MSc

Relative efficiency of rice varieties for absorption and utilization of soil and fertilizer phosphorus
An investigation was carried out at the college of Horticulture, Vellanikkara, Trichur, during the year 1984-’85 to study the efficiency of popular modern rice varieties of Kerala for absorption and utilization of soil and fertilizer P as well as for their capacity to P deficiency tolerance.
A series of pot culture experiments was conducted using five short duration (Rohini, Jyothi, Annapoorna, Triveni and IR-36) and eleven medium duration (Jaya, IR-8, Sabari, Bharathi, Mashuri, IR-20, M0-4, M0-6, M0-7, H-4 and IR-42) rice varieties in karappadam soil of Kuttanad region of Kerala.
The first pot culture trial involves evaluation of the above varieties for their capacity to utilize soil and applied fertilizer P using 32P labeled superphosphate. The experiment was carried out in CRD.
The relative performance of all the varieties as well as their root distribution pattern were compared from another pot culture trial under identical fertility conditions. Fertilizers and lime were applied as per the package of practices recommendations of the Kerala Agricultural University. The experiment was designed in CRD.
An attempt was also made to study the P requirement of each variety for the expression of maximum grain and straw yield from a solution culture trial. Solution containing all the macro and micronutrients was used for the experiment. The treatments consisted of combinations of different varieties and different levels of P supply. The various levels of P used were 0, 1, 2, 4, 5, and 10 ppm. The experiment was conducted in CRD factorial design.
The results indicated that cv, IR-36 was having a very low P requirement for the expression of maximum yield potential among short duration varieties and that it responded well to applied fertilizer P, indicating its fertilizer responsive nature as well as tolerance to P deficiency.
Triveni and Rohini were also having low requirements, but they differed in their dependence on the source of P to meet the requirement. Rohini was capable of utilizing native soil P efficiently while a good response to applied P was observed in the cv. Triveni.
Jyothi utilized both the sources of P viz. soil and fertilizer; efficiently but was found to have a higher requirement for giving maximum grain yield.
Among the medium duration varieties cv. Mashuri has the lowest requirement and majority of its requirement was met from the fertilizer revealing its P deficiency tolerance nature and responsiveness to applied fertilizer P.
Cv. IR-42 and Bharathi were found to be tolerant to P deficiency due to their capacity to utilize native soil P efficiently and low requirements of P.
Cv. H-4 was also having low requirement and it utilized both the sources efficiently. But this was not very much reflected on the grain yield.
Cv. IR-8 and Jaya had comparatively higher requirements and it reflected well on the grain yield. But these varieties yielded poor at lower levels indicating its susceptibility to P deficiency.