Nitrogen fertilization of warm‐season turfgrasses irrigated from varying irrigation systems: 2. Carbohydrate and protein content

A 3‐year study was conducted at New Mexico State University in Las Cruces, NM, to investigate whether different fertilization treatments affect the carbohydrate and protein content in two warm‐season grasses grown using water conservation strategies such as non‐potable saline irrigation water and a subsurface irrigation system. “Princess 77” bermudagrass (Cynodon dactylon L.) and “Sea Spray” seashore paspalum (Paspalum vaginatum O. Swartz) were irrigated with either potable (electrical conductivity [EC] = 0.6 dS m^?1) or saline (EC = 3.1 dS m^?1) water from either an overhead or a subsurface drip irrigation system. Four different fertilizers were used in this study: liquid slow release, granular slow release, granular urea and urea liquid, at two rates: 10 and 20 g N m^?2 yr^?1 for “Sea Spray” and 20 and 30 g N m^?2 yr^?1 for “Princess 77.” Carbohydrate (sucrose, starch, total soluble carbohydrates and total non‐structural carbohydrates) and protein content of the grasses were measured, and their effect on spring green‐up was determined. The total carbohydrate content within the stolons and rhizomes was found to be closely associated with speed of spring green‐up, resulting in R² values ranging from 0.36 to 0.76. The relationship between green‐up and carbohydrate content was similar for both grasses. Fertilizer treatment did not affect carbohydrate content in either grass under either irrigation system. Further analysis revealed that carbohydrate content in February was the best determinant for spring green‐up. Other sampling months also showed a significant correlation with spring green‐up, but with lower R² values.     

Germination Responses of Cañahua (Chenopodium pallidicaule Aellen) to Temperature and Sowing Depth: A Crop Growing Under Extreme Conditions

Cañahua (Chenopodium pallidicaule) is grown in the Altiplano of Bolivia and Peru, between 3810 and 4200 m a.s.l. Rural indigenous households have cultivated the cañahua as a subsistence crop for millennia. The seeds have a high content and quality of protein. We studied the relation between the following: (i) temperature and seed germination and (ii) the effect of temperature and sowing depth on seedling emergence of five cultivars and one landrace. Three experiments were conducted as follows: (i) seeds of a cultivar were germinated in Petri dishes at six temperatures (3, 5, 10, 14, 20 and 24 °C), (ii) sown at five depths (0, 5, 10, 25 and 50 mm) in a mixed peat soil substrate at three temperatures and (iii) one landrace (Lasta) and 5 cultivars (Lasta and Saihua growth habit) were sown in 6 depth (0, 5, 10, 25, 35 and 50 mm) in a sandy loam at two temperatures (5 and 15 °C). Temperature had significantly effect on the germination percentages of the plants (P < 0.001). Seeds germinated at the lowest temperature (3 °C). The estimated base temperature was close to 0 °C. A polynomial function described well the relation between time to 50% germination (t₅₀) and temperature in the interval from 3 to 24 °C resulting in a linear relationship between germination rate and temperature. Shallow sowing depth (5–25 mm) resulted in 80% germination at 15 °C. There were significant differences of emergence in relationship to burial depth (P < 0.001). Only few seedlings emerged when seeds were sown at 50 mm depth. We did not find significant differences in emergence of seedlings between Lasta and Saihua at 15 °C. Nevertheless, at 5 °C, seedlings of cañahua belonging to the Lasta growth habit form did have higher germination rate as were shown for the Kullaca cultivar and the Umacutama landrace. This may be attributed to larger seed size of these cultivars.     

The Sustainability of Quinoa Production in Southern Bolivia: from Misrepresentations to Questionable Solutions. Comments on Jacobsen (2011, J. Agron. Crop Sci. 197: 390–399)

Reviewing the situation of quinoa production in southern Bolivia, Jacobsen (2011, J. Agron. Crop Sci. 197: 390) argues that the booming export market has a negative effect on the environment and on the home consumption of quinoa, thereby leading to an environmental disaster in the region. In view of the scarcity of scientific knowledge on the rapid social and environmental dynamics in the region, we consider that Jacobsen’s review misrepresents the situation of quinoa production in southern Bolivia. Specifically, we argue that (i) the data presented by Jacobsen (2011, J. Agron. Crop Sci. 197: 390) do not support any drop in quinoa crop yield supposed to reflect soil degradation and (ii) his demonstration regarding home consumption of quinoa is ill‐founded from both a nutritional and a cultural point of view. We suggest that the diffusion of the arguments exposed by Jacobsen (2011, J. Agron. Crop Sci. 197: 390), because of their flaws, might have strong negative impacts on those concerned with sustainable food production and fair‐trade with developing countries. We conclude that, rather than reinforced agro‐technical controls on local farmers, the rising competition in the international quinoa market requires a shift towards an ethical economy and ethical research cooperation with quinoa producers.