Subapical ears are largely responsible for grain yield variations in prolific maize (Zea mays L.) grown under conditions favourable for the expression of prolificacy trait, but limited information ...exists on yield components contributing to yield responses. A field experiment was conducted to determine the yield components of apical and subapical ear in prolific maize after various pollination treatments at two plant populations. Hybrid Pioneer 3733 was grown in the perfect stands of 71 428 and 35 714 plants ha−1. Three pollination treatments were carried out: (i) free pollination; (ii) subapical earshoots were covered to prevent pollination; and (iii) apical earshoots were covered to prevent pollination. Grain yields of free pollinated plants were by 50.1 % larger at low plant population (265 g per plant) than at high plant population (177 g per plant) due to a 45.3 % increase in kernels per plant, whereas 1000‐kernel weight slightly increased by 3.3 %. These increased kernels per plant at low plant population were, in part, the result of kernel increments on apical ear (10.1 %), and mainly associated with kernels from subapical ears that did not occur at high plant population. At low plant population, the total grain yield per plant was reduced by 94 g (35.5 %) after the apical ear was bagged to prevent pollination, but only 52 g (19.6 %) when the subapical ear was bagged. When subapical ear development was stopped at low plant population, grain yield on apical ears increased by only 3.9 % as a result of heavier 1000‐kernel weights, clearly demonstrating limitations in kernel set and size. After grain development on apical ear was prevented, subapical ear enlarged to 80.3 % of maximum apical ear yield because the former had, on average, 2.5 % lighter 1000‐kernel weight and 17.5 % fewer kernels than the latter. Ears did not differ in row number when only apical or subapical ear was developed on plant, whereas subapical ears tended to have fewer rows than apical ears when both were present on the same plant. Our results showed that: (i) plant population affected all yield components on both apical and subapical ear except row number; (ii) the occurrence of subapical ear is triggered by achieving maximum potential kernel set on apical ear; and (iii) subapical ear is inferior in potential grain yield to apical one even when the latter was prevented from pollination.
A simple, but highly accurate, sampling method for the measurement of frequency by means of a digital multimeter (DMM) or a digital voltmeter (DVM) is explained both theoretically and from the ...applicative point of view. The mathematical background is given in short form, and comparison with other solutions is provided. High accuracy and behavior regarding random errors are foreseen by computer simulation and then proved in real laboratory measurements. Finally, verification of factory time-base specifications of sophisticated equipment is shown taking an HP 3458A DMM as an example device under test.
The possibility of using high-resolution digital voltmeters for AC voltage measurements at a frequency of about 16 Hz is presented. The method of approximate synchronous sampling is used where each ...sample is measured as the mean value of the one-third cycle of a period. From the samples, the RMS value of the "derived" sine is determined using subsequent numerical synchronization, while the phase angle of the first sample is calculated as regression line coefficient. Corrections of phase differences between two voltmeters were determined using only one source in cascade measurements.
The digit voltmeter (DVM) input and leakage resistances have been analyzed in the DVM-based resistance measurement system using one or two DVMs. The results are given both theoretically and ...experimentally. Shunting errors due to DVM-input and leakage resistances were substantially reduced by using a proper measurement method. The method is being further investigated for measuring high-ohm standard resistors.
The possibilities for adapting the existing electrostatic device known as the voltage balance ETF-84, to work with a voltage of 100 kV and a weight of 1 kg, are considered. A few theoretical ...analyses, experiments, and computer simulations have been carried out to define the measurement procedure needed at the required level of uncertainty of 1 part in 10/sup 8/. These analyses identified which parts of the balance itself and of the high voltage electrode isolation have to be reconstructed, as well as how the associated high voltage resistor has to be designed for this purpose.
Voltage balance for replacing the kilogram Bego, V.; Butorac, J.; Poljancic, K.
IEEE transactions on instrumentation and measurement,
04/1995, Letnik:
44, Številka:
2
Journal Article, Conference Proceeding
Recenzirano
The paper gives a short description of the basic principle of work of the ETF Voltage Balances, as well as the measurement procedures enabling the absolute determination of the Volt. We review ...previous results, and estimate the expected uncertainties for further experiments using the so-called charge-method. We review the calibration of the standards used with the balance. We have successfully started a new series of measurements at the end of 1993, and expect to report on the results at the end of 1994.< >
In broadly conceived long‐term experiments, tobacco was grown in monoculture and with different crop rotations. This paper presents results in terms of the yields achieved and the major yield ...components for the crops grown, and the proportion of particular tobacco quality classes obtained. In addition to tobacco monoculture (initially only fertilized and later also unfertilized) as the key crop, different types of crop rotations included, besides tobacco, the following crops: winter wheat, maize, soybean, oil‐seed rape, and red clover. Experiments involved two 2‐year and two 4‐year crop rotations, and a 3‐year, a 5‐year, and a 6‐year crop rotation. Experiments were set up on luvic semigley on multilayered Pleistocene sands. Average 10‐year results suggest that there is an advantage of crop rotation over monoculture for tobacco leaf yields. The influence of different crop rotation types on yields of other crops was variable, tending towards higher values as the number of crops in rotation was increased. Values obtained for yield components should be considered from two angles: some of the values were primarily influenced by genetic factors, while others were influenced by ecological factors, including crop rotation as an overall biological buffer. With regard to quality classes (IB‐III), the growing of flue‐cured tobacco in crop rotation represents a great advancement relative to its growth in monoculture, even in a narrower crop rotation.
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