Increase in ambient temperature beyond threshold level as predicted by global climate models may impact wheat production severely in India if it happens during grain filling stage. Grain filling rate (GFR) and grain filling duration (GFD) are critical determinant for final grain yield realization in wheat. GFR in wheat follow a slow-fast-slow pattern, however, wheat genotypes may have quantitative differences in this pattern. Ninty six diverse wheat
genotypes were evaluated for GFR in two phases i.e. during first 20 days after anthesis and thereafter up to physiological maturity and grain filling duration. Out of 96 genotypes, six namely, G958, G1203, G1219, G1275, HD2985 and HDCSW18 were having high GFR during initial phase while seven genotypes viz., G949, G1081, G1124, G1159, G1204, HD3059 and HD2380 exhibited high GFR at terminal phase of grain development. Genotypes, G1263, G1207, G1423 along with some of the released varieties, HD2285, WH1105 and HD2864 were having higher GFD. Correlation between the two traits were not significant (r = -0.17959). ANOVA for GFR and GFD indicated highly significant variability among the genotypes. QTLs identified for GFR and GFD elsewhere were validated in Indian breeding material under conservation agriculture. Two SSR markers viz., XCfd42 and Xwmc500 explained about 6% and 1% variation for GFR, respectively. Similarly, already reported marker Xwmc382 was able to explain about 8% of variation for GFD in the Indian breeding material. It has been postulated from the study that by crossing the genotypes with high GFR in different grain growth stages like HD CSW 18 and HD 3059, genotypes with consistently high grain filling rate throughout the grain growth stage can be developed. The markers XCfd42 and Xwmc 382 can be further explored for fine mapping to integrate in the breeding programme for selection.
Rhythmic Variations of the Growth Rate in Rice Embryo Revealed by Time Series Analysis
