Estimate of chickpea production (Cicer arietinum L.) as a function of plant phenology

Abstract

Chickpea is a crop of the indeterminate type which can be an advantage to estimate in advance the production of this crop. The lack of water, cold or heat are the most limiting factors for the success of this culture; in the emergency phase, situations of waterlogging or extreme drought lead to an irregular installation of the culture, on the other hand, drought, excess water and extreme heat during the reproductive period, cause floral abortion and/or shorter cycles, and consequently, smaller income. Chickpea yield essentially depends on the number of seeds per unit area, which in turn depends on the length of the reproductive period. This is a problematic situation that proves the complexity of estimating the yield in leguminous crops in relation to species of determined habit. We try to know the dates of development of chickpeas, namely when the vegetative apex becomes reproductive (Beginning of Flowering, BF) and when the last flower of the apex no longer develops (End of Flowering, EF), this knowledge is fundamental anticipate and estimate the productive potential. Portugal is a country with a typical Mediterranean climate that has high capacity to produce grain legumes and the chickpea breeding program started at Plant Breeding Station, Elvas, Portugal in 1986. Since this data we have determined the dates of the BF and EF and, due to the difference between the two, the Reproductive Period (RP); the longer this period, the greater the number of pods and seeds per plant, and, as a consequence, greater final productions. In this way, over the course of 24 years, we have been recording the dates of entry into flowering and the end of flowering according to the thermal sum in Growing Degree Days (GDD) of by genotype, by trial and by year. In this analysis it was found that the BF is achieved when the sum of the GDD reaches 757 ºC, for maximum temperatures of 23 ºC, and the EF for sums of 1224 ºC and maximum temperatures of 30 ºC, that is, when temperatures above 28 ºC are registered, for two or three days in a row, is an indicator that the EF is approaching. It may happen later if precipitation occurs when the temperature reaches those values, but it varies from genotype to genotype. The new varieties, Elipse, Electra, Eleia, Eladir and Elfo confirm this situation, with the ELEIA variety standing out earlier in flowering.