Temperature-related Variables Associated with Yield of ‘Kerman’ Pistachio in the San Joaquin Valley of California

Abstract

<jats:p>Information on how annual pistachio yield is affected by air temperature (Ta) during the winter and growing season is lacking. Timely advance knowledge of the magnitude of the yield of the California pistachio harvest would be beneficial for the pistachio industry for efficient allocation of harvest and postharvest resources, such as personnel, harvesting machinery, trucks, processing facility capacity, crop storage facilities, and for making marketing decisions. The objective of this study was to identify parameters, especially Ta variables and time periods, calculated from Ta data during the previous fall, winter, spring, and summer, that were associated most closely with fall nut-crop yield. The premise of this study was that sequential, historical yield records could be regressed against a number of Ta-derived variables to identify Ta thresholds and accumulations that have value in explaining past and predicting subsequent nut yield. Of the 27 regression variables examined in this study, the following, which were all negatively correlated with subsequent yield, explained the greatest proportion of the variability present in predicting yield of ‘Kerman’ pistachio: yield of the previous-year harvest, hourly Ta accumulations above 26.7 or 29.4 °C from the time period between 20 Mar. and 25 Apr., hourly Ta accumulations below 7.2 °C from 15 Nov. to 15 Feb., and hourly Ta accumulations above 18.3 °C from 15 Nov. to 15 Feb.</jats:p>

UC pistachio cultivars show improved nut quality and are ready for harvest earlier than ‘Kerman’

“…Low and in pistachio in particular (Kallsen 2017;Zhang and Taylor 2011), because the underlying physiology is not well understood. Although difficult to quantify, it has been apparent that the adequacy of the winter rest periods for pistachio has ranged from low to high in the San Joaquin Valley, depending on orchard location and year.…”

‘Tejon’ Male Pistachio: An Early Blooming Pollenizer for ‘Gumdrop’

“…Beede et al (2006) reported a minimum requirement of 700 h < 7°C for 'Kerman' and 900 h for 'Peters' bloom. With reduced chilling, coincidence of male and female bloom is more important as reduced chill can shift male and female bloom periods in different directions and limit the period of bloom overlap (Kallsen, 2017). New cultivars with lower chilling requirements will be needed for continued pistachio production in California.…”

Identification of Key Periods of Temperature Influence on ‘Sirora’ Pistachio Nut Quality

“…For example, studies of apple (Malus domestica) have shown that autumn temperatures and sunlight hours can affect the yield the following season (Beattie and Folley, 1977;Jackson et al, 1983;Lakso 1987). Kallsen (2017) used multiple regression to explore the effects of air temperature on pistachio yields. He used more than 10 different periods with different air temperatures to correlate aspects of weather to yield.…”