Mark E. Westgate

Low water potential disrupts carbohydrate metabolism in maize (Zea mays L.) ovaries

Water deficit during pollination increases the frequency of kernel abortion in maize (Zea mays L.). Much of the kernel loss is attributable to lack of current photosynthate, but a large number of kernels fail to develop on water-deficient plants even when assimilate supply is increased. We examined the possibility that assimilate utilization by developing ovaries might be impaired at low water potential ([Psi]w). Plants were grown in the greenhouse in 20-L pots containing 22 kg of amended soil. Water was withheld on the first day silks emerged, and plants were hand-pollinated 4 d later when leaf [Psi]w decreased to approximately - 1.8 MPa and silk [Psi]w was approximately -1.0 MPa. Plants were rehydrated 2 d after pollination. The brief water deficit inhibited ovary growth (dry matter accumulation) and decreased kernel number per ear by 60%, compared to controls. Inhibition of ovary growth was associated with a decrease in the level of reducing sugars, depletion of starch, a 75-fold increase in sucrose concentration (dry weight basis), and inhibition of acid invertase (EC 3.2.1.26) activity. These results indicate that water deficits during pollination disrupt carbohydrate metabolism in maize ovaries. They suggest that acid invertase activity is important for establishing and maintaining reproductive sink strength during pollination and early kernel development.

Announcement of New Division: C9—Biomedical, Health-Beneficial, and Nutritionally Enhanced Plants

Crop Science is pleased to announce that manuscript submissions are now being accepted to the journal through the new Provisional Division C9—Biomedical, Health-Benei cial, and Nutritionally Enhanced Plants. The focus of this Division is on plants as food or feed, and on the development and evaluation of novel characteristics and compositional quality traits in crops that are important to the health, well being, and nutritional requirements of humans. The editors at Crop Science look forward to providing CSSA members a venue for publishing research in this area, and to providing its readership with timely and informative reports in this interdisciplinary aspect of crop science. Although the editors anticipate receiving manuscripts with an overriding focus on crops for improved human nutrition or health, they expect and would welcome research coming from diverse disciplines. Possible areas of disciplinary focus could include: conventional breeding; transgenic modii cation; germplasm evaluation; or clinical, animal, or cell culture studies that evaluate crop products. Possible areas of health or nutrition focus might include: essential nutrients (e.g., vitamins, minerals, protein, lipids, and energy components); health-benei cial phytochemicals; anti-nutrients; bioactive compounds; or nutraceuticals. Possible targets of improvement for the harvested crop product could include: contribution of the food crop to meeting the Recommended Dietary Allowance (RDA) or Daily Reference Intake (DRI) of a given nutrient; improving anti-oxidant status; prevention of cancer; reducing disease risk; or as a possible therapy in disease treatment. With respect to the “feed” aspect of C09, this is not to be focused on feed quality as it pertains to growth and productivity of livestock. This would be more the purview of Division C06—Forage & Grazinglands or Division C03— Crop Ecology, Management & Quality. Rather, it would be anticipated to relate to the ef ect of feed quality (grains or forage) on the nutritional or health-benei cial composition of food products derived from livestock, which are subsequently destined for human consumption. Michael A. Grusak (USDA-ARS Children’s Nutrition Research Center, Baylor College of Medicine) has agreed to serve as the Technical Editor for C9 submissions. Koi Konan (Alabama A&M University), Hari Krishnan (University of Missouri), Janet Novotny (USDA-ARS Food Components and Health Laboratory), and Paul Scott (USDA-ARS and Iowa State University) have agreed to of er their time as Associate Editors. These individuals, with their diverse backgrounds and areas of expertise, look forward to handling all submissions in this new area of coverage in Crop Science. — Mark E. Westgate, Editor Michael A. Grusak, Technical Editor