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Plant Nutrition-Physiology Research

Selected Highlights of the 2020 Plant Nutrition-Physiology Research

Dr. Peter Jeranyama

Irrigation water management. Irrigation scheduling continues to be a major challenge in cranberry production. Many growers tend to rely on the 1 inch per week “rule” from rain and irrigation despite evidence that in most years this results in some weeks with inadequate water and others with excess. It is highly likely that irrigation based on detecting available moisture in the soil and irrigating only when the moisture is inadequate to support plant growth results in better cranberry yield and less fruit rot. Values of soil water tension between -4.5 to -6 kPa seem to be adequate.  The results showed that the grower practice had tension readings of -2 kPa or less and consistently wetter than the tensiometer method. Fruit rot was 7% higher and yield was 24% lower under the grower practice relative to the tensiometer method.

Developing New Frost Prediction Models:  The cranberry industry has been well served through the diligent work of Dr. Franklin from the 1940s when he formulated predictive formulas for cranberry frost. The Franklin formulas cover the periods from April 20 to the end of June (spring frost) and from late August to the end of October (fall frost).  Recently, climate patterns and grower winter management practices have changed and in several of the last few years, there was a need for frost prediction as early as the last week of March.  Likewise, in the fall, late harvesting has become a more regular practice so that prediction for the first two weeks of November is also needed. Because Franklin formulas were developed for specific time periods, their use outside the period has yielded unreliable results. To try to mitigate against unreliable predictions outside the time period of Franklin, we are developing some formulas which have not been adopted by CCCGA for cranberry frost predictions. My program developed frost prediction formulas for April 1-14 (early spring) and November 1-15 (late fall). The fall formulas were used this fall to predict frost events.

Optimal Nitrogen Fertilizer Rates in Second-Generation Hybrid Cranberry Cultivars. Nitrogen is the most important element in cranberry production that impacts both vegetative growth and fruiting. Nitrogen fertilizer rates have been determined for native cultivars (“Early black” and “Howes”) and for the first-generation hybrids such as “Stevens”, but field data to support N fertilizer recommendations for the second-generation “super” cultivars such as “Mullica Queen”, “Crimson Queen” and “DeMoranville” are lacking. Because responses to N fertilizers are almost undetectable in the first year after application, but are clearly evident after the second and third years, it is critical to conduct fertilizer experiments over multiple years. In this study, we will refine N fertilizer recommendations for one native cultivar (‘Howes’), one first-generation hybrid cultivar (‘Stevens’), and all second-generation cultivars planted in Massachusetts (‘Crimson Queen’, ‘Mullica Queen’, and ‘DeMoranville’).

Cranberry Productivity Project. This is a collaborative project with Dr. Giverson Mupambi (UMass Cranberry), Dr. Casey Kennedy (ARS-USDA) and Dr. David Millar (ARS-USDA). We are monitoring 12 cranberry beds, half are low productivity and the other half are high productivity bogs. We are collecting fruit yield data, fruit rot, fruit quality, DNA analysis , delta 13C, 15N, soil Carbon, Soil P and soil N of at least 12 preselected coordinates. We are evaluating variables that are closely associated with crop productivity. This is part of  large project on food quality with ARS-USDA.


  1. Peter Jeranyama. Managing sun-scald on large fruited cultivars. September 2020 Newsletter. : pp. 3-4.
  2. Peter Jeranyama and Leela Uppala. April 24, 2020 Newsletter. Preliminary keeping quality.; pp. 1.
  3. Leela Uppala and Peter Jeranyama. June 26, 2020 Newsletter. Final keeping quality. pp 1.
  4. Peter Jeranyama, Anil Shrestha and Nilhari Neupane.2020. Sustainable food systems: diversity, scope and challenges, In: Leonard Rusinamhodzi (Ed.) The Role of Ecosystem Services in Sustainable Food Systems, Elsevier, London, UK, pp. 1-16.
  5. Peter Jeranyama. Monthly weather summaries (January -September, 2020)