## 4 Partition Aware-RPL Protocol Overview
### Parent Selection Algorithm
Moreover, when the farmland is hosting different crops distributed over different parcels, the proposed topology enables an efficient lossless data aggregation function like fusion and compression. This contrasts with standard RPL in terms of efficiency because of the high homogeneity of data within the parcel. Obviously, in one parcel it is common to have one kind of crop, presenting the same kind of parameters to continuously monitored, and requiring quite similar kind of decisions to be made. As shown in Figure 11, homogeneous data collected in a single parcel (P5) will be all gathered and processed at the Parcel Head (PH) then only the output message is forwarded up to the sink. ## 6 Case Study: Potato Pest Prevention

In the literature, applications using wireless smart sensor/actuator networks (WSN) in potato farms are quite widely proposed and applied. In fact, starting in 2005, the Lofar Agro [28] project aimed to apply sensor networks in protecting the potatoes plantation from a fungal disease known as the Phytophthora Infestants. In [29], an experimental WSN system for improving the cultivation of the potato crop is described. The proposed system makes important saving in terms of resources used in cultivation including fertilizers and irrigation water. In [30], PotatoSense, a precision agriculture application for monitoring a potato plantation field in Mauritius, is described. Different energy efficient algorithms are used in the proposed system to ensure that the system lifespan is prolonged. Recently, PotatoNet [31], that is an outdoor testbed for IP-enabled WSNs (LLNs), has been developed. It is designed to operate without on-site maintenance for extended periods of time. In this section, we are interested in the Potato Late Blight Pest. Thus, we consider realistic scenarios of a Potato Late Blight Pest Monitoring Application, where PA-RPL can be used to gather relevant data that help preventing favorable conditions for this disease to start. The late blight is considered to be the most devastating potato epidemic pests, and caused by _Pytophthora infestans_. Historically, this epidemic is known to be the main cause of the Irish famine in the 1840s [32]. In addition, and according to a recent study, 21% of the worldwide loss in cultivation of potatoes is attributed to the devastating late blight disease [33]. In this section, we start with describing such an application, and then, we move to evaluate the performance of our protocol in comparison with the standard RPL. ### Potato Late Blight Pest Prevention Application

The late blight is one of the most feared potato epidemic pests by farmers, as it can completely destroy the potato crop within few days if the weather is conducive for disease progress. It is caused by _Pytophthora infestans_ fungus-like oomycete. The _Pytophthora Infestans_, presented by Figure 12, has a complex structure similar to a microscopic plant. Its leaves, stem, and roots form its mycelium, through which, the pathogen reproduce. The mycelium grows on the stems, tubers, and leaves of the host plant, mainly a potato plant, or even on its residues. The fungus fruit,

Figure 11: PA-RPL DODAG: collection and aggregation of homogeneous data at parcel 5.

called sporangia (located in the sporangiophore as shown in Figure 12), can be carried by wind for up to 60 km of potato growing regions [33], leading to rapid spread on wide-scale of this pathogen. In addition, these sporangia contain each 8 zoospores, a sort of swimming seeds, allowing a rapid spread of the disease by rainwater. To better see how fast such a pathogen can spread, it is estimated that from a single lesion, may be produce up 300,000 new sporangia daily. Usually, the pathogen is dormant, waiting for the right weather conditions to wake up. In fact, only during specific weather conditions, a temperature around 13-15 \({}^{\circ}\)C and a relative humidity (R.H.) of 90-100%, that sporangia release their zoospores. Thus, controlling these conditions leads to controlling the spread of the disease.