# Weed Detection in Rice Fields Using Remote Sensing Technique: A Review
## 4 Controlling Weed in Paddy Fields at Different Growth of Stages  
In general, rice growth periods can be identified in three stages. They are the vegetative stage, reproductive stage, and maturative or ripening stage [21]. Depending on agricultural and environmental conditions, the whole cycle takes about 120 to 125 days. The International Rice Research Institute (IRRI) splits the growth cycle into five stages [22]. A general idea of the growth cycle is presented in Figure 2, with morphology examples. Rice is generally a weak competitor with weeds. Therefore, the vegetative stage is critical in the paddy growth cycle. Successfully controlling weeds at this stage can deliver a 95% weed-free yield [23]. This is agreed with by [PERSON] et al. [24] because the effect of weeds in this stage will be at maximum. However, if we fail to prevent weeds from spreading in the vegetative stage, they will dominate the area, leading to a lack of sufficient space, light, and nutrients to grow and develop [25]. As a result, crops will experience uneven flowering and will not mature uniformly for the scheduled harvest [26; 27]. Figure 2: The growth cycle of a rice plant corresponds to the IRRI scale and sample structure. Once the tillering reaches its maximum number, the reproductive stage will occur, followed by the maturative or ripening stage. Excess water in the fields is drained, resulting in a drop in the overall biomass due to lower moisture content. The grain is maturing and becoming heavier. At this stage, the presence of weeds will not affect the development of the crop. Nevertheless, we cannot save the yield losses because weeds dominated the paddy plot and the number of paddy crops that survive the competition is nominal. In general, weed in paddy can be classified into three types. They are grasses, sedges and broadleaved weeds [28], and Table 1 shows a compilation of the primary weeds usually found in paddy fields. The environmental relationship between weed and rice is very complicated and complex [29]. The weed management system needs improvement to control the spreading of weeds. The traditional practices that include burning, hand sowing, manual spot spraying, herbicide pre-emergence or post-emergence application, and repetitive blade hoeing are not practical anymore. These practices impacted the non-target species and the ecosystem rather than benefiting production [30]. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Family Name** & **Scientific Name** & **Common Name** \\ \hline \begin{tabular}{c} Grasses weeds \\ Poaceae \\ \end{tabular}  & \begin{tabular}{c} _Oriza sativa complex_ \\ _Leptrohlca chinensis_ (L) [PERSON] \\ _Chloris harbata Suv._ \\ _Echinochla crus-galli_ (L.) \\ [PERSON]. \\ _Echinochla colana_ (L) [PERSON] \\ _Ischebaum rugosum [PERSON]_ \\ _Brachiaria muntica_ (Forsk.) [PERSON] \\ _Cynodon dactylion_ (L) Pers. \\ \end{tabular}  & \begin{tabular}{c} _Oriza sativa complex_ \\ _Leptrohlca chinensis_ (L) [PERSON] \\ _Sowollen fingersgrass_ \\ _Sowollen fingersgrass_ \\ _Barnyardgrass_ \\ _Jungle rice_ \\ _Ribbed muraniagrass_ \\ Para grass, buffalo grass_ \\ Bermuda grass_ \\ \end{tabular}  \\ \hline \begin{tabular}{c} Sedge weeds \\ Cyperaceae \\ \end{tabular}  & \ \begin{tabular}{c} _Fimbristyls miliacea_ (L.) [PERSON]. \\ _Cyperus tria_ \\ _Cyperus difformis_ \\ _Cyperus rotundus_ \\ _Eleocharis dulcis_ ([PERSON]) \\ _Henschel_ \\ _Fimbristyls globulos_ ([PERSON].) \\ _Kunth_ \\ _Fuirena umbellate [PERSON]_ \\ _Scripus grossus [PERSON]_ \\ _Scripus junzooides_ \\ _Scripus suspinus_ \\ \end{tabular}  &
\begin{tabular}{c} _Fimbristyls miliacea_ ([PERSON]) [PERSON]. \\ _Fimbristyls miliacea_ ([PERSON]) \\ _S_ril. \\ _S_ril. The traditional weed sampling for practice-oriented management is too costly, and this is not a recent concern. Since 2005, Brown and Noble [31] have developed automated methods for evaluating infestation.