Practicability of anther culture breeding in rice

Experiments have revealed that the age of the callus can affect callus differentiation. The differentiation ability decreases with increasing callus age and more albino plants occur. Different rice genotypes have different responses to 2,4 - dichlorophenoxy acetic acid (2,4-D), naphthalene acetic acid (NAA), and Kinetin (KT). Generally speaking, rice cultivars that are difficult to anther culture give better results by using a mixture of several hormones. The physiological status of donor plants can directly influence the culture results. If the meiotic divisions proceed under high temperature (above 35 deg C), more albino plants can be formed in the process of anther culture. Higher nitrogen content in the donor plant can increase the rate of green plantlet regeneration. The culture ability is controlled by the genotype. Regression analysis has shown that there is relatively higher overdominance for culture ability. Therefore, making the cross combinations among the parents with different culture abilities can overcome the culture difficulties. Identification and analysis of various generations of the same pollen plant (second through fifth generations) show that there is no degeneration of vigor among the generations. The offsprings of pollen plants are genetically stable. By multiple crosses and several anther culture, good characters from several parents can be accumulated together. With this method, the rice cultivar "Hua Han Zhao" was developed which confirmed that accumulating breeding by anther culture is a feasible breeding method. Stable and fully fertile pollen plants can be obtained from japonica/indica hybrids. So, anther culture of japonica/indica hybrids for breeding can be done on a large scale. Two rice cultivars, developed by anther culture breeding have been put into commercial use in large areas. "Xin Xu" was the first in 1976; "Hua Han Zhao" with the traits of early maturity, cold tolerance, and good quality was developed in 1981.