Two tetraploid (2n = 4x = 40) peanut (Arachis hypogaea L. subsp. hypogaea var. hypogaea) germplasm lines, GP‐NC WS 16 (SPT 06‐06) (Reg. No. GP‐235, PI 669445) and GP‐NC WS 17 (SPT 06‐07) (Reg. No. GP‐236, PI 669446), derived from interspecific hybridization, were developed in the peanut genetics program at North Carolina State University (NCSU), Raleigh, NC. These two lines were tested extensively by the North Carolina Agricultural Research Service from 2006 through 2012 in disease evaluation tests. They have unique alleles introgressed from the diploid (2n = 2x = 20) wild species, A. cardenasii Krapov. & W.C. Gregory. The germplasm lines are also unique in that they exhibited multiple disease resistances superior to the germplasm lines derived from A. cardenasii that were released previously by NCSU. Resistance to multiple diseases included early leaf spot (ELS), Cylindrocladium black rot (CBR), Sclerotinia blight (SB), and tomato spotted wilt (TSW). One of the lines, GP‐NC WS 17, also exhibited drought tolerance in field and greenhouse studies. Thus, it can be concluded that these two peanut germplasm lines derived from diploid wild species have multiple biotic stress resistances, specifically for ELS, CBR, SB, and TSWV, as well as abiotic stress resistance in the case of GP‐NC WS 17. These two lines should provide unique, improved germplasm for breeders interested in multiple disease resistance and in expanding the germplasm pool of A. hypogaea.

Drought is one of the most important environmental factors that limit crop production. Based on controlled-environment studies, it has been hypothesized that a limited-transpiration (TR lim ) trait under high vapor pressure de cit (VPD) is a mechanism for water conservation leading to yield increase under water-de cit conditions. e current research objective was to compare expression of TR lim in peanut (Arachis hypogaea L.) observed by whole-plant measurements in controlled environments and by leaf gas exchange measurements on plants grown in the eld. Six peanut genotypes with di erent breeding backgrounds, that is, wild-type, commercial cultivars, and advanced breeding lines were studied. Di erences were observed among genotypes in their expression of TR lim with increasing VPD in the controlled environment at 31/26°C. Within each breeding background, one genotype showed a linear increase in transpiration with increasing VPD while the other expressed the TR lim trait. In a second set of controlled environment experiments at 36/26°C, none of the six genotypes expressed the TR lim trait. In the eld, again none of the genotypes expressed the TR lim trait. e temperature to which the plants were exposed between the two controlled environments and eld trial appeared critical in the expression of the TR lim trait of three of the genotypes.

Theoretical derivation predicted growth retardation due to pot water limitations, i.e., pot binding. Experimental observations were consistent with these limitations. Combined, these results indicate a need for caution in high-throughput screening and phenotyping. Pot experiments are a mainstay in many plant studies, including the current emphasis on developing high-throughput, phenotyping systems. Pot studies can be vulnerable to decreased physiological activity of the plants particularly when pot volume is small, i.e., "pot binding". It is necessary to understand the conditions under which pot binding may exist to avoid the confounding influence of pot binding in interpreting experimental results. In this paper, a derivation is offered that gives well-defined conditions for the occurrence of pot binding based on restricted water availability. These results showed that not only are pot volume and plant size important variables, but the potting media is critical. Artificial potting mixtures used in many studies, including many high-throughput phenotyping systems, are particularly susceptible to the confounding influences of pot binding. Experimental studies for several crop species are presented that clearly show the existence of thresholds of plant leaf area at which various pot sizes and potting media result in the induction of pot binding even though there may be no immediate, visual plant symptoms. The derivation and experimental results showed that pot binding can readily occur in plant experiments if care is not given to have sufficiently large pots, suitable potting media, and maintenance of pot water status. Clear guidelines are provided for avoiding the confounding effects of water-limited pot binding in studying plant phenotype.

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First observation that chemical spray can induce limited-transpiration rate under high vapor pressure deficit. It appears that acibenzolar may be key in inducing this water conservation trait. Irrigation and water use have become major issues in management of turfgrasses. Plant health products that have been introduced into the turfgrass market have been observed to improve plant performance in water stress conditions. In this study, we evaluated whether a selection of common plant health products alter the ability of creeping bentgrass (Agrostis stolonifera L.) to control transpiration under high vapor pressure deficit (VPD). The plant health treatments--Daconil Action, Insignia, and Signature--were applied to plots on golf course putting greens located in Raleigh NC and in Scottsdale, AZ. Using intact cores removed from the putting greens, transpiration rates were measured over a range of VPDs in controlled conditions. In all cases stretching over a 3-year period, bentgrass cores from field plots treated with Daconil-Action limited transpiration under high VPD conditions, while check treatments with water, and others treated with Insignia or Signature did not. Transpiration control became engaged when VPDs reached values ranging from 1.39 to 2.50 kPa, and was not strongly influenced by the field temperature at which the bentgrass was growing. Because all plots in NC had been treated with chlorothalonil-the key ingredient in Daconil Action to control diseases-it was concluded that the likely chemical ingredient in Daconil Action triggering the transpiration control response was acibenzolar. This is the first evidence that the limited-transpiration trait can be induced by a chemical application, and it implies significant potential for ameliorating drought vulnerability in cool-season turfgrasses, and likely other plant species.