Predicting Cotton Lint Yield Maps from Aerial Photographs

It is generally accepted that aerial images of growing crops provide spatial and temporal information about crop growth conditions and may even be indicative of crop yield. The focus of this study was to develop a straightforward technique for creating predictive cotton yield maps from aerial images. A total of ten fields in southern Georgia, USA, were studied during three growing seasons. Conventional (true color) aerial photographs of the fields were acquired during the growing season in two to four week intervals. The aerial photos were then digitized and analyzed using an unsupervised classification function of image analysis software. During harvest, conventional yield maps were created for each of the fields using a cotton picker mounted yield monitor. Classified images and yield maps were compared quantitatively and qualitatively. A pixel by pixel comparison of the classified images and yield maps showed that spatial agreement between the two gradually increased in the weeks after planting, maintained spatial agreement of between 40% and 60% during weeks eight to fourteen, and then gradually declined again. The highest spatial agreement between a classified image and a yield map was 78%. The highest average agreement was 52% and occurred 9.9 weeks after planting. The visual similarity between the classified images and the yield maps were striking. In all cases, the dates with the best visual agreement occurred between eight and ten weeks after planting, and generally, during July for southern Georgia. This method offers great potential for offering cotton farmers early-season maps that predict the spatial distribution of yield. Although these maps can not provide magnitudes, they clearly show the resulting yield patterns. With inherent knowledge of past performance, farmers can use this information to allocate resources, address crop growth problems, and, perhaps, improve the profitability of their farm operation. These maps are well suited to be offered to farmers as a service by a crop consultant or a cooperative.     

Root distribution patterns of peanut genotypes with different drought resistance levels under early‐season drought stress

Drought severely limits crop yield of peanut. Yet cultivars with enhanced root development enable the exploration of a greater volume of soil for water and nutrients, helping the plant survive. Root distribution patterns of three genotypes (ICGV 98305, ICGV 98324 and Tifton‐8) were compared when grown in well‐watered rhizoboxes and when grown in rhizoboxes where an early‐season drought was imposed using rain‐exclusion shelters. The treatments were arranged in a completely randomized design with three replications, and the experiment was conducted during two seasons at the Field Crop Research Station of Khon Kaen University, in Khon Kaen, Thailand. The root system of ICGV 98305, when grown under drought, had a significantly higher root length in the 30–110 cm deep soil layers and less roots in the 0–30 cm soil layers when under drought than when grown under well‐watered conditions. Roots of Tifton‐8 had the largest reductions in root length in upper soil layer and reduced in most soil layers. Tifton‐8 grown under drought was smaller than under well‐watered control for all root traits, showing negative response to drought. The peanut genotypes with high root traits in deeper soil layer under early‐season drought might contribute to drought avoidance mechanism.     

Seeing is Believing: The Role of Field Days and Tours in Precision Agriculture Education

The traditional role of field days and tours has been to introduce growers and agricultural professionals to new technologies and techniques so that the audience could see how these technologies or techniques could be practically used and applied. Based on this concept, the use of field days or tours to demonstrate the radically new technologies and site-specific management techniques behind precision farming is a perfect application of these tools. Indeed, a survey of precision farming field days held in a number of states found that field days were beneficial in showing growers and agricultural professionals global positioning systems, yield monitoring systems, techniques for grid soil sampling, software for geographic information systems, vehicle guidance systems, variable-rate application equipment, and a host of other technologies and processes. In particular, hands-on experiences, such as field demonstrations, guided sampling activities, and combine harvesting demonstrations are extremely well received and valuable. Indoor seminars featuring farmer panels, side-by-side software demonstrations, and demonstrations of geographic information systems have received high marks by participants. The survey found that a field day must be centered on a well-defined objective and a thorough understanding of the needs of the audience. Survey respondents unanimously agreed that precision farming field days and tours will be even more important as future advances in technology and management techniques are discovered. However, future precision agriculture field days or tours must be coupled with other issues or topics where precision agriculture technologies can be used to solve a practical problem and enhance management practices.     

