Heat-Unit-Based Description of the Reproductive Development of Pea
- Bertrand Ney and
- Olivier Turc
Yield of pea (Pisum sativum L.) is strongly dependent on two yield components, seed number and individual seed mass, that depend on the sequential processes of reproductive development. In order to describe the reproductive development of pea, the progressions along the main stem of three stages of development—flowering, initiation of seed filling, and physiological maturity—were studied with three cultivars grown in different conditions. It was shown that the progressive development can be described by linear functions based on cumulative degree days (CDD), using the average between daily minimum and maximum temperatures and a base temperature of 0 °C. The rates of progression of flowering (RF) did not vary significantly in the most favorable growth conditions for individual plants, i.e., at low plant density. The rate of progression of the initiation of seed filling (RS) was not significantly different from that of RF. The time interval between the initiation of flowering and seed filling was also stable, for a given cultivar, but the time of physiological maturity varied widely and progressed faster than the other stages along the stem. At high plant densities, when competition between plants increased, RF and RS decreased, but as at low plant densities, both values were not significantly different. The time interval between initiation of flowering and seed filling remained stable. In order to assess the influence of plant density on development, RF was related the growth rate of the shoot during flowering (GR). The relationship showed that increased with GR until a threshold of GR. Above this threshold, which was similar for cultivars Solara and Frisson, RF remained constant. This asymptotic value, RFmax, differed between genotypes. If RFmax is known, a simple method is proposed to precisely estimate the periods of formation of yield components, seed number and individual seed mass, on a plant or even a node basis. Only three simple measurements—the time of initiation of flowering, time to maturity, and number of highest fruiting node at harvest—are required for this calculation.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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