and three P split for Hashemi and Guilaneh, respectively. Also, the maximum P of rice grain was obtained about 0.17 and 0.20 mgkg-1 for Hashemi and Guilaneh, respectively. The Zn content of rice grain at P split pots was significantly more than control and 100% basal application. The highest agricultural recovery (13.31 and 12.72), physiological (693.19 and 740.10) and physiological-agricultural efficiency (482.00 and 753.00), P use efficiency (5.34 and 5.66), and apparent recovery (1998 and 1272.22 kg kg-1) were found for Hashemi and Guilaneh, respectively, in the two and three P split application. Furthermore, stepwise multiple regression analysis revealed that the soil available P concentration at ripening stage, Zn content of the grain, and Zn concentration at rice aerial parts can explain 52% of grain yield variations for studied rice cultivars.

The three-stage P splitting (50% soil basal, 25% 20 DAT, and 25% 60 DAT) increased the Zn content of the Hashemi variety by about 54.72% at slit loam soil, whereas the Guilaneh rice variety was received a 37.5% increase in Zn content of grain in silty clay through two-stage P splitting (50% soil basal and 50% 20 DAT) compare to control (100 % basal). It can be concluded both three and two-stage P splitting might be positively significantly effective on rice grain nutritional quality.

The rapid growth in world population and its consequent increasing food demand require a scientific approach to paddy field productivity. To further increase rice production, the best solution is enhancing the rice yields per unit area. There are numerous integrated indices that can clarify the soil conditions and fertility characteristics, in which the integrated fertility index (IFI) is more practical. Therefore, the current study will explore soil fertility status of paddy field using IFI equation, and more broadly to issue suitable solutions for paddy soil management. This study was undertaken at Goldasht research station of the rice research institute of Iran-Amol. One hundred and twenty-eight paddy soil composite samples of plowing layer (depths of 0 to 30 cm) with a constant interval were collected to analyze for some physical and chemical properties based on rice soil requirements. Fuzzy logic theory, Principal component analysis (PCA) and IFI concepts were used for quantitative ranking of qualitative soil characters, weighing of soil properties and integration of studied soil characters, respectively. The results indicated that IFI values varied from 0.03 to 0.20. The studied paddy fields were divided into 4 individual parts through IFI values mapping method. At lower values of IFI (low soil fertility), pH, available P, OC and less broadly total N were lower than their critical levels for proper rice growth and development. Interestingly at higher values of IFI, OC and total N limitation still existed. It can be concluded that organic carbon limitation in all studied plots had negative and unavoidable effects on not only paddy soil fertility status (a vital role for sorption and desorption of soil nutrients), but also soil physical characters (enhancing soil structure, porosity, and water retention). The findings of current study also showed that the integrated fertility indices not only can show the most important limitations for rice production but also can issue the effective solutions to remediate these limitations. Key words: Rice, soil fertility, integrated fertility index, fuzzy logic, geostatistics