Development of F1 Seeds and Comparative Evaluation of Seed-Set Performance in Normal and Reciprocal Crosses of BR11 × Kalijira Rice (Oryza sativa L.) Using Hot-Water Emasculation

Abstract

An experiment was conducted in the laboratory of the Department of Agriculture, Noakhali Science and Technology University (NSTU), from August to November 2024. The study aimed to develop F₁ seeds from crosses between the BR11 and Kalijira rice varieties using hot-water emasculation and to compare seed-set performance between the normal and reciprocal crosses. The experiment used a completely randomised design (CRD) with four replications, each represented by one emasculated panicle. Across both cross combinations, 579 spikelets were emasculated; 451 (77.89%) were fertilised and produced putative F₁ seeds, whereas 128 (22.11%) remained non-fertilised. The normal cross, BR11 (♀) × Kalijira (♂), had a mean seed-set percentage of 84.46 ± 2.85% (fertilisation success, 83.89%; sterility, 16.11%), whereas the reciprocal cross, Kalijira (♀) × BR11 (♂), had a mean of 68.98 ± 8.03% (fertilisation success, 70.00%; sterility, 30.00%). Although the effect size was large (Cohen's d = 1.28), the 15.48-percentage-point difference between the means was not statistically significant (F = 3.30 versus F₀.₀₅,₁,₆ = 5.99; LSD₀.₀₅ = 20.85%; independent t = 1.82, df = 6, p > 0.05). The number of emasculated spikelets was strongly and positively correlated with the number of putative F₁ seeds produced per panicle (r = 0.88, R² = 0.77), irrespective of cross direction. Both crossing directions produced seed; however, under the conditions of this experiment, the normal cross was more consistent and less variable (CV = 6.7% versus 23.3%).