Selection and realization of hybrid breeding progeny of Japonica rice in cold region based on pressure-state-response model

To improve the breeding of hybrid offspring, a stress-state-response (PSR) model was used to investigate the genetic, environmental, and selection factors affecting the progeny of japonica hybrid rice in cold regions. A conceptual model and evaluation system for the selection of progeny of japonica hybrid breeding in cold regions with 1 target, 3 criteria, and 18 indices was constructed, and the objective entropy weight and efficacy score were used to evaluate the comprehensive index. The results indicated that nine generations of hybrid offspring of 'Suijing 18' crossbreeding showed the highest weight of neck blast, followed by lodging level, and the lowest was seed setting rate. The indices of resistance to panicle blast, lodging level, and percentage of empty shell were the most important factors for selecting hybrid progenies in cold regions. In the PSR system evaluations, the order of influence was the response subsystem (0.6867) > the state subsystem (0.2651) > the pressure subsystem (0.0482). Meanwhile, the coefficient of variation of the index values ranged from 0 to 200.4%, which was beneficial for enhancing the breeding efficiency of progeny selection through a wide range of variation. The response, stress, and state subsystems were related. Dynamic changes in the environmental pressure conditions represented an important factor to promote changes in the response and state subsystems. The weight analysis of hybrid progeny showed that the order of influence of environmental pressure was neck blast > irrigation water temperature > planting density > fertilizer application. Compared with the current plant-type improvement theory and methods for hybrid offspring character selection, applying the PSR hybrid progeny selection theory and methods on rice breeding in cold regions effectively overcame the problems of multi-optimal trait aggregation, identification, and low selection efficiency due to the lack of breeding experience, qualitative and quantitative combinations, more emphasis on trait selection, and poor response decision making. Systematic, dynamic, and objective scientific planning, with accurate and efficient design, evaluation, and decision-making was realized by PSR, which was concise, practical, efficient, and operational. According to the ecological characteristics of rice farming in cold regions, the variety selection based on natural conditions in different regions differed. The state and response indices in the evaluation system should be adjusted when the theory and method presented here are used to select the hybrid offspring of rice. These principles and methods can also be used in soybean, corn, and other crops, all of which require further exploration. The results of this study provide a useful reference and technical basis for accelerating the breeding of new rice varieties with high quality, high yield, multi-resistance, and wide adaptability in cold regions.