Craig E. Kallsen

Alfalfa yield as related to transpiration, growth stage and environment

SummaryThe utility of water production models as irrigation management tools is dependent upon their accuracy. Development of precise water production models requires a thorough understanding of how water and other factors interact to affect plant growth and yield. The objective of this experiment was to identify significant environmental variables which control water production function (transpiration vs. yield) variability between harvests and seasons for alfalfa (Medicago sativa L.) over a seven year (1981–1987) period in northwestern New Mexico. A single line-source design was used to supply a continuous gradient of irrigation (I) to the crop, and transpiration (T) was calculated as the difference between evapotranspiration, as estimated by the water balance method, and modeled soil water evaporation at each I level. Yield per cutting was found to be a function of T, growing degree-day accumulation, average daily solar radiation, year and harvest number within year. A multiple regression equation formulated with these variables explained 82% of the yield variability. Average yield per cut in 1981 at 50 mm of T was l Mg ha-1 and in 1985 at the same level of T was 2 Mg ha-1 based on the regression model. Yield per cut at any given level of T, as estimated by the coefficients of this equation reached a maximum at year 5.7 and a minimum in year 1. Within a season, yield per unit T was generally greatest at cut 1 and lowest at cut 2. Total seasonal yield was found to be a function of T and year which explained 90% of yield variability. Yield varied from 0.83 Mg ha-1 to 18.1 Mg ha-1 and T varied from 186 mm to 1298 mm.

Genetic analyses of phenological traits of pistachio (Pistacia vera L.)

Heritability of flowering and leafing date of pistachio (Pistacia vera L.) were estimated based on half-sib family and parent-offspring regression analyses. Narrow sense heritabilities of flowering date ranged from 0.68 to 0.88 based on half-sib analyses and from 0.89 to 0.95 based on parent-offspring regression analyses. The narrow sense heritability of leafing date was 0.75 based on half-sib analyses and 0.60 from parent-offspring regression analysis. First leafing date was highly correlated with flowering date (r =0.59–0.78), suggesting that first leafing date could be used to select for flowering date in seedlings long before the onset off lowering.

Irrigation effects on rooting patterns of Spring Barley

SummaryThe objective of this experiment was to quantitatively describe, on three dates throughout the growing season, the rooting patterns of spring barley (Hordeum vulgare L.) growing under an irrigation gradient on a clay loam soil (clayey over loamy, montmorillonitic (calcareous), thermic Vertic Torrifluvent) as Las Cruces, New Mexico. Evapotranspiration (Et) was calculated at 15 locations along the gradient, using the water balance method, and ranged from 320 to 565 mm in 1982 and 320 to 575 mm in 1983. Roots were first sampled before the irrigation treatments were started when the crop was in the tillering or jointing stage; secondly, in the middle of the growing season after heading, and finally at maturity. Soil was sampled in 0.15 m increments to a depth of 1.2 m at each location using a soil tube. Roots were extracted from the soil using a saline water flotation method. Total above-ground biomass was determined at maturity.

Comment on “Evolutionary transitions between beneficial and phytopathogenic Rhodococcus challenge disease management”

We would like to address a number of concerns regarding this paper (Savory et al., 2017)