No abstract

Fourteen winter-sown genotypes of Lupinus angustifolius L., comprising most of the Western Australian cultivars released since 1986, were studied over 2 years at 4 southern Chile locations. Pod wall proportion, pod wall specific weight, seed number per pod, mean seed weight, seed weight per pod, wall weight per pod, and mean pod weight were measured, separately sampling pods from the mainstem and pods from branches. The 2 pod positions differed significantly for all characteristics except wall weight per pod. Lower coefficients of variation and greater heritabilities for both pod wall proportion and pod wall specific weight were achieved with a sample of pods from branches than with a sample from the mainstem.The ranges for pod wall proportion and pod wall specific weight were small (31.8–35.8% and 27.0–34.7 mg/cm2, respectively); however, highly significant genotypic effects were found for both characters. Heritability estimates were moderate for pod wall proportion (0.27 and 0.44 for pods from mainstem and branches, respectively) and moderate to high for pod wall specific weight (0.56 and 0.61, respectively).Pod wall proportion and pod wall specific weight were significantly correlated, more so at the genetic level (rg�=�0.83 and rg = 0.76 for pods from mainstem and branches, respectively) than at the phenotypic level (rph = 0.57 and rph = 0.60, respectively). Pod wall specific weight was closely associated with wall weight per pod, meaning that larger pods call for thicker pod walls. Accordingly, selection for low pod wall specific weight in a breeding program could lead to light pods. Correlations with mean seed weight indicate that this trait could decrease as well.

Agreement that wheat (Triticum aestivum L.) is scarcely limited by source of assimilates during grain fill has not been confirmed when source was drastically decrease in high yield potential environments. Dry matter (DM) and water dynamics of growing grains being possibly able to explain grain weight (GW) responses to source-sink ratios (S-Sratios) in these conditions. Objectives were to evaluate response of GW to S-Sratios at different phases during grain fill, and relationship between DM and grain water content in response to different S-Sratios. Wheat was sown at field conditions during 2004-2005 and 2005-2006 growing seasons. Four S-Sratios were assessed: Control without S-Sratios modification (C), S-Sratios from anthesis (At) +12 d to physiological maturity (ShAll), S-Sratios from At +12 d to first half of grain fill (Sh1st) and from second half of grain fill to maturity (Sh2nd). Thousand grain weight (TGW), GW at individual positions (IGW), stabilized grain water content (SGWC) and grain filling rate (GFR) were measured. TGW sensitivity to S-Sratios varied according to length of treatment and its timing, i.e. ShAll, Sh1st, and Sh2nd treatments reduced TGW by 48%, 26%, and 22%, respectively. These reductions were little higher when IGW were evaluated in ShAll (i.e. 53%) and Sh1st (i.e. 33%) treatments and lower in Sh2nd (i.e. 12%). SGWC sensitivity was lower than that of IGW across S-Sratios (e.g. ShAll 27%, Sh1st 22%, and Sh2nd 5%). However, close association between IGW and SGWC (R 2 = 0.78, p ≤ 0.001) and between GFR and SGWC (R 2 = 0.98, p ≤ 0.001) was found regardless of S-Sratios and seasons.