Yunnan Academy of Agricultural Sciences, Kunming, Yunnan 650205, China
We reported earlier that the sickle-shaped rices in South and West Asia which have been regarded generally as indica (Hsien) include many japonica (Keng) types (Yu et al. 1987). The representative varieties are Domsiah, Firooz, Sadri and Basmati. We found later that the both Hsien and Keng types of sickle-shaped rices differ ftom typical Hsien and Keng varieties to some extent, as they show low F1 fertilities when crossed with either of the typical varieties. Basmati 370 has also been reported to show semi-sterility in crosses with ordinary indica varieties (Engle et al. 1969). This fact is noteworthy in tracing the differentiation of the two subspecies of rice. Some of our investigations are presented in this note.
Compared with the sickle-shaped Hsien type, the Keng type is characterized by 1)better exsertion of panicles, 2) interval between first and second nodes of panicle axis being usually longer than 3 cm, 3) negative phenol interaction (Table 1), 4) glume hair being intermediate between typical Hsien and Keng types although more like the Keng type, 5) non-pubescent leaves, and 6) esterase zymograms similar to those of Keng varieties. Furthermore, their crosses with Hsien cultivars sometimes produced 1) black-hulled gram similar those found in Hsien X Keng crosses, 2) glume hair characteristic of the Keng type, or glabrous to nearly glabrous grains as found in glabrous land races which are Keng types, and 3) progeny plants with panicles and grain of the Keng type even though the sickle- shaped Keng rice has panicles and gram similar to those of ordinary Hsien varieties.
Table 1. Length of first internode of penicle axis and phenol reaction observed in Hsien and Keng types of sickle-shaped rice varieties
________________________________________________________________ 1st internode length (cm) Phenol reaction Type_____________________________ ______________________________ n Mean+/-SD Range n Nega- Slight Positive Mixed tive stain ________________________________________________________________ Keng 40 3.4+/-0.10 2.5-4.5 42 33 2 4 3 Hsien 23 2.2+/-0.15 1.4-3.1 23 8 6 6 3 ________________________________________________________________ n: No. of varieties observed.In view of these peculiarities of the sickle-shaped rices, especially their relatively low F1 fertilities with both Hsien and Keng varieties (Table 2), we are inclined to presume that they are a special type of "intermediate" between Hsien and Keng types and differ from other "intermediates" showing high F1 fertilities with both types. Two crosses between sickle-Hsien and sickle-Keng showed a somewhat high F1 fertility of 67.3% on the average. Other two crosses between sickle-Keng and sickle Aus also gave a mean fertility of 66.7%.
Table 2. F1 seed fertility from crosses between sickle-shaped Hsien and Keng and typical Hsien and Keng varieties
_______________________________________________________________________ Sickle- Crossed with F1 seed fertility (%) Total shaped ordinary ______________________________ no. of Mean+/-SD varieties varieties 100-80 80-60 60-40 40-20 20-0 crosses _______________________________________________________________________ Keng Keng 2 6 11 8 17 44 34.8+/-3.74 Hsien 1 17 11 7 14 50 42.1+/-3.67 Hsieh Keng 1 2 9 2 1 15 54.8+/-4.34 Hsien 4 9 2 5 20 60.1+/-4.75 Total 8 34 33 22 32 129 ______________________________________________________________________From these results, we raise questions. 1) Could the sickle-shaped rice be taken as a new type of "intermediates" in the differentiation of hsien and keng subspecies? 2) Do the stepwise decrease in mean F1 fertility from Hsien to Keng as shown in Table 2 and the higher F1 fertility found between sickle-Hsien and sickle-Keng suggest that the Keng type was derived from the Hsien type as proposed by Professor Ting? 3) Does our data justify the postulation that morphological changes have proceeded ahead of F1-sterility relationships?
References
Engle, L. M., T. T. Chang and D. A. Ramirez, 1969. The cytogenetics of sterility in F1 hybrids of indica X indica and indica X javanica varieties of rice (Oryza sativa L.). Philippine Agriculturist 53: 289-307.
Yu, W. J., X. K. Wang and K. S. Chung, 1987. Classification of the sickle-shaped rice cultivars into Hsien and Keng types. RGN 4: 68-70.