Web-Based Educational Programs in Precision Agriculture

Establishing a set of electronic multimedia educational programs will expedite the understanding and implementation of key precision agriculture technologies. Several universities and private sector partners have joined together to accomplish this task and to make the material relevant to a diverse audience. Sections include base subject information, grower experiences, potential applications, guidance on how to determine the value of application techniques, and links to additional information. The learning modules (provided in a multimedia format) include information on Global Positioning Systems (GPS), Variable Rate Technologies (VRT), Remote Sensing (RS), sampling and scouting techniques, yield and quality monitoring, and Geographic Information Systems (GIS). The programs of the University of Georgia (UGA) and of Washington State University (WSU) are highlighted. A discussion of the fundamentals of electronic publishing is included. The design of a Internet-era educational program is crucial not only so that the material is conveyed in an efficient and effective way, but also so that ongoing maintenance is minimized.     

Varietal tolerance of zinc toxicity in peanuts

Peanuts (Arachishypogaea) are more susceptible to zinc (Zn) toxicity than other crops. However, there is potential for rapid evolution of Zn tolerance in many species. The objectives of this study were to test a nutrient solution screening procedure for identifying Zn tolerant cultivars and to identify plant characteristics and cultivars which have potential for Zn tolerance. Florunner was used as the test cultivar to determine the optimum Zn and pH levels for the nutrient solution cultivar screening test. The screening test showed that VA 81B and NC 6 (both virginia‐type peanuts) were more Zn sensitive than Florunner and that N. M. Valencia C and McRan (both valencia‐type peanuts) were more tolerant than Florunner. Field tests were carried out at three locations in Tift County, Georgia: Gibbs Farm (1986–87), Richards Farm (1991), and Stephens Farm (1992). Two out of four field tests did not have adequate soil Zn levels to test Zn tolerance; soil pH between 5.0 and 5.5 and Mehlich 1 soil Zn level ranging from 15–20 mg/kg should be adequate for cultivar screening in the field. Spanish‐type cultivars (Pronto, Spanco, and Starr) had the lowest toxicity ratings and highest yields (Gibbs, 1987), but yields were not economically viable for any cultivars. Aboveground plant Zn or calcium (Ca): Zn ratio were not good indicators of cultivar tolerance. However, low hull Zn concentration, high hull Ca: Zn ratio, and high plant Zn: root Zn ratio correlated well with high yield and low toxicity rating. Minimization of Zn uptake by the hulls would evidently be beneficial in aiding peanut plants in tolerating high soil Zn levels while producing economic yields.     

The variation of relative water content,SPAD chlorophyll meter reading,stomatal conductance,leaf area,and specific leaf area of Jerusalem artichoke genotypes under different durations of terminal drought in tropical region

This work assessed the responses of Jerusalem artichoke (JA) genotypes experienced to different durations of terminal drought for relative water content (RWC), SPAD chlorophyll meter reading (SCMR), stomatal conductance (SC), leaf area (LA) and specific leaf area (SLA), investigated the significant contributor of physiological traits to yield and yield reduction and diversity of physiological traits in terminal drought tolerance genotypes. Field research was conducted during the late-rainy season for 2 years using a split-plot design with four replications. The three irrigation treatments involved no-drought (SD0), short (SD1) and long (SD2) durations of terminal drought were arranged as main plots, and sub-plots were six genotypes of JA. The current study revealed that RWC, SC, LA, and SLA, were drastically reduced whilst SCMR values slightly increased under SD1 and SD2 compared to SD0. According to multiple linear regression indicated that SLA (SD0), and RWC (SD1 and SD2) had high contributions to tuber fresh weight (TFW), whereas SC had a high contribution to TFW reduction under terminal drought. Principal component analysis also confirmed that the diversity of LA, RWC, and SLA had maximized contributing traits, followed by HI, SCMR and SC in these breeding materials of JA under three irrigation treatments. Our finding emphasized that JA125 (low SLA), HEL256 and JA37 (high SLA) lead to the high performance of TFW under SD0, and they exhibited high TFW under SD1 by performing medium RWC. Likewise, JA4 and JA37 had high TFW under SD2 caused by medium RWC. HEL253 and JA60 were identified as terminal drought-tolerant genotypes because of performed medium SC, which contributed to a low reduction in TFW. Our promising results are the basis for further studies, SLA, RWC and SC are an important keys for screening drought tolerance (low economic yield reduction) and these genotypes studied could be used for parental lines to improved drought tolerance progenies through breeding programs under different durations of terminal drought-prone areas.