جستجوی مقالات مرتبط با کلیدواژه « شاخص برداشت » در نشریات گروه « مکانیزاسیون کشاورزی »

Optimal nutrient supply, either chemical or biological fertilizers, can be customized for water availability and paired with correct tillage systems. This approach is necessary to ensure high production in corn (Zea mays L.). To determine possible impacts of nitrogen (N), various irrigation regimes and tillage systems were evaluated on sweet corn (Zea mays L. var Saccharata). Dependent variables were plant growth, yield, water use efficiency (WUE), and soil characteristics. For this purpose, a two-year experiment (2016-2017) was conducted in a split-factorial design, involving randomized complete blocks with three replications at the Agricultural Experimental Station, School of Agriculture, Shiraz University, Shiraz, Iran. The treatments were two tillage systems [conventional (CT) and decreased (RT)] as the main plot. Five N rates were used (0, nitroxin, 150 kg N ha-1, nitroxin + 150 kg N ha-1, and 300 kg N ha-1). The two irrigation regimes were [100% (normal) and 75% of plant water need (PWR)(Kc)] as subplots, respectively. Also, five N rates and sources (0, nitroxin, 150 kg N ha-1, nitroxin + 150 kg N ha-1, and 300 kg N ha-1) were used in combination with two irrigation regimes [100% (normal) and 75% of plant water requirement (PWR)(Kc)]. The findings provided an indication that the canned yield and WUE could be raised by applying 300 kg N ha-1, 75% of PWR, and the CT system. The highest soil N content occurred in RT systems applied with nitroxin + 150 kg N ha-1 and 75% of PWR in the first year and under CT systems by applying nitroxin + 150 kg N ha-1 and the normal irrigation in the second year. Nevertheless, the maximum soil OC content occurred in the RT system applied with nitroxin + 150 kg N ha-1. To conclude, nitroxin-inoculated sweet corn responded favorably to the RT system with sufficient N rate and irrigation regimes down to 75% of PWR. Moreover, reducing irrigation water volume exerted no notable impact on reducing canned yield while it conserved water more significantly.

Harvest index (HI), ratio of seed yield to aboveground dry matter, is a very important parameter for estimating seed yield in several crop models. In this study, the importance, definition, variability and estimation methods of HI in crop models were discussed. HI estimation methods are categorized into two groups including: (i) complex methods that estimate HI from the beginning of seed growth to crop maturity, dynamically and (ii) simple methods that estimate the final HI at crop maturity. HI is a trait that is affected by many environmental parameters and the genotype of a crop. Soil water content or soil water suction during growing season, soil nutrient, groundwater depth, high air temperature, plant population and irrigation water salinity are some environmental factors affecting the HI. Therefore, in all models that used HI to estimate crop yield, either complex (e.g., AquaCrop model) or simple method, the harvest index estimating equations should be calibrated by changing the genotypes or cultivars, environmental and non-environmental parameters.