Seasonal effects of an iron content of iron-dense Philippine rices harvested in two locations

In Batac [Ilocos Norte, Philippines], all samples, except IR841-85 and PR27089-4-33-35-1, had higher grain iron than in Maligaya. This may be due to differences in soil properties (Gregorio et al. 1999) and irrigation water (Juliano 1993) in the two fields. The correlation coefficients, r sub 1=0.836 and r sub 2=0.825 indicate that the iron-dense traits among the samples are expressed in both locations. In Maligaya, lower iron concentrations during the WS [wet season] were observed, except PR31595-PSC101 and IR72860-80-3-3-3, which had 0.7 mg/kg increases, respectively. The lower solar radiation at the reproductive stage, which slowed down the movement of ions in the transpirational stream, may have caused the drop (Cabuslay et al. 2003). Of the 10 samples, only IR841-85 and PR 31595-PSC101 had poor mean milling potentials - poor brownrice yield, and unacceptable percent total milled and head rice like IR69745-251-2-2-1-1. Their moisture contents ranged from 10.8% to 11.6%. Low to intermediate - amylose varieties are preferred by most Filipinos (Juliano 1985) and all samples fall in these categories. Amylose content is the major eating quality factor in rice (Juliano 1993) and an indicator of volume expansion and water absorption during cooking, and correlates with hardness, whiteness, and dullness of cooked rice (Juliano 1985). Meanwhile, crude protein values ranged from 6.3% to 9.1%, with PR27423 - MS6 containing the lowest and PR31595 - PSC101 the highest. These values fall within the mean protein range (6.3-9.2%) of rice samples from different Asian countries (Juliano 1993). Generally, all samples had low to intermediate GT scores or alkali spreading values. PR27089-4-33-35-1 alone had high-intermediate GT score. Eight trained panelists described almost all cooked samples as white, glossy, cohesive, tender, smooth, and tasty. Most of the samples were also slightly aromatic, which means they have higher market value (Juliano, 1985). This also confirmed findings of Gregorio (2002) that higher grain iron concentrations were often observed in aromatic rices. However, IR68144-2B-2-2-3-2 had no aroma and was not acceptable to the consumer panel (72.2% in both seasons). The iron-denseness of the ten cultivars analyzed was quite stable across the two environments, although samples planted in Batac contained higher levels of iron in their known rice form than those in Maligaya during the 2002 WS. Iron concentrations tend to drop during the WS. Almost all of them had excellent physical properties, with intermediate-to-low amylose which are preferred by most Filipino consumers. Sensory evaluation showed that most of the samples were aromatic in cooked form, which supports findings of other studies that iron density correlates with aromatic properties of rice. Except IR68144-2B-2-2-3-2, the samples passed the acceptability test, thus further studies will verify its properties