Genetic control of grain length and shape in basmati lines of rice (Oryza sativa L.)

Understanding the genetics of grain length and grain shape is the prerequisite for developing premium quality Basmati varieties/lines. Two short grain with bold Japonica shape, one long grain slender Basmati shape and two extra long grain slender Basmati shape parental lines were used in the study. All the parents, F1's and F2 generations were raised during kharif 2008 at Rice Research Institute, Kala Shah Kaku, Pakistan. Grain length and shape was measured with a micrometer and were categorized following the Standard Evaluation System for Rice (IRRI, 1996). Chi square was used to compute the number of genes controlling the rice grain length and shape. All F1's of crosses involving extra long grain Basmati parents resulted in long grain and Basmati shape. No segregation for grain length and shape was observed in F2 of crosses involving extra long grain and long grain Basmati and non Basmati parents. F1 of long grain Basmati line 00521 showed short and bold shaped Japonica grains. The F2's of 99417/TN1 segregated into 63:1 for grain length, indicating 3 dominant genes responsible for extra long grain length in 99417. However, Pusa Basmati/TN1 segregated for grain length as 1023:1 indicating thereby 5 dominant genes for extra long grain length in Pusa Basmati. F2 generation of both the extra-long grain parents i.e., Pusa Basmati and 99417, showed no genetic segregation revealing that the genes responsible for grain length may be same in Pusa Basmati and 99417. The F2 of 00521 x King Dang Potang segregated into 1:67 for grain length indicating three recessive genes for Basmati grain length in 00521. A single dominant gene for Basmati grain shape in Pusa Basmati/TN1 and three recessive genes for Basmati shape in 00521 x King Dang Potang were observed.