Walley, F. L., Kyei-Boahen, S., Hnatowich, G. and Stevenson, C. 2005. Nitrogen and phosphorus fertility management for desi and kabuli chickpea. Can. J. Plant Sci. 85: 73-79. Chickpea (Cicer arietinum L.) is a relatively new crop in Saskatchewan and acreage has undergone a rapid expansion during the past decade. However, uncertainty remains regarding growth and yield responses of this grain legume to N and P fertilization under the semiarid environment of Saskatchewan. Field experiments were conducted at various locations in Saskatchewan to investigate chickpea response to starter N (0, 15, 30, and 45 kg N ha -1 ) and P (0, 20 and 40 kg P 2 O 5 ha -1 ) using desi cv. Myles and kabuli cv. Sanford. Starter N was side banded (2.5 cm to the side and 4 cm below the seed) and the P was placed in the seed row or side banded. Starter N promoted early vegetative growth of both desi and kabuli chickpea, but kabuli seed yield was unaffected by N application. Application of 30 or 45 kg N ha -1 enhanced desi yield by as much as 221 kg ha -1 . Starter N reduced N 2 fixation by kabuli chickpea whereas N 2 fixation by desi apparently was not as sensitive to inorganic N. Phosphorus (40 kg P 2 O 5 ha -1 ) enhanced chickpea vegetative growth, although only desi seed yield was significantly enhanced (121 kg ha -1 ). Shoot N and P accumulation in both chickpea types generally increased with P application, but N 2 fixation was unaffected. The results suggest that although N and P application had no effect on kabuli seed yield, desi yields may be optimized by the application of low rates of starter N (i.e., 30 kg N ha -1 ) and P (20 kg P 2 O 5 ha -1 ). L'engrais de démarrage azoté a été appliqué latéralement (bandes de 2,5 cm, à 4 cm sous la semence) alors que l'engrais P a été appliqué avec la semence ou sur le côté. L'engrais de démarrage azoté accélère la croissance des deux types de pois chiche en début de saison, mais le rendement grainier du cultivar kabuli n'est pas affecté par ce traitement. L'application de 30 ou de 45 kg de N par hectare accroît le rendement du pois chiche desi de jusqu'à 221 kg par hectare. L'engrais de démarrage azoté ralentit la fixation de N 2 par le pois chiche kabuli, mais la fixation de cet élément par le pois chiche desi n'est apparemment pas aussi sensible à l'azote minéral. Le phosphore (40 kg de P 2 O 5 par hectare) favorise la croissance végétative du pois chiche, quoique le rendement du pois desi soit le seul à connaître une hausse significative (121 kg par hectare). L'accumulation de N et de P dans les pousses des deux types de pois chiche est généralement plus élevée après l'application d'un engrais phosphaté, sans que la fixation de N 2 en soit touchée. Bien que les engrais N et P ne semblent pas modifier le rendement grainier du pois kabuli, les résultats indiquent qu'on pourrait optimiser celui du pois desi en appliquant une petite quantité d'engrais de démarrage azoté (à savoir, 30 kg de N par hectare) et d'engrais phosphaté (20 kg de P 2 O 5 par hectare).

A reduction in the atmospheric deposition of sulfur (S) and S-containing fertilizers has greatly reduced S inputs to the soil in recent years. At the same time, S removal from the soil has increased as a result of increased crop production and higher yields. Sulfur deficiency has been found to reduce yields in several crops. A study was conducted to gain an understanding of the S status of Nova Scotia soils that support carrot production, as well as to examine the effects of rate of S application, method of S application, and type of S fertilizer on carrot uptake, distribution, yield, and recovery. Initial S concentrations in carrot-producing fields ranged from 52–440 kg·ha-1 of S. In general, King's County soils were lower in S than Colchester County soils. In the S trial, banding and broadcasting S on the side of carrot rows improved yield, and recovery compared to placing the S in the seed row. Banding S also significantly increased undersize carrots, leaf fresh weight, leaf dry weight, and root fresh weight. Rate of S application did not affect yield, recovery, or growth of carrots. At this time, S supplies from the atmosphere and soil are sufficient to meet the demands of carrots produced for processing in Nova Scotia. Growers do not need to apply S as fertilizer at this time to improve carrot yields. Monitoring of the S status of soils should be periodically conducted to assess S concentration as SO2 emissions and crop production continue to change.

Genotypes and environmental parameters interactively act on plants and modify their yield responses through modifying photosynthetic processes. In order to optimize yield, it is critical to understand the photosynthetic behavior of the crop as altered by genotypes and environment. Leaf gas exchange parameters of carrot (Daucus carota L.) cultivars Cascade, Carson, Oranza, and Red Core Chantenay (RCC) were examined in response to various irradiances, fertility levels, moisture regimes, and to elevated CO2 concentrations. Leaf net photosynthetic rate (PN), stomatal conductance (gs), and transpiration rate (E) were measured. Cultivars responded similarly to increasing PAR and CO2 concentrations and did not differ in photosynthetic parameters. Increasing PAR from 100 to 1000 μmol·m-2·s-1 increased PN, which did not reach saturation. The gs and E increased to a peak between 600 and 800 μmol·m-2·s-1, then rapidly declined, resulting in a sharp increase in water use efficiency (WUE). Increasing CO2 concentrations from 50 to 1050 μmol·mol-1 increased PN until saturation at 650 μmol·mol-1. The gs and E increased to a peak at 350 μmol·mol-1 and then declined. WUE increased linearly with increasing CO2. Carrots exposed to drought over a period of 5 days decreased PN and E. The PN decrease was cultivar specific. Nutrient concentrations of 0 to 400 ppm gave a similar pattern of decrease for PN, E, and gs. Treatment of 50 ppm had the highest PN, E, and gs. The WUE generally increased with increasing nutrient concentration.

Planting soybean in April to avoid late‐summer drought is a common management practice in Mississippi. However, soybeans planted on Sharkey clay soils are often exposed to waterlogged conditions during the early spring. Experiments were conducted at the Delta Research and Extension Center (DREC) at Stoneville, MS, in 2003 and 2004 to assess the effects of induced flooding on soybean seedling emergence, stand establishment, and associated yield loss. In 2003, post‐planting flood treatments of 0 (control), 24, or 48 h were applied before seedling emergence or at the V1 stage. In 2004, similar treatments were applied except the timings of treatment were 0, 36, and 72 h. Results indicated that flooding prior to seedling emergence reduced number of plants and plant height, whereas only plant stand was affected when flooding was applied at the V1 stage. Number of pods per plant and number of seeds per pod were higher for the non‐flooded control compared with the 48‐h to 72‐h flood duration at the V1 stage, but the final seed yield was not affected in both years. The data suggest that waterlogged conditions lasting two to three days may not have significant effect on seed yield.