Interactive effect of cobalt and nitrogen on growth, nodulation, yield and protein content of field grown pea

Pea (Pisum sativum L.) has increasing nutritional, commercial, and economical value, and initial low supply of N and Co is needed to increase nodulation, yield, and profit. A field experiment in 2010 was conducted at the University of Poonch Rawalakot located in the hilly region of the state of Azad Jammu and Kashmir, Pakistan. The aim of the study was to evaluate the effects of fertilization of N and Co on growth, nodulation, seed yield, seed composition of, and uptake of N and Co by pea plant. Treatments included three levels of N (0, 30, and 60 kg N center dot ha(-1) and represented as N-0, N-30, and N-60, respectively) combined with three levels of Co (0, 10, and 20 g Co center dot ha(-1) and represented as Co-0, Co-10, and Co-20, respectively), and the control represented as N0Co0. Results indicated that most of the morphological characteristics were increased with N-60. The greatest shoot length, root length, and chlorophyll content were recorded in the N60Co20. The number of root nodules increased from 6 in the control to 19 with fertilization of N and Co. Yield responses to N-Co fertilization occurred to all rates, and the highest yield, 2536 kg center dot ha(-1), was observed in the treatment N60Co10. Total N and Co uptake in the plant (shoot + root + seed) ranged between 16-147% and 3-331% over the control, while seed protein increased by 13-198% over the control by application of N and Co. This study demonstrates that N- and Co-deficient soils are likely to produce crops with low yields and seeds with low protein levels, and therefore, appropriate management of soil N and Co could be an effective approach to increase and sustain pea production in the small holding mountain ecosystems.