Nutritional Management of Cereals Cropped Under Irrigation Conditions

Conclusión

Finally, the information provided in this chapter allows calculating fertilization rates in cereals using objective measurement tools, such as the productivity level and soil chemical properties, being interrelated contribute to achieving economically adequate yields with an environmental component that allows reducing the negative effects associated with incorrect nutrient use.

 

Response of rice to increasing nitrogen rates in five soils with different mineralizable nitrogen levels

Conclusions

To determine the N rate to be used in ‘Zafiro’ rice cultivation in the area included in this study, N mineralization capacity and yield potential of each soil must be considered and thus optimize factors such as harvest index and grain sterility, which are closely associated with grain yield. Of the three N rates evaluated with the ‘Zafiro’, the best response to N rate, effect on harvest index, and grain sterility in most of the soils under study was 80 kg ha¡1.

Anaerobic Incubation Without Shaking Over a Prolonged Period as a Method to Determine Mineralizable Nitrogen in Rice Soils

ABSTRACT

Fertilization rates of nitrogen (N) in rice crop are based on crop needs and the capacity of the soil to supply it, which is determined by several methods. This study evaluated a method of anaerobic incubation without shaking for extended periods of time. Three rice soils of the Inceptisol, Alfisol, and Vertisol orders were fertilized with N rates of 0, 80, and 160 kg ha-1 and
incubated for 0, 7, 14, 21, and 28 d at 20 and 40ºC. The methodology also used short−term anaerobic incubation and constant shaking for 7 d at 40ºC. Field experiments were conducted with rice in the same soils with equal N rates; and extracted plant N was compared with mineralized N. Results indicated that the methodology without shaking is comparable to the constant shaking procedure for short-term incubations. However, incubations without shaking for longer periods of time had the highest relation to crop extracted N.

Keywords: paddy rice soils, nitrogen mineralization, anaerobic incubation method.

Evaluation of genetic effect on physicochemical properties changes of Wx near isogenic lines of Y58S in rice

CONCLUSIONS

There was exponential and positive significant correlation between biomass an N uptake and leaf area index of ratoon rice and normalised difference vegetation index (NDVl) after heading of main rice. These results indicated that NDVI values after heading of main rice can better reflect changes of physiological indexes in ratoon rice. However, these regression models need to be further verified it before it would be applied in ratoon rice.

Genetic diversity, identification, and certification of Chilean rice varieties using molecular markers

Thc polymorphism level detected by simple sequence repeats (SSR) is generally medium to low among INIA commercial rice Oryza sativa varieties. Thi is supported by the diversity parameters, such as the number of alleles (3.50) and polymorphism index content (PlC. 0.50). The highest PIc was positively by SSRs. Given this situation, it is important to continuously introduce germplasm from other regions to increase the Rice Breeding Program’s genetic base.
Genetic clustering of varieties using SSR with Roger coefficient determined the separation of japonica and
indica rice. This clustering was also related to thc type of grain length/width; short/wide, long/wide, and long/narrow.

A set of SSRs was defined to allow the identification and certification of O sativa varieties, including INIA and foreign varieties.

Relationship between mineralized nitrogen during anaerobic incubations and residual effect of nitrogen fertilization in two rice paddy soils in Chile

CONCLUSIONS

We have shown that the index of N uptake, as a result of the residual effect from the previous fertilization, allows determining the quantity of N that can be saved for the following season. Soils incubated at different time lapses and temperatures generate values of mineralizable N. Therefore, the correlation between N uptake and mineralized N are good measures to estimate the best incubation  methodology  that  reflects  field  conditions.

Thus, these indexes will greatly contribute to save amounts of N to each 1 mg N kg-1  mineralized for the Alfisol and Vertisol, respectively.

Increasing nitrogen rates in rice and its effect on plant nutrient composition and nitrogen apparent recovery

CONCLUSIONS

Applying increasing N rates in the ‘Zafiro-INIA’ rice crop positively affected total DM production and its P, K, and Mg concentrations, while whole-plant N and Ca concentrations were not affected. Whole-plant P and K concentrations had different responses when N was added to each soil associate to its chemical properties. The Mg concentration exhibited an erratic effect, but it was not affected by the N rate in most soils. The value of NARE was not affected by the applied N rate, but the highest value was generally achieved with the lowest N rate used. Finally, the results of this study allow the characterization of whole-plant macronutrient composition of ‘Zafiro- INIA’, which corresponds to 5.1-7.7 g N, 1.3-1.8 g P, 5.4-10.8 g K, 1.68-2.57 g Ca, and 0.81-1.45 g Mg kg-1 total DM.

Effects of elevated air temperature on physiological characteristics of flag leaves and grain yield in rice

CONCLUSIONS

High air temperature (HAT) significantly decreased SPAD values (relative content of chlorophyll), soluble sugar and protein contents of leaves and grain yield, while enhanced malondialdehyde content in leaves under field condition. Therefore. we can conclude that HAT stress reduces the amount of assimilates produced by photosynthesis and accelerates the senescence of flag leaves, which are key causes of the decline of rice grain yield.

Evaluación de la tolerancia al frío en genotipos de arroz chileno en fase de germinación.

CONCLUSIONS

Rice germination under low temperatures induced a decrease in coleoptile length growth in ali evaluated genotypes. Genotype ranking. principal component. and cluster analysis based on coleoptile length allowed us to find differences in cold tolerance among rice genotypes. Of the Chilean varieties, ‘Diamante-INIA’ showed high cold tolerance. and ‘Oro-INIA’ and ‘Brillante-INIA’ showed an intermediate cold tolerance. By using this methodology. we found only three experimental lines with cold tolerance similar to · Diamante-INIA», and all the other experimental lines exhibited intermediate to low cold tolerance. These results showed an interesting difference in che cold tolerance of sorne Chilean genotypes ai the germination stage. thus confirming the need to evaluate the rest of the germplasm of thc Rice Breeding Program.

SOIL POTENTIALLY MINERALIZABLE NITROGEN AND ITS RELATION TO RICE PRODUCTION AND NITROGEN NEEDS IN TWO PADDY RICE SOILS OF CHILE

CONCLUSIONS

To obtain a good estimate of soil ammonium nitrogen availability for the rice crop and optimize application rates of N fertilization, the soil incubation technique should consider N applications similar to the rates used in field conditions. Additionally, the anaerobic incubation time could fluctuate between 14 and 21 days. The results of this study allowed us to obtain an N optimization model specific for both soil evaluated. However, to adjust this suggestion for each paddy rice type of soil, a higher number of studies must be undertaken. The adjustment of fertilizer applications to plant requirements will decrease both the risk of contamination of surface and underground water and N gaseous emissions, as well as the reduction on the use of energy in rice production.