## 4 Discussion  
A robust root system increases a plant's ability to absorb nutrients, boosting grain production [14]. Rice roots had an impact on the plant growth and grain yield, which was highly connected to root dispersion as well as to root morphology [21]. It has been reported that the uppermost layer (0-20 cm) of rice roots is crucial for moisture and nutrient absorption, which could improve the rate of grain filling, and, subsequently, the grain weight [37]. This study showed that total RN hill\({}^{-1}\), RV hill\({}^{-1}\), RL hill\({}^{-1}\), and RP varied significantly among the cultivars. The cultivar Binadhan-10 outperformed all the other cultivars in terms of root morphological features and yield, followed by Hira-2 and BRRI dhan29. Differences in root traits, growth parameters, and yield also occurred among the other cultivars. The genetic heterogeneity that exists among the cultivars may be the cause of the variations in root traits that have been reported. Genotypic differences in root traits have been documented in rice [38; 39; 40]. This study revealed that root traits were significantly correlated with yield,  
Figure 7: Mechanism involved in the selection of rice cultivars based on the relationship between root traits and yield. and might all perform a significant role in determining the selection of the best rice cultivar. Most studies demonstrate a strong association between rice root traits and the yield in the late growth stage [41; 42; 43]. An essential and effective agronomic indicator is the LAI, which measures crop growth and forecasts yield. LAI exerts a significant effect ton crop outputs [44]. In our study, the maximum LAI was recorded at 80 DAT, irrespective of the cultivar, and then it declined (data not shown). When spikelets started to grow, there was a drop in LAI dynamics. This was primarily because of leaf senescence; however, it is also likely that reserves were transferred to the expanding panicle. The former explanation emphasizes the significance of LAI and its connection to yields [45], which is corroborated by the positive association between LAI and yield. Researchers have noted a higher correlation between yield and LAI, indicating that yield rises as LAI grows [46; 47]. The amount of carbohydrates deposited in plants prior to heading, and those produced by photosynthesis following heading, are the key determinants of grain production, which is a result of dry-matter buildup [48]. TDM varied significantly among the cultivars during various growth phases in this study. The cultivar Binadhan-10 performed better in terms of TDM at 80 DAT, followed by the cultivars Hira-2 and BRRI dhan29. Total dry matter accumulation varied significantly, and ranged from 19.88 to 21.99 g plant\({}^{-1}\) depending on the genotype [49]. The cultivars Binadhan-10, Hira-2, and BRRI dhan29 may take up more nutrients from soil, which improves growth, increases LAI, and results in higher TDM. High-yielding cereals make the best photosynthetic progress during the vegetative growth stage and have an increased rate of dry matter production during the reproductive phase, which generally relies on an optimum LAI [50]. The tested cultivars varied significantly in relation to trends in growth attributes, namely CGR, RGR, and NAR. The sinus sheet plays a key role in photosynthesis and increases dry-matter content per unit area. In accordance with the findings of this study, cultivars with a larger LAI can be expected to have more CGR. In this study, the highest RGR was recorded in the early stages of plant growth, which linearly declined with time due to the loss of juvenility. At higher LAls, increased shading leads to a decline in NAR. The cause of the significant decrease in NAR was possibly accelerated by leaf production and premature closing of the canopy. This is because, in this state, the leaves absorb less solar radiation and the NAR is decreased. In recent years, the connection between root traits and grain yield has become a hot topic in rice research [21].